{"id":3764,"date":"2025-04-23T16:41:37","date_gmt":"2025-04-23T07:41:37","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=3764"},"modified":"2025-04-23T16:41:39","modified_gmt":"2025-04-23T07:41:39","slug":"%e3%80%90%e5%ae%8c%e5%85%a8%e3%82%ac%e3%82%a4%e3%83%89%e3%80%91php-is_null%e9%96%a2%e6%95%b0%e3%81%ae%e4%bd%bf%e3%81%84%e6%96%b9%e3%81%a85%e3%81%a4%e3%81%ae%e3%83%99%e3%82%b9%e3%83%88%e3%83%97","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=3764","title":{"rendered":"\u3010\u5b8c\u5168\u30ac\u30a4\u30c9\u3011PHP is_null\u95a2\u6570\u306e\u4f7f\u3044\u65b9\u30685\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9 &#8211; isset\/empty\u3068\u306e\u9055\u3044\u3082\u89e3\u8aac"},"content":{"rendered":"\n<p>PHP\u958b\u767a\u306b\u304a\u3044\u3066\u3001\u5909\u6570\u304cnull\u304b\u3069\u3046\u304b\u3092\u6b63\u78ba\u306b\u5224\u5b9a\u3059\u308b\u3053\u3068\u306f\u3001\u5b89\u5b9a\u3057\u305f\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u69cb\u7bc9\u306e\u57fa\u672c\u3067\u3059\u3002\u3057\u304b\u3057\u3001PHP\u306b\u306f<code>is_null()<\/code>\u3001<code>isset()<\/code>\u3001<code>empty()<\/code>\u3001\u305d\u3057\u3066\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08<code>=== null<\/code>\uff09\u306a\u3069\u3001\u4f3c\u305f\u3088\u3046\u306a\u5224\u5b9a\u65b9\u6cd5\u304c\u8907\u6570\u5b58\u5728\u3059\u308b\u305f\u3081\u3001\u300c\u3069\u306e\u5834\u9762\u3067\u3069\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u3079\u304d\u304b\u300d\u3068\u3044\u3046\u7591\u554f\u3092\u6301\u3064\u958b\u767a\u8005\u3082\u591a\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<p>\u672c\u8a18\u4e8b\u3067\u306f\u3001<code>is_null()<\/code>\u95a2\u6570\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9\u304b\u3089\u3001\u95a2\u9023\u3059\u308b\u5224\u5b9a\u65b9\u6cd5\u3068\u306e\u9055\u3044\u3001\u30e2\u30c0\u30f3PHP\u3067\u306enull\u30c1\u30a7\u30c3\u30af\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u307e\u3067\u3001\u5b9f\u7528\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\u3068\u3068\u3082\u306b\u5fb9\u5e95\u89e3\u8aac\u3057\u307e\u3059\u3002PHP\u3067\u983b\u7e41\u306b\u906d\u9047\u3059\u308bnull\u5224\u5b9a\u306e\u554f\u984c\u3092\u89e3\u6c7a\u3057\u3001\u3088\u308a\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u305f\u3081\u306e\u77e5\u8b58\u304c\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u521d\u7d1a\u301c\u4e2d\u7d1a\u30ec\u30d9\u30eb\u306ePHP\u958b\u767a\u8005\u3092\u5bfe\u8c61\u306b\u3001\u4ee5\u4e0b\u306e\u5185\u5bb9\u306b\u3064\u3044\u3066\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>is_null\u95a2\u6570\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u69cb\u6587<\/li>\n\n\n\n<li>\u4ed6\u306enull\u5224\u5b9a\u65b9\u6cd5\u3068\u306e\u6bd4\u8f03\u3068\u4f7f\u3044\u5206\u3051<\/li>\n\n\n\n<li>\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30b7\u30fc\u30f3\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/li>\n\n\n\n<li>PHP 7\/8\u3067\u306e\u6700\u65b0\u306enull\u5224\u5b9a\u30c6\u30af\u30cb\u30c3\u30af<\/li>\n\n\n\n<li>\u3088\u304f\u3042\u308b\u30a8\u30e9\u30fc\u3068\u5bfe\u51e6\u6cd5<\/li>\n<\/ul>\n\n\n\n<p>\u305d\u308c\u3067\u306f\u3001PHP\u306enull\u5224\u5b9a\u3092\u30de\u30b9\u30bf\u30fc\u3057\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<div class=\"toc\"><br \/>\n<b>Warning<\/b>:  Undefined array key \"is_admin\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>116<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_category_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>121<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>128<\/b><br \/>\n    <div id=\"toc_container\" class=\"sgb-toc--bullets js-smooth-scroll\" data-dialog-title=\"\u76ee\u6b21\">\n      <p class=\"toc_title\">\u76ee\u6b21 <\/p>\n      <ul class=\"toc_list\">  <li class=\"first\">    <a href=\"#i-0\">PHP is_null\u95a2\u6570\u3068\u306f \u2013 \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u69cb\u6587<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">is_null\u95a2\u6570\u306e\u76ee\u7684\u3068\u57fa\u672c\u69cb\u6587<\/a>      <\/li>      <li>        <a href=\"#i-2\">\u623b\u308a\u5024\u306e\u4ed5\u7d44\u307f\u3068\u5177\u4f53\u7684\u306a\u52d5\u4f5c\u4f8b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-3\">NULL\u5024\u3068PHP\u306b\u304a\u3051\u308b\u610f\u5473<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-4\">is_null\u95a2\u6570\u3068NULL\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08=== null\uff09\u306e\u9055\u3044<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-5\">\u52d5\u4f5c\u306e\u9055\u3044\u3068\u30b3\u30fc\u30c9\u4f8b\u3067\u898b\u308b\u4f7f\u3044\u5206\u3051<\/a>      <\/li>      <li>        <a href=\"#i-6\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03\u3068\u30e2\u30c0\u30f3PHP\u3067\u306e\u6700\u9069\u89e3<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-7\">\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308b\u6319\u52d5\u306e\u9055\u3044<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-8\">is_null\u3001isset\u3001empty\u306e\u9055\u3044\u3092\u5fb9\u5e95\u6bd4\u8f03<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-9\">3\u3064\u306e\u95a2\u6570\u306e\u52d5\u4f5c\u539f\u7406\u3068\u8fd4\u308a\u5024<\/a>      <\/li>      <li>        <a href=\"#i-14\">\u5b9f\u7528\u30b7\u30fc\u30f3\u306b\u5fdc\u3058\u305f\u4f7f\u3044\u5206\u3051\u306e\u5224\u65ad\u57fa\u6e96<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-19\">\u6bd4\u8f03\u8868\u3067\u5206\u304b\u308b\u52d5\u4f5c\u306e\u9055\u3044<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-20\">is_null\u95a2\u6570\u306e\u6d3b\u7528\u30b7\u30fc\u30f3\u5225\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-21\">\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u5024\u306e\u691c\u8a3c\u3067\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/a>      <\/li>      <li>        <a href=\"#i-25\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u306b\u304a\u3051\u308b\u6d3b\u7528\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-30\">\u6761\u4ef6\u5206\u5c90\u3067\u306e\u52b9\u679c\u7684\u306a\u4f7f\u7528\u4f8b<\/a>      <\/li>      <li>        <a href=\"#i-37\">\u95a2\u6570\u306e\u5f15\u6570\u30c1\u30a7\u30c3\u30af\u3067\u306e\u5fdc\u7528<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-43\">\u914d\u5217\u8981\u7d20\u306enull\u30c1\u30a7\u30c3\u30af\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-49\">PHP 7\/8\u6642\u4ee3\u306eNULL\u5224\u5b9a\u3068\u6700\u65b0\u30c6\u30af\u30cb\u30c3\u30af<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-50\">Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u4f7f\u3063\u305f\u7c21\u6f54\u306a\u8a18\u8ff0\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-57\">Nullsafe\u6f14\u7b97\u5b50\u3067\u306enull\u30c1\u30a7\u30c3\u30af\u52b9\u7387\u5316<\/a>      <\/li>      <li>        <a href=\"#i-66\">Null\u578b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3078\u306e\u9032\u5316\u3068\u30e2\u30c0\u30f3\u624b\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-72\">\u540d\u524d\u7a7a\u9593\u3067\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u547c\u3073\u51fa\u3057\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-78\">is_null\u95a2\u6570\u4f7f\u7528\u6642\u306e\u3088\u304f\u3042\u308b\u30a8\u30e9\u30fc\u3068\u5bfe\u51e6\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-79\">\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u3088\u308b\u8b66\u544a\u30e1\u30c3\u30bb\u30fc\u30b8\u306e\u56de\u907f\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-88\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306enull\u30c1\u30a7\u30c3\u30af\u6642\u306e\u6ce8\u610f\u70b9<\/a>      <\/li>      <li>        <a href=\"#i-98\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3068\u306a\u308b\u5834\u9762\u3068\u5bfe\u7b56<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-108\">\u914d\u5217\u64cd\u4f5c\u6642\u306e\u843d\u3068\u3057\u7a74\u3068\u56de\u907f\u7b56<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-116\">\u307e\u3068\u3081\uff1a\u72b6\u6cc1\u306b\u5fdc\u3058\u305fis_null\u95a2\u6570\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-117\">\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\u30c1\u30fc\u30c8\u30b7\u30fc\u30c8<\/a>      <\/li>      <li>        <a href=\"#i-124\">is_null\u95a2\u6570\u3092\u4f7f\u3063\u305f\u5805\u7262\u306a\u30b3\u30fc\u30c9\u4f5c\u6210\u306e\u30dd\u30a4\u30f3\u30c8<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-133\">\u30af\u30ea\u30fc\u30f3\u30b3\u30fc\u30c9\u306b\u5411\u3051\u305f\u6b21\u306e\u30b9\u30c6\u30c3\u30d7<\/a>      <\/li>    <\/ul>  <\/li><\/ul>\n      <a href=\"#\" class=\"sgb-toc-button js-toc-button\" rel=\"nofollow\" data-open-dialog=\"true\"><i class=\"fa fa-list\"><\/i><span class=\"sgb-toc-button__text\">\u76ee\u6b21\u3078<\/span><\/a>\n    <\/div><\/div><h2 class=\"wp-block-heading\" id=\"i-0\">PHP is_null\u95a2\u6570\u3068\u306f \u2013 \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u69cb\u6587<\/h2>\n\n\n\n<p>PHP\u306b\u304a\u3051\u308b<code>is_null()<\/code>\u95a2\u6570\u306f\u3001\u5909\u6570\u304cNULL\u5024\u304b\u3069\u3046\u304b\u3092\u53b3\u5bc6\u306b\u5224\u5b9a\u3059\u308b\u305f\u3081\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3067\u3059\u3002\u30b7\u30f3\u30d7\u30eb\u306a\u304c\u3089\u5f37\u529b\u306a\u3053\u306e\u95a2\u6570\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306a\u30b3\u30fc\u30c9\u4f5c\u6210\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002\u307e\u305a\u306f\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u69cb\u6587\u304b\u3089\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-1\">is_null\u95a2\u6570\u306e\u76ee\u7684\u3068\u57fa\u672c\u69cb\u6587<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306f\u3001\u5909\u6570\u304cNULL\u5024\u304b\u3069\u3046\u304b\u3092\u53b3\u5bc6\u306b\u5224\u5b9a\u3059\u308b\u305f\u3081\u306ePHP\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3067\u3059\u3002PHP 4.0.4\u304b\u3089\u5c0e\u5165\u3055\u308c\u305f\u3053\u306e\u95a2\u6570\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u57fa\u672c\u69cb\u6587\u3067\u4f7f\u7528\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">bool is_null(mixed $var)\n<\/pre>\n\n\n\n<p>\u3053\u306e\u95a2\u6570\u306f\u3001\u5f15\u6570\u3068\u3057\u3066\u6e21\u3055\u308c\u305f\u5909\u6570\u304c\u53b3\u5bc6\u306bNULL\u5024\u3067\u3042\u308b\u5834\u5408\u306b\u306e\u307f<code>true<\/code>\u3092\u8fd4\u3057\u3001\u305d\u308c\u4ee5\u5916\u306e\u5834\u5408\u306f<code>false<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u57fa\u672c\u7684\u306a\u4f7f\u7528\u4f8b\u306f\u6b21\u306e\u3068\u304a\u308a\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$var1 = null;  \/\/ \u660e\u793a\u7684\u306bnull\u3092\u4ee3\u5165\n$var2 = 0;     \/\/ \u6570\u5024\u306e0\n$var3 = \"\";    \/\/ \u7a7a\u6587\u5b57\u5217\n$var4 = false; \/\/ \u8ad6\u7406\u5024\u306efalse\n\n\/\/ NULL\u5024\u306e\u5834\u5408\u306e\u307ftrue\u3092\u8fd4\u3059\nvar_dump(is_null($var1)); \/\/ bool(true)\nvar_dump(is_null($var2)); \/\/ bool(false)\nvar_dump(is_null($var3)); \/\/ bool(false)\nvar_dump(is_null($var4)); \/\/ bool(false)\n<\/pre>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306e\u4e3b\u306a\u76ee\u7684\u306f\u3001\u4ed6\u306e\u300c\u507d\u300d\u3068\u8a55\u4fa1\u3055\u308c\u308b\u5024\uff080\u3001\u7a7a\u6587\u5b57\u5217\u3001false\uff09\u3068NULL\u5024\u3092\u660e\u78ba\u306b\u533a\u5225\u3059\u308b\u3053\u3068\u3067\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u5909\u6570\u306e\u72b6\u614b\u3092\u3088\u308a\u6b63\u78ba\u306b\u5224\u65ad\u3057\u3001\u9069\u5207\u306a\u51e6\u7406\u3092\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-2\">\u623b\u308a\u5024\u306e\u4ed5\u7d44\u307f\u3068\u5177\u4f53\u7684\u306a\u52d5\u4f5c\u4f8b<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u30b7\u30f3\u30d7\u30eb\u306a\u623b\u308a\u5024\u306e\u4ed5\u7d44\u307f\u3092\u6301\u3063\u3066\u3044\u307e\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5f15\u6570\u304c<strong>NULL\u5024<\/strong>\u3067\u3042\u308b\u5834\u5408\u306f <code>true<\/code> \u3092\u8fd4\u3059<\/li>\n\n\n\n<li>\u5f15\u6570\u304c<strong>NULL\u4ee5\u5916\u306e\u5024<\/strong>\u3067\u3042\u308b\u5834\u5408\u306f <code>false<\/code> \u3092\u8fd4\u3059<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u306e\u6319\u52d5\u3092\u69d8\u3005\u306a\u30b1\u30fc\u30b9\u3067\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u660e\u793a\u7684\u306anull\u5024\n$var = null;\nvar_dump(is_null($var)); \/\/ bool(true)\n\n\/\/ \u5024\u3092\u4ee3\u5165\u3057\u305f\u5909\u6570\n$var = '\u3053\u3093\u306b\u3061\u306f';\nvar_dump(is_null($var)); \/\/ bool(false)\n\n\/\/ \u6570\u5024\u3084\u8ad6\u7406\u5024\u306e\u5834\u5408\nvar_dump(is_null(0));      \/\/ bool(false)\nvar_dump(is_null(''));     \/\/ bool(false)\nvar_dump(is_null(false));  \/\/ bool(false)\nvar_dump(is_null([]));     \/\/ bool(false)\n\n\/\/ \u95a2\u6570\u306e\u623b\u308a\u5024\u3092\u76f4\u63a5\u30c1\u30a7\u30c3\u30af\nfunction returnNull() {\n    return null;\n}\nvar_dump(is_null(returnNull())); \/\/ bool(true)\n\n\/\/ \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u7d50\u679c\u306a\u3069\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u5b9f\u8df5\u7684\u306a\u4f8b\n$result = getUserData($userId); \/\/ \u4eee\u306b\u3053\u308c\u304c\u30e6\u30fc\u30b6\u30fc\u30c7\u30fc\u30bf\u53d6\u5f97\u95a2\u6570\nif (is_null($result)) {\n    \/\/ \u30e6\u30fc\u30b6\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\n    echo \"\u30e6\u30fc\u30b6\u30fc\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\";\n} else {\n    \/\/ \u30e6\u30fc\u30b6\u30fc\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306e\u51e6\u7406\n    echo \"\u30e6\u30fc\u30b6\u30fc\u540d: \" . $result['name'];\n}\n<\/pre>\n\n\n\n<p><code>is_null()<\/code>\u306f\u4e09\u9805\u6f14\u7b97\u5b50\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u8a2d\u5b9a\u306b\u3082\u4f7f\u7528\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ null\u306e\u5834\u5408\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3059\u308b\n$username = is_null($user-&gt;name) ? '\u30b2\u30b9\u30c8' : $user-&gt;name;\n<\/pre>\n\n\n\n<p>\u6ce8\u610f\u70b9\u3068\u3057\u3066\u3001\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u306a\u3044\u5909\u6570\u306b\u5bfe\u3057\u3066<code>is_null()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u8b66\u544a\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u767a\u751f\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308b\u4f7f\u7528\nvar_dump(is_null($undefined_var)); \/\/ Warning: Undefined variable\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-3\">NULL\u5024\u3068PHP\u306b\u304a\u3051\u308b\u610f\u5473<\/h3>\n\n\n\n<p>PHP\u306b\u304a\u3044\u3066\u3001<code>NULL<\/code>\u306f\u300c\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u300d\u307e\u305f\u306f\u300c\u5024\u304c\u672a\u5b9a\u7fa9\u3067\u3042\u308b\u300d\u3053\u3068\u3092\u8868\u3059\u7279\u5225\u306a\u5024\u3067\u3059\u3002\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u306f\u533a\u5225\u3055\u308c\u306a\u3044\u305f\u3081\u3001<code>null<\/code>\u3001<code>NULL<\/code>\u3001<code>Null<\/code>\u306e\u3044\u305a\u308c\u3082\u540c\u3058\u610f\u5473\u3067\u4f7f\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<p>NULL\u5024\u304c\u767a\u751f\u3059\u308b\u4e3b\u306a\u72b6\u6cc1\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5909\u6570\u306b\u660e\u793a\u7684\u306b<code>null<\/code>\u304c\u4ee3\u5165\u3055\u308c\u305f\u5834\u5408<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$var = null;\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>unset()<\/code>\u95a2\u6570\u3067\u5909\u6570\u304c\u7834\u68c4\u3055\u308c\u305f\u5f8c<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$var = '\u3053\u3093\u306b\u3061\u306f';\nunset($var);\n\/\/ \u3053\u306e\u6642\u70b9\u3067$var\u306fnull\u3068\u540c\u69d8\u306e\u72b6\u614b\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b58\u5728\u3057\u306a\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3084\u30e1\u30bd\u30c3\u30c9\u306b\u30a2\u30af\u30bb\u30b9\u3057\u305f\u5834\u5408<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$obj = new stdClass();\n$value = $obj-&gt;nonExistentProperty; \/\/ null\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u623b\u308a\u5024\u3092\u8fd4\u3055\u306a\u3044\u95a2\u6570\u304b\u3089\u306e\u623b\u308a\u5024<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">function noReturn() {\n    \/\/ return\u6587\u304c\u306a\u3044\n}\n$result = noReturn(); \/\/ null\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306eNULL\u5024\u3092\u53d6\u5f97\u3057\u305f\u5834\u5408<\/li>\n<\/ul>\n\n\n\n<p>NULL\u5024\u306f\u4ed6\u306e\u300c\u507d\u300d\u3068\u8a55\u4fa1\u3055\u308c\u308b\u5024\uff08<code>false<\/code>\u3001<code>0<\/code>\u3001\u7a7a\u6587\u5b57\u5217\u3001\u7a7a\u914d\u5217\uff09\u3068\u306f\u660e\u78ba\u306b\u533a\u5225\u3055\u308c\u307e\u3059\u3002\u3053\u308c\u306fPHP\u306e\u578b\u30b7\u30b9\u30c6\u30e0\u306b\u304a\u3044\u3066\u91cd\u8981\u306a\u610f\u5473\u3092\u6301\u3061\u3001\u7279\u306bPHP 7\u4ee5\u964d\u3067\u306f\u578b\u5ba3\u8a00\u3068\u7d44\u307f\u5408\u308f\u305b\u3066<code>?int<\/code>\u306e\u3088\u3046\u306aNull\u8a31\u5bb9\u578b\u3068\u3057\u3066\u6271\u308f\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-4\">is_null\u95a2\u6570\u3068NULL\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08=== null\uff09\u306e\u9055\u3044<\/h2>\n\n\n\n<p>PHP\u3067null\u5024\u3092\u5224\u5b9a\u3059\u308b\u65b9\u6cd5\u306f\u8907\u6570\u3042\u308a\u307e\u3059\u304c\u3001\u6700\u3082\u4e00\u822c\u7684\u306a\u306e\u306f<code>is_null()<\/code>\u95a2\u6570\u3068<code>=== null<\/code>\u306b\u3088\u308b\u6bd4\u8f03\u3067\u3059\u3002\u4e00\u898b\u4f3c\u3066\u3044\u308b\u3088\u3046\u306b\u898b\u3048\u308b\u3053\u308c\u3089\u306e\u65b9\u6cd5\u3067\u3059\u304c\u3001\u4f7f\u7528\u72b6\u6cc1\u306b\u3088\u3063\u3066\u52d5\u4f5c\u3084\u9069\u5207\u306a\u9078\u629e\u80a2\u304c\u7570\u306a\u308a\u307e\u3059\u3002\u4e21\u8005\u306e\u9055\u3044\u3092\u6df1\u304f\u7406\u89e3\u3057\u3066\u3001\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u5411\u4e0a\u306b\u6d3b\u304b\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-5\">\u52d5\u4f5c\u306e\u9055\u3044\u3068\u30b3\u30fc\u30c9\u4f8b\u3067\u898b\u308b\u4f7f\u3044\u5206\u3051<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u3068<code>=== null<\/code>\u306b\u3088\u308b\u6bd4\u8f03\u306f\u3001\u540c\u3058\u76ee\u7684\u3092\u679c\u305f\u3057\u307e\u3059\u304c\u3001\u52d5\u4f5c\u539f\u7406\u304c\u7570\u306a\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>is_null()<\/code>\uff1a\u95a2\u6570\u547c\u3073\u51fa\u3057\u306b\u3088\u308b\u5224\u5b9a<\/li>\n\n\n\n<li><code>=== null<\/code>\uff1a\u53b3\u5bc6\u6bd4\u8f03\u6f14\u7b97\u5b50\u306b\u3088\u308b\u76f4\u63a5\u6bd4\u8f03<\/li>\n<\/ul>\n\n\n\n<p>\u57fa\u672c\u7684\u306a\u52d5\u4f5c\u3092\u6bd4\u8f03\u3057\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u660e\u793a\u7684\u306bnull\u3092\u4ee3\u5165\u3057\u305f\u5909\u6570\u306e\u5834\u5408\n$var = null;\nvar_dump(is_null($var));  \/\/ bool(true)\nvar_dump($var === null);  \/\/ bool(true)\n\n\/\/ \u5024\u3092\u6301\u3064\u5909\u6570\u306e\u5834\u5408\n$var = 0;\nvar_dump(is_null($var));  \/\/ bool(false)\nvar_dump($var === null);  \/\/ bool(false)\n\n\/\/ \u5225\u306e\u4f8b\n$var = '';\nvar_dump(is_null($var));  \/\/ bool(false)\nvar_dump($var === null);  \/\/ bool(false)\n<\/pre>\n\n\n\n<p>\u4e0a\u8a18\u306e\u4f8b\u3067\u306f\u3001\u4e21\u8005\u306e\u52d5\u4f5c\u306f\u540c\u3058\u7d50\u679c\u3092\u793a\u3057\u3066\u3044\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u5b9f\u969b\u306e\u4f7f\u7528\u72b6\u6cc1\u306b\u3088\u3063\u3066\u9069\u5207\u306a\u9078\u629e\u80a2\u306f\u5909\u308f\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u5834\u5408\n$user = new User();\n\n\/\/ \u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3057\u306a\u3044\u53ef\u80fd\u6027\u304c\u3042\u308b\u5834\u5408\nif (is_null($user-&gt;name)) {\n    \/\/ \u51e6\u7406\n}\n\n\/\/ \u307e\u305f\u306f\nif ($user-&gt;name === null) {\n    \/\/ \u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>\u4e00\u822c\u7684\u306b\u306f\u3001\u30b3\u30fc\u30c9\u306e\u4e00\u8cab\u6027\u3084\u53ef\u8aad\u6027\u3092\u512a\u5148\u3057\u3066\u4f7f\u3044\u65b9\u3092\u9078\u629e\u3059\u308b\u306e\u304c\u826f\u3044\u3067\u3057\u3087\u3046\u3002\u591a\u304f\u306e\u30e2\u30c0\u30f3PHP\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306f\u3001<code>=== null<\/code>\u306e\u65b9\u304c\u95a2\u6570\u547c\u3073\u51fa\u3057\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u306a\u304f\u7c21\u6f54\u3067\u3042\u308b\u305f\u3081\u63a1\u7528\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-6\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03\u3068\u30e2\u30c0\u30f3PHP\u3067\u306e\u6700\u9069\u89e3<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u3068<code>=== null<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5dee\u306f\u6c17\u306b\u306a\u308b\u3068\u3053\u308d\u3067\u3059\u3002\u7c21\u5358\u306a\u30d9\u30f3\u30c1\u30de\u30fc\u30af\u3067\u6bd4\u8f03\u3057\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ 100\u4e07\u56de\u306e\u30eb\u30fc\u30d7\u3067\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03\n$var = null;\n$startTime = microtime(true);\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    is_null($var);\n}\n$endTime = microtime(true);\necho \"is_null(): \" . ($endTime - $startTime) . \" \u79d2\\n\";\n\n$startTime = microtime(true);\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $var === null;\n}\n$endTime = microtime(true);\necho \"=== null: \" . ($endTime - $startTime) . \" \u79d2\\n\";\n\n\/\/ \u5b9f\u884c\u7d50\u679c\u4f8b\uff1a\n\/\/ is_null(): 0.12 \u79d2\n\/\/ === null: 0.08 \u79d2\n<\/pre>\n\n\n\n<p>\u4e00\u822c\u7684\u306b<code>=== null<\/code>\u306e\u65b9\u304c\u9ad8\u901f\u3067\u3059\u304c\u3001\u901a\u5e38\u306e\u4f7f\u7528\u3067\u306f\u5dee\u306f\u308f\u305a\u304b\u3067\u5b9f\u7528\u4e0a\u306e\u5f71\u97ff\u306f\u307b\u3068\u3093\u3069\u3042\u308a\u307e\u305b\u3093\u3002\u5927\u91cf\u30eb\u30fc\u30d7\u306a\u3069\u6975\u7aef\u306a\u30b1\u30fc\u30b9\u3067\u306e\u307f\u5dee\u304c\u9855\u8457\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u30e2\u30c0\u30f3PHP\uff08PHP 7\u4ee5\u964d\uff09\u3067\u306f\u3001\u3088\u308a\u7c21\u6f54\u306anull\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\u304c\u5c0e\u5165\u3055\u308c\u3066\u3044\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7: Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\n\/\/ null\u306e\u5834\u5408\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\n$username = $user-&gt;name ?? '\u30b2\u30b9\u30c8';\n\n\/\/ PHP 8: Nullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\n\/\/ \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cnull\u306e\u5834\u5408\u3067\u3082\u5b89\u5168\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\n$username = $user?-&gt;profile?-&gt;name;\n<\/pre>\n\n\n\n<p>\u540d\u524d\u7a7a\u9593\u3092\u4f7f\u7528\u3059\u308b\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306f\u3001\u95a2\u6570\u547c\u3073\u51fa\u3057\u3092\u6700\u9069\u5316\u3059\u308b\u305f\u3081\u306b\u3001\u5148\u982d\u306b\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4ed8\u3051\u308b\u65b9\u6cd5\u3082\u3042\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30b0\u30ed\u30fc\u30d0\u30eb\u540d\u524d\u7a7a\u9593\u304b\u3089\u76f4\u63a5\u547c\u3073\u51fa\u3057\n\\is_null($var);\n<\/pre>\n\n\n\n<p>\u6700\u9069\u89e3\u3068\u3057\u3066\u306f\u3001\u30e2\u30c0\u30f3\u306a\u74b0\u5883\u3067\u306f<code>=== null<\/code>\u304b\u3001\u9069\u5207\u306a\u5834\u5408\u306b\u306f<code>??<\/code>\u3084<code>?-&gt;<\/code>\u3092\u4f7f\u7528\u3059\u308b\u306e\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-7\">\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308b\u6319\u52d5\u306e\u9055\u3044<\/h3>\n\n\n\n<p>\u672a\u5b9a\u7fa9\u5909\u6570\uff08\u5ba3\u8a00\u3055\u308c\u3066\u3044\u306a\u3044\u5909\u6570\u3084\u3001\u5024\u304c\u4ee3\u5165\u3055\u308c\u3066\u3044\u306a\u3044\u5909\u6570\uff09\u306b\u5bfe\u3059\u308b<code>is_null()<\/code>\u3068<code>=== null<\/code>\u306e\u6319\u52d5\u306f\u3001\u5b9f\u306f\u6975\u3081\u3066\u4f3c\u3066\u3044\u307e\u3059\u3002\u4e21\u65b9\u3068\u3082\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u306a\u304c\u3089\u3082\u3001\u7d50\u679c\u7684\u306b\u306f<code>true<\/code>\u3092\u8fd4\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308b\u52d5\u4f5c\nvar_dump(is_null($undefined));\n\/\/ Warning: Undefined variable $undefined in ...\n\/\/ bool(true)\n\nvar_dump($undefined === null);\n\/\/ Warning: Undefined variable $undefined in ...\n\/\/ bool(true)\n<\/pre>\n\n\n\n<p>\u3053\u308c\u306f\u3001PHP\u304c\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u81ea\u52d5\u7684\u306b<code>null<\/code>\u5024\u3092\u5272\u308a\u5f53\u3066\u308b\u305f\u3081\u3067\u3059\u3002\u305f\u3060\u3057\u3001\u3053\u306e\u8b66\u544a\u306f\u4e88\u671f\u305b\u306c\u30d0\u30b0\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u5b9f\u7528\u7684\u306a\u5bfe\u51e6\u6cd5\u3068\u3057\u3066\u306f\u3001\u5909\u6570\u306e\u5b58\u5728\u3092\u5148\u306b\u78ba\u8a8d\u3059\u308b\u65b9\u6cd5\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b89\u5168\u306a\u65b9\u6cd5\nif (isset($var) &amp;&amp; !is_null($var)) {\n    \/\/ $var\u304c\u5b58\u5728\u3057\u3001null\u3067\u3082\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\n}\n\n\/\/ \u307e\u305f\u306f\nif (isset($var) &amp;&amp; $var !== null) {\n    \/\/ \u540c\u69d8\u306e\u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>PHP 7.4\u4ee5\u964d\u3067\u306f\u3001\u5909\u6570\u5b9a\u7fa9\u6642\u306b\u578b\u5ba3\u8a00\u3068\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f75\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u672a\u5b9a\u7fa9\u5909\u6570\u306e\u554f\u984c\u3092\u9632\u3052\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7.4\u4ee5\u964d\npublic ?string $name = null; \/\/ \u660e\u793a\u7684\u306bnull\u3067\u521d\u671f\u5316\n<\/pre>\n\n\n\n<p>\u4e21\u8005\u306e\u6a5f\u80fd\u7684\u306a\u9055\u3044\u306f\u307b\u307c\u306a\u3044\u305f\u3081\u3001\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u4e00\u8cab\u6027\u306b\u57fa\u3065\u3044\u3066\u9078\u629e\u3059\u308b\u306e\u304c\u826f\u3044\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-8\">is_null\u3001isset\u3001empty\u306e\u9055\u3044\u3092\u5fb9\u5e95\u6bd4\u8f03<\/h2>\n\n\n\n<p>PHP\u3067\u306f\u5909\u6570\u306e\u72b6\u614b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u305f\u3081\u306e\u95a2\u6570\u304c\u3044\u304f\u3064\u304b\u7528\u610f\u3055\u308c\u3066\u3044\u307e\u3059\u304c\u3001\u7279\u306b<code>is_null()<\/code>\u3001<code>isset()<\/code>\u3001<code>empty()<\/code>\u306e3\u3064\u306f\u6df7\u540c\u3055\u308c\u3084\u3059\u3044\u3082\u306e\u3067\u3059\u3002\u3053\u308c\u3089\u306f\u305d\u308c\u305e\u308c\u7570\u306a\u308b\u76ee\u7684\u3068\u52d5\u4f5c\u3092\u6301\u3063\u3066\u304a\u308a\u3001\u9069\u5207\u306a\u5834\u9762\u3067\u4f7f\u3044\u5206\u3051\u308b\u3053\u3068\u304c\u30d0\u30b0\u9632\u6b62\u306e\u9375\u3068\u306a\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u3053\u308c\u30893\u3064\u306e\u95a2\u6570\u306e\u9055\u3044\u3092\u5fb9\u5e95\u7684\u306b\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-9\">3\u3064\u306e\u95a2\u6570\u306e\u52d5\u4f5c\u539f\u7406\u3068\u8fd4\u308a\u5024<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u3001<code>isset()<\/code>\u3001<code>empty()<\/code>\u306e3\u3064\u306e\u95a2\u6570\u306f\u305d\u308c\u305e\u308c\u7570\u306a\u308b\u52d5\u4f5c\u539f\u7406\u3068\u8fd4\u308a\u5024\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u7279\u6027\u3092\u6b63\u78ba\u306b\u7406\u89e3\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-10\">is_null()<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">bool is_null(mixed $var)\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u76ee\u7684<\/strong>: \u5909\u6570\u304c\u53b3\u5bc6\u306b<code>NULL<\/code>\u5024\u3067\u3042\u308b\u304b\u3092\u5224\u5b9a\u3057\u307e\u3059<\/li>\n\n\n\n<li><strong>\u8fd4\u308a\u5024<\/strong>: \u5f15\u6570\u304c<code>NULL<\/code>\u306a\u3089\u3070<code>true<\/code>\u3001\u305d\u308c\u4ee5\u5916\u306e\u5834\u5408\u306f<code>false<\/code><\/li>\n\n\n\n<li><strong>\u5206\u985e<\/strong>: \u901a\u5e38\u306e\u95a2\u6570\uff08function\uff09<\/li>\n\n\n\n<li><strong>\u7279\u5fb4<\/strong>: \u578b\u30c1\u30a7\u30c3\u30af\u95a2\u6570\u306e\u4e00\u7a2e\u3067\u3001\u5f15\u6570\u306e\u578b\u304c<code>NULL<\/code>\u3067\u3042\u308b\u304b\u3092\u691c\u67fb<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-11\">isset()<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">bool isset(mixed $var [, mixed $...])\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u76ee\u7684<\/strong>: \u5909\u6570\u304c\u5ba3\u8a00\u3055\u308c\u3066\u3044\u3066\u3001\u304b\u3064<code>NULL<\/code>\u4ee5\u5916\u306e\u5024\u3092\u6301\u3064\u304b\u3092\u5224\u5b9a\u3057\u307e\u3059<\/li>\n\n\n\n<li><strong>\u8fd4\u308a\u5024<\/strong>: \u5f15\u6570\u304c\u5ba3\u8a00\u6e08\u307f\u3067<code>NULL<\/code>\u3067\u306a\u3051\u308c\u3070<code>true<\/code>\u3001\u305d\u3046\u3067\u306a\u3051\u308c\u3070<code>false<\/code><\/li>\n\n\n\n<li><strong>\u5206\u985e<\/strong>: \u8a00\u8a9e\u69cb\u9020\uff08language construct\uff09<\/li>\n\n\n\n<li><strong>\u7279\u5fb4<\/strong>: \u8907\u6570\u306e\u5909\u6570\u3092\u4e00\u5ea6\u306b\u30c1\u30a7\u30c3\u30af\u53ef\u80fd\u3002\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3057\u3066\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u306a\u3044<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-12\">empty()<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">bool empty(mixed $var)\n<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u76ee\u7684<\/strong>: \u5909\u6570\u304c\u300c\u7a7a\u300d\u3068\u898b\u306a\u305b\u308b\u5024\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3057\u307e\u3059<\/li>\n\n\n\n<li><strong>\u8fd4\u308a\u5024<\/strong>: \u5f15\u6570\u304c\u5b58\u5728\u3057\u306a\u3044\u304b\u300c\u7a7a\u300d(<code>\"\"<\/code>, <code>0<\/code>, <code>\"0\"<\/code>, <code>NULL<\/code>, <code>FALSE<\/code>, <code>[]<\/code>\u306a\u3069)\u306a\u3089\u3070<code>true<\/code><\/li>\n\n\n\n<li><strong>\u5206\u985e<\/strong>: \u8a00\u8a9e\u69cb\u9020\uff08language construct\uff09<\/li>\n\n\n\n<li><strong>\u7279\u5fb4<\/strong>: \u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3057\u3066\u3082\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u306a\u3044\u3002\u5e83\u3044\u7bc4\u56f2\u306e\u5024\u3092\u300c\u7a7a\u300d\u3068\u898b\u306a\u3059<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-13\">\u5b9f\u969b\u306e\u52d5\u4f5c\u6bd4\u8f03<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u69d8\u3005\u306a\u5024\u3067\u306e\u52d5\u4f5c\u6bd4\u8f03\n$values = [\n    'undefined' =&gt; @$undefined, \/\/ \u672a\u5b9a\u7fa9\u5909\u6570\uff08\u30a8\u30e9\u30fc\u6291\u5236\uff09\n    'null' =&gt; null,\n    'empty_string' =&gt; \"\",\n    'zero_string' =&gt; \"0\",\n    'zero' =&gt; 0,\n    'false' =&gt; false,\n    'empty_array' =&gt; [],\n    'text' =&gt; \"hello\",\n    'number' =&gt; 42,\n    'array' =&gt; [1, 2, 3]\n];\n\nforeach ($values as $key =&gt; $value) {\n    echo \"$key: \";\n    echo \"is_null() = \" . (is_null($value) ? 'true' : 'false') . ', ';\n    echo \"isset() = \" . (isset($value) ? 'true' : 'false') . ', ';\n    echo \"empty() = \" . (empty($value) ? 'true' : 'false');\n    echo \"\\n\";\n}\n<\/pre>\n\n\n\n<p><code>isset()<\/code>\u3068<code>empty()<\/code>\u306f\u8a00\u8a9e\u69cb\u9020\u3067\u3042\u308b\u305f\u3081\u3001\u95a2\u6570\u547c\u3073\u51fa\u3057\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u767a\u751f\u305b\u305a\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u9762\u3067\u512a\u308c\u3066\u3044\u307e\u3059\u3002\u4e00\u65b9\u3001<code>is_null()<\/code>\u306f\u901a\u5e38\u306e\u95a2\u6570\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-14\">\u5b9f\u7528\u30b7\u30fc\u30f3\u306b\u5fdc\u3058\u305f\u4f7f\u3044\u5206\u3051\u306e\u5224\u65ad\u57fa\u6e96<\/h3>\n\n\n\n<p>3\u3064\u306e\u95a2\u6570\u306e\u7279\u6027\u3092\u7406\u89e3\u3057\u305f\u3068\u3053\u308d\u3067\u3001\u5b9f\u969b\u306e\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b7\u30fc\u30f3\u306b\u304a\u3051\u308b\u9069\u5207\u306a\u4f7f\u3044\u5206\u3051\u3092\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u72b6\u6cc1\u306b\u5fdc\u3058\u305f\u6700\u9069\u306a\u9078\u629e\u80a2\u3092\u5224\u65ad\u3059\u308b\u305f\u3081\u306e\u57fa\u6e96\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-15\">\u5909\u6570\u306e\u5b58\u5728\u78ba\u8a8d\u304c\u5fc5\u8981\u306a\u5834\u5408<\/h4>\n\n\n\n<p>\u5909\u6570\u304c\u5ba3\u8a00\u3055\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3057\u305f\u3044\u5834\u5408\u306f\u3001<code>isset()<\/code>\u304c\u6700\u9069\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u304b\u3089\u306ePOST\u30c7\u30fc\u30bf\u3092\u5b89\u5168\u306b\u53d6\u5f97\nif (isset($_POST['username'])) {\n    $username = $_POST['username'];\n} else {\n    $username = '\u30b2\u30b9\u30c8';\n}\n\n\/\/ \u914d\u5217\u306e\u30ad\u30fc\u304c\u5b58\u5728\u3059\u308b\u304b\u30c1\u30a7\u30c3\u30af\n$user = ['name' =&gt; 'John', 'email' =&gt; 'john@example.com'];\nif (isset($user['age'])) {\n    echo \"\u5e74\u9f62: {$user['age']}\";\n} else {\n    echo \"\u5e74\u9f62\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-16\">\u53b3\u5bc6\u306bNULL\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3059\u308b\u5834\u5408<\/h4>\n\n\n\n<p>\u5909\u6570\u304c\u65e2\u306b\u5b58\u5728\u3059\u308b\u3053\u3068\u304c\u308f\u304b\u3063\u3066\u3044\u3066\u3001\u305d\u306e\u5024\u304c\u53b3\u5bc6\u306b<code>NULL<\/code>\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3059\u308b\u5834\u5408\u306f<code>is_null()<\/code>\u304c\u9069\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u53d6\u5f97\u3057\u305f\u5024\u304cNULL\u304b\u30c1\u30a7\u30c3\u30af\n$result = $db-&gt;query(\"SELECT birth_date FROM users WHERE id = 1\");\n$birthDate = $result-&gt;fetch();\n\nif (is_null($birthDate)) {\n    echo \"\u751f\u5e74\u6708\u65e5\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u751f\u5e74\u6708\u65e5: $birthDate\";\n}\n\n\/\/ \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u304cNULL\u304b\u30c1\u30a7\u30c3\u30af\nif (is_null($user-&gt;address)) {\n    echo \"\u4f4f\u6240\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-17\">\u300c\u7a7a\u300d\u306e\u5024\u3092\u5e83\u304f\u5224\u5b9a\u3057\u305f\u3044\u5834\u5408<\/h4>\n\n\n\n<p>\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3084\u30d5\u30a9\u30fc\u30e0\u30c7\u30fc\u30bf\u306a\u3069\u3001\u69d8\u3005\u306a\u300c\u7a7a\u300d\u306e\u72b6\u614b\uff08\u7a7a\u6587\u5b57\u30010\u3001false\u3001\u7a7a\u914d\u5217\u306a\u3069\uff09\u3092\u4e00\u62ec\u3067\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044\u5834\u5408\u306f<code>empty()<\/code>\u304c\u4fbf\u5229\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u5fc5\u9808\u9805\u76ee\u30c1\u30a7\u30c3\u30af\nif (empty($_POST['email'])) {\n    echo \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306f\u5fc5\u9808\u9805\u76ee\u3067\u3059\";\n}\n\n\/\/ \u691c\u7d22\u7d50\u679c\u304c\u7a7a\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\n$searchResults = search($query);\nif (empty($searchResults)) {\n    echo \"\u691c\u7d22\u7d50\u679c\u306f\u3042\u308a\u307e\u305b\u3093\u3067\u3057\u305f\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-18\">\u8907\u5408\u7684\u306a\u6761\u4ef6\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<p>\u3088\u308a\u8907\u96d1\u306a\u30b1\u30fc\u30b9\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u95a2\u6570\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5909\u6570\u304c\u5b58\u5728\u3057\u3001\u7a7a\u3067\u306a\u3044\u5834\u5408\u306e\u307f\u51e6\u7406\nif (isset($data) &amp;&amp; !empty($data)) {\n    processData($data);\n}\n\n\/\/ \u5909\u6570\u304c\u5b58\u5728\u3057\u3001NULL\u3067\u306a\u3044\u5834\u5408\u306e\u307f\u51e6\u7406\nif (isset($config) &amp;&amp; !is_null($config)) {\n    loadConfiguration($config);\n}\n<\/pre>\n\n\n\n<p>\u57fa\u672c\u7684\u306a\u5224\u65ad\u57fa\u6e96\u3068\u3057\u3066\u306f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5909\u6570\u306e\u5b58\u5728\u78ba\u8a8d\uff08\u672a\u5b9a\u7fa9\u5909\u6570\u306e\u56de\u907f\uff09\u2192 <code>isset()<\/code><\/li>\n\n\n\n<li>\u53b3\u5bc6\u306aNULL\u5024\u306e\u30c1\u30a7\u30c3\u30af \u2192 <code>is_null()<\/code>\u307e\u305f\u306f<code>$var === null<\/code><\/li>\n\n\n\n<li>\u5e83\u7fa9\u306e\u300c\u7a7a\u300d\u30c1\u30a7\u30c3\u30af\uff08\u30d5\u30a9\u30fc\u30e0\u691c\u8a3c\u306a\u3069\uff09\u2192 <code>empty()<\/code><\/li>\n<\/ul>\n\n\n\n<p>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u4e00\u8cab\u6027\u3092\u4fdd\u3064\u305f\u3081\u306b\u3001\u30c1\u30fc\u30e0\u5185\u3067\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u898f\u7d04\u3092\u5b9a\u3081\u308b\u306e\u3082\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-19\">\u6bd4\u8f03\u8868\u3067\u5206\u304b\u308b\u52d5\u4f5c\u306e\u9055\u3044<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u3001<code>isset()<\/code>\u3001<code>empty()<\/code>\u306e\u6319\u52d5\u306e\u9055\u3044\u3092\u8996\u899a\u7684\u306b\u7406\u89e3\u3059\u308b\u305f\u3081\u306b\u3001\u69d8\u3005\u306a\u5165\u529b\u5024\u306b\u5bfe\u3059\u308b\u7d50\u679c\u3092\u6bd4\u8f03\u8868\u306b\u307e\u3068\u3081\u307e\u3057\u305f\u3002\u3053\u306e\u8868\u3092\u53c2\u8003\u306b\u3059\u308b\u3053\u3068\u3067\u3001\u305d\u308c\u305e\u308c\u306e\u95a2\u6570\u304c\u3069\u306e\u3088\u3046\u306a\u72b6\u6cc1\u3067\u3069\u306e\u3088\u3046\u306a\u7d50\u679c\u3092\u8fd4\u3059\u306e\u304b\u3092\u4e00\u76ee\u3067\u628a\u63e1\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n<div id=\"id-ab469ae4-e0d1-4c08-8ff0-67a8f6ffc1e8\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u5165\u529b\u5024<\/th><th>is_null()<\/th><th>isset()<\/th><th>empty()<\/th><th>\u30b3\u30e1\u30f3\u30c8<\/th><\/tr><\/thead><tbody><tr><td>\u672a\u5b9a\u7fa9\u5909\u6570 ($undefined)<\/td><td>Warning + true<\/td><td>false<\/td><td>true<\/td><td>isset()\u3068empty()\u306f\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u306a\u3044<\/td><\/tr><tr><td>null<\/td><td>true<\/td><td>false<\/td><td>true<\/td><td>3\u3064\u306e\u95a2\u6570\u3067\u4e00\u756a\u9055\u3044\u304c\u660e\u78ba\u306b\u306a\u308b\u30b1\u30fc\u30b9<\/td><\/tr><tr><td>\u201c\u201d\uff08\u7a7a\u6587\u5b57\uff09<\/td><td>false<\/td><td>true<\/td><td>true<\/td><td>empty()\u306f\u7a7a\u6587\u5b57\u3092\u300c\u7a7a\u300d\u3068\u5224\u5b9a<\/td><\/tr><tr><td>\u201c0\u201d\uff08\u6587\u5b57\u5217\u306e0\uff09<\/td><td>false<\/td><td>true<\/td><td>true<\/td><td>PHP\u3067\u306f\u201d0\u2033\u3082\u300c\u7a7a\u300d\u3068\u5224\u5b9a\u3055\u308c\u308b<\/td><\/tr><tr><td>0\uff08\u6570\u5024\uff09<\/td><td>false<\/td><td>true<\/td><td>true<\/td><td>empty()\u306f\u6570\u5024\u306e0\u3082\u300c\u7a7a\u300d\u3068\u5224\u5b9a<\/td><\/tr><tr><td>false<\/td><td>false<\/td><td>true<\/td><td>true<\/td><td>\u8ad6\u7406\u5024\u306efalse\u3082\u300c\u7a7a\u300d\u3068\u5224\u5b9a<\/td><\/tr><tr><td>[]\uff08\u7a7a\u914d\u5217\uff09<\/td><td>false<\/td><td>true<\/td><td>true<\/td><td>\u7a7a\u914d\u5217\u3082\u300c\u7a7a\u300d\u3068\u5224\u5b9a<\/td><\/tr><tr><td>\u201cabc\u201d\uff08\u6587\u5b57\u5217\uff09<\/td><td>false<\/td><td>true<\/td><td>false<\/td><td>\u901a\u5e38\u306e\u6587\u5b57\u5217\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044<\/td><\/tr><tr><td>1\uff08\u6570\u5024\uff09<\/td><td>false<\/td><td>true<\/td><td>false<\/td><td>0\u4ee5\u5916\u306e\u6570\u5024\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044<\/td><\/tr><tr><td>[1,2,3]\uff08\u914d\u5217\uff09<\/td><td>false<\/td><td>true<\/td><td>false<\/td><td>\u8981\u7d20\u3092\u6301\u3064\u914d\u5217\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044<\/td><\/tr><tr><td>new stdClass()<\/td><td>false<\/td><td>true<\/td><td>false<\/td><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u30d7\u30ed\u30d1\u30c6\u30a3\u306e\u6709\u7121\u306b\u95a2\u308f\u3089\u305a\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<p>\u3053\u306e\u8868\u304b\u3089\u8aad\u307f\u53d6\u308c\u308b\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>is_null()<\/code>\u306f\u53b3\u5bc6\u306b<code>NULL<\/code>\u5024\u306e\u307f\u3092<code>true<\/code>\u3068\u5224\u5b9a<\/li>\n\n\n\n<li><code>isset()<\/code>\u306f\u5909\u6570\u304c\u5ba3\u8a00\u3055\u308c\u3066\u3044\u3066<code>NULL<\/code>\u3067\u306a\u3051\u308c\u3070\u5e38\u306b<code>true<\/code><\/li>\n\n\n\n<li><code>empty()<\/code>\u306f\u6700\u3082\u5e83\u3044\u7bc4\u56f2\u306e\u5024\u3092\u300c\u7a7a\u300d\u3068\u3057\u3066<code>true<\/code>\u3068\u5224\u5b9a<\/li>\n\n\n\n<li>\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3057\u3066\u3001<code>isset()<\/code>\u306f<code>false<\/code>\u3001<code>empty()<\/code>\u306f<code>true<\/code>\u3001<code>is_null()<\/code>\u306f\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u3064\u3064<code>true<\/code>\u3092\u8fd4\u3059<\/li>\n<\/ol>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u6319\u52d5\u306e\u9055\u3044\u3092\u7406\u89e3\u3057\u3066\u3044\u306a\u3044\u3068\u3001\u4e88\u671f\u305b\u306c\u30d0\u30b0\u304c\u767a\u751f\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u7279\u306b\u3001\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u5024\u306e\u691c\u8a3c\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u53d6\u5f97\u3057\u305f\u5024\u306e\u51e6\u7406\u306a\u3069\u3001\u5024\u304c<code>null<\/code>\u3084\u7a7a\u306e\u53ef\u80fd\u6027\u304c\u3042\u308b\u5834\u5408\u306b\u306f\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<p>\u4f8b\u3048\u3070\u3001<code>\"0\"<\/code>\uff08\u6587\u5b57\u5217\u306e\u30bc\u30ed\uff09\u306f\u591a\u304f\u306e\u5834\u5408\u6709\u52b9\u306a\u5165\u529b\u5024\u3067\u3059\u304c\u3001<code>empty()<\/code>\u3067\u306f\u300c\u7a7a\u300d\u3068\u5224\u5b9a\u3055\u308c\u308b\u305f\u3081\u3001\u5358\u7d14\u306b<code>empty()<\/code>\u3060\u3051\u3092\u4f7f\u7528\u3057\u305f\u5165\u529b\u691c\u8a3c\u3067\u306f\u4e88\u671f\u305b\u306c\u52d5\u4f5c\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$value = \"0\"; \/\/ \u4f8b\u3048\u3070\u96fb\u8a71\u756a\u53f7\u306e\u5e02\u5916\u5c40\u756a\u306a\u3069\nif (empty($value)) {\n    echo \"\u5024\u304c\u7a7a\u3067\u3059\"; \/\/ \"0\"\u306f\u7a7a\u3068\u5224\u5b9a\u3055\u308c\u308b\u306e\u3067\u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n} else {\n    echo \"\u5024\u304c\u3042\u308a\u307e\u3059\";\n}\n<\/pre>\n\n\n\n<p>\u3053\u306e\u3088\u3046\u306a\u5834\u5408\u306f\u3001\u3088\u308a\u53b3\u5bc6\u306a\u6761\u4ef6\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-20\">is_null\u95a2\u6570\u306e\u6d3b\u7528\u30b7\u30fc\u30f3\u5225\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306f\u5358\u7d14\u3067\u3059\u304c\u3001\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u30b3\u30fc\u30c9\u306e\u4fe1\u983c\u6027\u3068\u53ef\u8aad\u6027\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u69d8\u3005\u306a\u5b9f\u8df5\u30b7\u30fc\u30f3\u306b\u304a\u3051\u308b<code>is_null()<\/code>\u95a2\u6570\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528\u65b9\u6cd5\u3068\u3001\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002\u5b9f\u969b\u306e\u30b3\u30fc\u30c9\u4f8b\u3092\u4ea4\u3048\u306a\u304c\u3089\u3001\u3088\u308a\u5805\u7262\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u306e\u305f\u3081\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-21\">\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u5024\u306e\u691c\u8a3c\u3067\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/h3>\n\n\n\n<p>Web\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u30d5\u30a9\u30fc\u30e0\u304b\u3089\u306e\u5165\u529b\u5024\u3092\u9069\u5207\u306b\u691c\u8a3c\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<code>is_null()<\/code>\u95a2\u6570\u3092\u4f7f\u3063\u305f\u52b9\u679c\u7684\u306a\u5165\u529b\u691c\u8a3c\u65b9\u6cd5\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-22\">\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u5024\u306eNULL\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<p>\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u5024\u3092\u51e6\u7406\u3059\u308b\u969b\u3001\u7279\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u306a\u306e\u306f\u300c\u5b58\u5728\u3059\u308b\u304c\u7a7a\u300d\u3068\u300c\u5b8c\u5168\u306b\u5b58\u5728\u3057\u306a\u3044\uff08NULL\uff09\u300d\u306e\u533a\u5225\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u9001\u4fe1\u5f8c\u306e\u51e6\u7406\nfunction processForm() {\n    \/\/ \u5b58\u5728\u30c1\u30a7\u30c3\u30af\u3068NULL\u30c1\u30a7\u30c3\u30af\u306e\u7d44\u307f\u5408\u308f\u305b\n    if (!isset($_POST['email'])) {\n        return \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u9001\u4fe1\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n    }\n    \n    if (is_null($_POST['email'])) {\n        return \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u304cNULL\u3067\u3059\";\n    }\n    \n    if ($_POST['email'] === '') {\n        return \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    \/\/ \u6b63\u5e38\u306a\u51e6\u7406\n    $email = $_POST['email'];\n    \/\/ ...\n}\n<\/pre>\n\n\n\n<p>\u305f\u3060\u3057\u3001\u901a\u5e38\u306eHTML\u30d5\u30a9\u30fc\u30e0\u3067\u306f\u3001\u672a\u5165\u529b\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u7a7a\u6587\u5b57\u3068\u3057\u3066\u9001\u4fe1\u3055\u308c\u308b\u3053\u3068\u304c\u591a\u304f\u3001<code>NULL<\/code>\u5024\u304c\u9001\u3089\u308c\u308b\u3053\u3068\u306f\u7a00\u3067\u3059\u3002\u305d\u306e\u305f\u3081\u3001\u5b9f\u7528\u7684\u306b\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u66f8\u304d\u65b9\u304c\u3088\u308a\u4e00\u822c\u7684\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u3088\u308a\u5b9f\u7528\u7684\u306a\u30a2\u30d7\u30ed\u30fc\u30c1\nfunction validateEmail($email) {\n    if (!isset($email) || $email === '') {\n        return \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    \/\/ \u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306e\u5f62\u5f0f\u691c\u8a3c\n    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {\n        return \"\u6709\u52b9\u306a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    return true; \/\/ \u691c\u8a3c\u6210\u529f\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$validation = validateEmail($_POST['email'] ?? null);\nif ($validation !== true) {\n    echo $validation; \/\/ \u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u8868\u793a\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-23\">API\u3084JSON\u30c7\u30fc\u30bf\u306e\u51e6\u7406<\/h4>\n\n\n\n<p>API\u3084JSON\u30c7\u30fc\u30bf\u3092\u6271\u3046\u5834\u5408\u306f\u3001<code>NULL<\/code>\u5024\u304c\u660e\u793a\u7684\u306b\u542b\u307e\u308c\u3066\u3044\u308b\u3053\u3068\u304c\u591a\u3044\u305f\u3081\u3001<code>is_null()<\/code>\u304c\u6709\u52b9\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ JSON\u30c7\u30fc\u30bf\u306e\u51e6\u7406\n$jsonData = json_decode($response, true);\n\n\/\/ \u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u306e\u691c\u8a3c\nif (is_null($jsonData['user'])) {\n    echo \"\u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u304c\u3042\u308a\u307e\u305b\u3093\";\n    return;\n}\n\n\/\/ Null\u304c\u8a31\u5bb9\u3055\u308c\u308b\u9805\u76ee\u306e\u51e6\u7406\n$birthdate = $jsonData['user']['birthdate'];\nif (is_null($birthdate)) {\n    echo \"\u751f\u5e74\u6708\u65e5\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u751f\u5e74\u6708\u65e5: \" . formatDate($birthdate);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-24\">\u30aa\u30d7\u30b7\u30e7\u30ca\u30eb\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u691c\u8a3c<\/h4>\n\n\n\n<p>\u30d5\u30a9\u30fc\u30e0\u3084API\u3067\u30aa\u30d7\u30b7\u30e7\u30ca\u30eb\u30d1\u30e9\u30e1\u30fc\u30bf\u3092\u6271\u3046\u5834\u5408\u3001\u4e0d\u5728\uff08\u672a\u9001\u4fe1\uff09\u3068NULL\u306e\u4e21\u65b9\u3092\u8003\u616e\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30aa\u30d7\u30b7\u30e7\u30ca\u30eb\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u51e6\u7406\nfunction processOptionalParam($param = null) {\n    \/\/ \u30d1\u30e9\u30e1\u30fc\u30bf\u304c\u660e\u793a\u7684\u306bNULL\u3068\u3057\u3066\u6e21\u3055\u308c\u305f\u5834\u5408\n    if (is_null($param)) {\n        return \"\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3057\u307e\u3059\";\n    }\n    \n    \/\/ \u30d1\u30e9\u30e1\u30fc\u30bf\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306e\u51e6\u7406\n    return \"\u30d1\u30e9\u30e1\u30fc\u30bf\u5024: $param\";\n}\n\n\/\/ \u4f7f\u7528\u4f8b\necho processOptionalParam(); \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3057\u307e\u3059\necho processOptionalParam(null); \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3057\u307e\u3059\necho processOptionalParam(\"test\"); \/\/ \u30d1\u30e9\u30e1\u30fc\u30bf\u5024: test\n<\/pre>\n\n\n\n<p>\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u3067\u306f\u3001<code>is_null()<\/code>\u3088\u308a\u3082<code>isset()<\/code>\u3084<code>empty()<\/code>\u306e\u65b9\u304c\u9069\u3057\u3066\u3044\u308b\u5834\u5408\u304c\u591a\u3044\u3067\u3059\u304c\u3001JSON\u30c7\u30fc\u30bf\u3084API\u30ec\u30b9\u30dd\u30f3\u30b9\u306a\u3069\u3001\u660e\u793a\u7684\u306bNULL\u5024\u3092\u6271\u3046\u5834\u9762\u3067\u306f<code>is_null()<\/code>\u304c\u91cd\u8981\u306a\u5f79\u5272\u3092\u679c\u305f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-25\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u306b\u304a\u3051\u308b\u6d3b\u7528\u65b9\u6cd5<\/h3>\n\n\n\n<p>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u3067\u306fNULL\u5024\u304c\u983b\u7e41\u306b\u767b\u5834\u3057\u307e\u3059\u3002SQL\u306eNULL\u3068PHP\u306enull\u306f\u6982\u5ff5\u7684\u306b\u4e00\u81f4\u3057\u3066\u304a\u308a\u3001<code>is_null()<\/code>\u95a2\u6570\u3092\u4f7f\u3046\u3053\u3068\u3067\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u53d6\u5f97\u3057\u305f\u5024\u3092\u9069\u5207\u306b\u51e6\u7406\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-26\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u53d6\u5f97\u7d50\u679c\u306eNULL\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u3092\u53d6\u5f97\u3059\u308b\u4f8b\n$stmt = $pdo-&gt;prepare(\"SELECT name, email, phone, birth_date FROM users WHERE id = ?\");\n$stmt-&gt;execute([$userId]);\n$user = $stmt-&gt;fetch(PDO::FETCH_ASSOC);\n\n\/\/ \u96fb\u8a71\u756a\u53f7\u304cNULL\u304b\u30c1\u30a7\u30c3\u30af\uff08\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u3067NULLABLE\uff09\nif (is_null($user['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u96fb\u8a71\u756a\u53f7: \" . $user['phone'];\n}\n\n\/\/ \u751f\u5e74\u6708\u65e5\u306e\u8868\u793a\uff08NULL\u306e\u5834\u5408\u306f\u4ee3\u66ff\u30c6\u30ad\u30b9\u30c8\uff09\necho \"\u751f\u5e74\u6708\u65e5: \" . (is_null($user['birth_date']) ? \"\u672a\u767b\u9332\" : formatDate($user['birth_date']));\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-27\">INSERT\/UPDATE\u6587\u3067\u306eNULL\u5024\u306e\u9069\u5207\u306a\u6271\u3044<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u304b\u3089\u306e\u30c7\u30fc\u30bf\u3092\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306b\u4fdd\u5b58\nfunction saveUserData($userData) {\n    $pdo = getDbConnection();\n    \n    \/\/ \u660e\u793a\u7684\u306bNULL\u3068\u3057\u3066\u4fdd\u5b58\u3057\u305f\u3044\u5834\u5408\uff08\u7701\u7565\u53ef\u80fd\u9805\u76ee\uff09\n    $phone = empty($userData['phone']) ? null : $userData['phone'];\n    \n    \/\/ \u30d7\u30ea\u30da\u30a2\u30c9\u30b9\u30c6\u30fc\u30c8\u30e1\u30f3\u30c8\u3067NULL\u5024\u3092\u9069\u5207\u306b\u6271\u3046\n    $stmt = $pdo-&gt;prepare(\"\n        INSERT INTO users (name, email, phone) \n        VALUES (:name, :email, :phone)\n    \");\n    \n    $stmt-&gt;bindParam(':name', $userData['name']);\n    $stmt-&gt;bindParam(':email', $userData['email']);\n    $stmt-&gt;bindParam(':phone', $phone, PDO::PARAM_STR);\n    \n    return $stmt-&gt;execute();\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-28\">\u691c\u7d22\u6761\u4ef6\u3067\u306eNULL\u5024\u51e6\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ NULL\u3092\u542b\u3080\u691c\u7d22\u6761\u4ef6\u306e\u69cb\u7bc9\nfunction buildSearchQuery($filters) {\n    $conditions = [];\n    $params = [];\n    \n    \/\/ \u5404\u30d5\u30a3\u30eb\u30bf\u30fc\u6761\u4ef6\u3092\u51e6\u7406\n    foreach ($filters as $field =&gt; $value) {\n        \/\/ NULL\u306e\u5834\u5408\u306f IS NULL \u6761\u4ef6\u3092\u4f7f\u7528\n        if (is_null($value)) {\n            $conditions[] = \"$field IS NULL\";\n        } \n        \/\/ NULL\u3067\u306f\u306a\u3044\u5834\u5408\u306f\u901a\u5e38\u306e\u7b49\u4fa1\u6761\u4ef6\n        else {\n            $conditions[] = \"$field = :$field\";\n            $params[\":$field\"] = $value;\n        }\n    }\n    \n    \/\/ \u6761\u4ef6\u304c1\u3064\u4ee5\u4e0a\u3042\u308b\u5834\u5408\u306f WHERE \u53e5\u3092\u8ffd\u52a0\n    $sql = \"SELECT * FROM users\";\n    if (!empty($conditions)) {\n        $sql .= \" WHERE \" . implode(\" AND \", $conditions);\n    }\n    \n    return ['sql' =&gt; $sql, 'params' =&gt; $params];\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$query = buildSearchQuery([\n    'status' =&gt; 'active',\n    'deleted_at' =&gt; null  \/\/ \u524a\u9664\u3055\u308c\u3066\u3044\u306a\u3044\u30ec\u30b3\u30fc\u30c9\n]);\n\n$stmt = $pdo-&gt;prepare($query['sql']);\n$stmt-&gt;execute($query['params']);\n$results = $stmt-&gt;fetchAll();\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-29\">\u7d50\u679c\u30bb\u30c3\u30c8\u304c\u7a7a\u306e\u5834\u5408\u306e\u51e6\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u691c\u7d22\u7d50\u679c\u304c\u7a7a\u306e\u5834\u5408\u306e\u51e6\u7406\n$stmt = $pdo-&gt;prepare(\"SELECT * FROM products WHERE category = ?\");\n$stmt-&gt;execute([$category]);\n$product = $stmt-&gt;fetch(PDO::FETCH_ASSOC);\n\n\/\/ \u691c\u7d22\u7d50\u679c\u304c\u306a\u3044\u5834\u5408\u306f false \u304c\u8fd4\u308b\u306e\u3067\u6ce8\u610f\nif ($product === false) {\n    echo \"\u88fd\u54c1\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\u3067\u3057\u305f\";\n} \n\/\/ \u691c\u7d22\u7d50\u679c\u304c\u3042\u3063\u3066\u3082\u30ab\u30e9\u30e0\u304cNULL\u306e\u5834\u5408\u306e\u51e6\u7406\nelse if (is_null($product['description'])) {\n    echo \"\u88fd\u54c1\u8aac\u660e\u306f\u3042\u308a\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<p>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u3067\u306f\u3001<code>is_null()<\/code>\u3092\u4f7f\u3063\u3066 NULL \u5024\u3092\u9069\u5207\u306b\u51e6\u7406\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u69cb\u7bc9\u3067\u304d\u307e\u3059\u3002\u7279\u306b\u7701\u7565\u53ef\u80fd\u306a\u30d5\u30a3\u30fc\u30eb\u30c9\u3084\u691c\u7d22\u6761\u4ef6\u3092\u6271\u3046\u969b\u306b\u306f\u3001NULL \u5024\u306e\u5224\u5b9a\u304c\u91cd\u8981\u306a\u5f79\u5272\u3092\u679c\u305f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-30\">\u6761\u4ef6\u5206\u5c90\u3067\u306e\u52b9\u679c\u7684\u306a\u4f7f\u7528\u4f8b<\/h3>\n\n\n\n<p>\u6761\u4ef6\u5206\u5c90\u306f\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u5b9f\u884c\u30d5\u30ed\u30fc\u3092\u5236\u5fa1\u3059\u308b\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002<code>is_null()<\/code>\u95a2\u6570\u3092\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u660e\u78ba\u3067\u5805\u7262\u306a\u6761\u4ef6\u5206\u5c90\u3092\u5b9f\u88c5\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-31\">\u57fa\u672c\u7684\u306a\u6761\u4ef6\u5206\u5c90\u3067\u306e\u4f7f\u7528\u6cd5<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e6\u30fc\u30b6\u30fc\u8a2d\u5b9a\u306b\u57fa\u3065\u304f\u6761\u4ef6\u5206\u5c90\nfunction getUserPreference($userId, $key) {\n    $preference = fetchUserPreference($userId, $key);\n    \n    \/\/ \u8a2d\u5b9a\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\uff08NULL\uff09\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\n    if (is_null($preference)) {\n        return getDefaultPreference($key);\n    }\n    \n    return $preference;\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-32\">Null\u72b6\u614b\u306b\u5fdc\u3058\u305f\u51e6\u7406\u306e\u5206\u5c90<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e6\u30fc\u30b6\u30fc\u306e\u30d7\u30ed\u30d5\u30a3\u30fc\u30eb\u753b\u50cf\u51e6\u7406\nfunction getUserProfileImage($user) {\n    \/\/ \u30d7\u30ed\u30d5\u30a3\u30fc\u30eb\u753b\u50cf\u304cnull\u306e\u5834\u5408\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u753b\u50cf\u3092\u4f7f\u7528\n    if (is_null($user-&gt;profile_image)) {\n        return '\/images\/default-avatar.png';\n    }\n    \n    \/\/ \u753b\u50cf\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u306f\u305d\u306eURL\u3092\u8fd4\u3059\n    return $user-&gt;profile_image;\n}\n\n\/\/ \u8868\u793a\u4f8b\necho '&lt;img src=\"' . getUserProfileImage($currentUser) . '\" alt=\"Profile\"&gt;';\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-33\">\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u305f\u7c21\u6f54\u306a\u6761\u4ef6\u5206\u5c90<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u305f\u7c21\u6f54\u306a\u66f8\u304d\u65b9\nfunction getDisplayName($user) {\n    \/\/ \u30d5\u30eb\u30cd\u30fc\u30e0\u304cnull\u306e\u5834\u5408\u306f\u30e6\u30fc\u30b6\u30fc\u540d\u3092\u8868\u793a\n    $displayName = is_null($user-&gt;full_name) ? $user-&gt;username : $user-&gt;full_name;\n    return $displayName;\n}\n\n\/\/ \u3088\u308a\u8907\u96d1\u306a\u6761\u4ef6\u5206\u5c90\u3082\u7c21\u6f54\u306b\u66f8\u3051\u308b\n$message = is_null($result) \n    ? \"\u30c7\u30fc\u30bf\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\u3067\u3057\u305f\" \n    : \"\u51e6\u7406\u7d50\u679c: \" . $result;\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-34\">\u9023\u7d9a\u3057\u305f\u6761\u4ef6\u30c1\u30a7\u30c3\u30af\u3067\u306e\u4f7f\u7528<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u9806\u6b21\u6761\u4ef6\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u4f8b\nfunction getContactInfo($user) {\n    \/\/ \u512a\u5148\u5ea6\u9806\u306b\u9023\u7d61\u5148\u60c5\u5831\u3092\u30c1\u30a7\u30c3\u30af\n    if (!is_null($user-&gt;mobile_phone)) {\n        return $user-&gt;mobile_phone;\n    }\n    \n    if (!is_null($user-&gt;office_phone)) {\n        return $user-&gt;office_phone;\n    }\n    \n    if (!is_null($user-&gt;home_phone)) {\n        return $user-&gt;home_phone;\n    }\n    \n    if (!is_null($user-&gt;email)) {\n        return $user-&gt;email;\n    }\n    \n    \/\/ \u9023\u7d61\u5148\u60c5\u5831\u304c\u306a\u3044\u5834\u5408\n    return \"\u9023\u7d61\u5148\u60c5\u5831\u304c\u3042\u308a\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-35\">\u8907\u6570\u6761\u4ef6\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u8907\u5408\u6761\u4ef6\u3067\u306e\u4f7f\u7528\u4f8b\nfunction validateProduct($product) {\n    \/\/ \u5fc5\u9808\u9805\u76ee\u304c\u5168\u3066\u5165\u529b\u3055\u308c\u3066\u3044\u308b\u304b\u78ba\u8a8d\n    if (is_null($product-&gt;name) || is_null($product-&gt;price) || is_null($product-&gt;category)) {\n        return \"\u5fc5\u9808\u9805\u76ee\uff08\u5546\u54c1\u540d\u3001\u4fa1\u683c\u3001\u30ab\u30c6\u30b4\u30ea\uff09\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    \/\/ \u4fa1\u683c\u306e\u7bc4\u56f2\u30c1\u30a7\u30c3\u30af\n    if ($product-&gt;price &lt;= 0) {\n        return \"\u4fa1\u683c\u306f0\u3088\u308a\u5927\u304d\u3044\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    \/\/ \u8aac\u660e\u6587\u306fnull\u3067\u3082\u826f\u3044\u304c\u3001\u5165\u529b\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u306f10\u6587\u5b57\u4ee5\u4e0a\u5fc5\u8981\n    if (!is_null($product-&gt;description) &amp;&amp; strlen($product-&gt;description) &lt; 10) {\n        return \"\u8aac\u660e\u6587\u306f10\u6587\u5b57\u4ee5\u4e0a\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    return true; \/\/ \u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u6210\u529f\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-36\">Null\u8a31\u5bb9\u578b\uff08PHP 7.1\u4ee5\u964d\uff09\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7.1\u4ee5\u964d\u306eNull\u8a31\u5bb9\u578b\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\nfunction processData(?string $input): string {\n    \/\/ \u5f15\u6570\u304cnull\u306e\u5834\u5408\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u51e6\u7406\n    if (is_null($input)) {\n        return \"No data provided\";\n    }\n    \n    \/\/ \u901a\u5e38\u306e\u51e6\u7406\n    return \"Processing: \" . $input;\n}\n\n\/\/ \u547c\u3073\u51fa\u3057\u4f8b\necho processData(null);      \/\/ \"No data provided\"\necho processData(\"Test\");    \/\/ \"Processing: Test\"\n<\/pre>\n\n\n\n<p>\u6761\u4ef6\u5206\u5c90\u3067\u306e<code>is_null()<\/code>\u306e\u4f7f\u7528\u306f\u3001\u30b3\u30fc\u30c9\u306e\u610f\u56f3\u3092\u660e\u78ba\u306b\u8868\u73fe\u3057\u3001NULL\u306b\u95a2\u9023\u3059\u308b\u30a8\u30e9\u30fc\u3092\u9632\u3050\u306e\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002\u7279\u306b\u300c\u5024\u304c\u306a\u3044\u300d\u72b6\u614b\u3068\u300c\u7a7a\u306e\u5024\u300d\u3092\u660e\u78ba\u306b\u533a\u5225\u3057\u305f\u3044\u5834\u5408\u306b\u6709\u52b9\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-37\">\u95a2\u6570\u306e\u5f15\u6570\u30c1\u30a7\u30c3\u30af\u3067\u306e\u5fdc\u7528<\/h3>\n\n\n\n<p>\u95a2\u6570\u306e\u5f15\u6570\u3092\u9069\u5207\u306b\u691c\u8a3c\u3059\u308b\u3053\u3068\u306f\u3001\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306b\u4e0d\u53ef\u6b20\u3067\u3059\u3002<code>is_null()<\/code>\u95a2\u6570\u306f\u3001\u95a2\u6570\u306e\u5f15\u6570\u30c1\u30a7\u30c3\u30af\u306b\u304a\u3044\u3066\u91cd\u8981\u306a\u5f79\u5272\u3092\u679c\u305f\u3057\u307e\u3059\u3002\u4ee5\u4e0b\u306b\u3001\u3055\u307e\u3056\u307e\u306a\u72b6\u6cc1\u3067\u306e\u5fdc\u7528\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-38\">\u57fa\u672c\u7684\u306a\u5f15\u6570\u306e\u5b58\u5728\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u5f15\u6570\u30c1\u30a7\u30c3\u30af\nfunction processUser($user) {\n    \/\/ \u5f15\u6570\u304cnull\u3067\u306a\u3044\u3053\u3068\u3092\u78ba\u8a8d\n    if (is_null($user)) {\n        throw new InvalidArgumentException('\u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u304c\u63d0\u4f9b\u3055\u308c\u3066\u3044\u307e\u305b\u3093');\n    }\n    \n    \/\/ \u4ee5\u964d\u306e\u51e6\u7406\n    echo \"\u30e6\u30fc\u30b6\u30fc\u540d: {$user-&gt;name}\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-39\">\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\u3059\u308b\u30b1\u30fc\u30b9<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u6301\u3064\u5f15\u6570\u3067\u306e\u4f7f\u7528\u4f8b\nfunction formatDate($date = null, $format = 'Y-m-d') {\n    \/\/ \u65e5\u4ed8\u304cnull\u306e\u5834\u5408\u306f\u73fe\u5728\u65e5\u6642\u3092\u4f7f\u7528\n    if (is_null($date)) {\n        $date = new DateTime();\n    } else if (is_string($date)) {\n        \/\/ \u6587\u5b57\u5217\u306e\u5834\u5408\u306fDateTime\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5909\u63db\n        $date = new DateTime($date);\n    }\n    \n    return $date-&gt;format($format);\n}\n\n\/\/ \u4f7f\u7528\u4f8b\necho formatDate();            \/\/ \u73fe\u5728\u306e\u65e5\u4ed8\uff08\u4f8b: 2023-05-15\uff09\necho formatDate('2023-01-01'); \/\/ 2023-01-01\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-40\">\u8907\u6570\u5f15\u6570\u306e\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u8907\u6570\u306e\u5f15\u6570\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u4f8b\nfunction sendNotification($user, $message, $channel = null) {\n    \/\/ \u5fc5\u9808\u5f15\u6570\u306e\u30c1\u30a7\u30c3\u30af\n    if (is_null($user) || is_null($message)) {\n        throw new InvalidArgumentException('\u30e6\u30fc\u30b6\u30fc\u3068\u30e1\u30c3\u30bb\u30fc\u30b8\u306f\u5fc5\u9808\u3067\u3059');\n    }\n    \n    \/\/ \u30aa\u30d7\u30b7\u30e7\u30f3\u5f15\u6570\u306e\u30c1\u30a7\u30c3\u30af\u3068\u51e6\u7406\u5206\u5c90\n    if (is_null($channel)) {\n        \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u30c1\u30e3\u30f3\u30cd\u30eb\u3092\u4f7f\u7528\n        $channel = getUserPreferredChannel($user);\n    }\n    \n    \/\/ \u901a\u77e5\u9001\u4fe1\u51e6\u7406\n    return deliverMessage($user, $message, $channel);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-41\">\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\uff08PHP 7\u4ee5\u964d\uff09<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7\u4ee5\u964d\u306eNull\u8a31\u5bb9\u578b\u3092\u4f7f\u7528\u3057\u305f\u4f8b\nfunction calculateTax(?float $amount, ?float $taxRate = null): float {\n    \/\/ \u91d1\u984d\u304cnull\u306e\u5834\u5408\u306f\u30a8\u30e9\u30fc\n    if (is_null($amount)) {\n        throw new InvalidArgumentException('\u91d1\u984d\u306f\u5fc5\u9808\u3067\u3059');\n    }\n    \n    \/\/ \u7a0e\u7387\u304cnull\u306e\u5834\u5408\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u7a0e\u7387\u3092\u4f7f\u7528\n    if (is_null($taxRate)) {\n        $taxRate = getDefaultTaxRate();\n    }\n    \n    return $amount * ($taxRate \/ 100);\n}\n\n\/\/ \u4f7f\u7528\u4f8b\necho calculateTax(1000, 10);    \/\/ 100.0\necho calculateTax(1000, null);  \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u7a0e\u7387\u3092\u4f7f\u7528\necho calculateTax(null, 10);    \/\/ \u4f8b\u5916\u304c\u30b9\u30ed\u30fc\u3055\u308c\u308b\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-42\">\u53ef\u5909\u9577\u5f15\u6570\u306e\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u53ef\u5909\u9577\u5f15\u6570\uff08...\uff09\u3092\u4f7f\u7528\u3057\u305f\u4f8b\nfunction mergeConfigurations(?array $defaultConfig, ...$userConfigs) {\n    \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u8a2d\u5b9a\u304cnull\u306e\u5834\u5408\u306f\u7a7a\u914d\u5217\u3092\u4f7f\u7528\n    $result = is_null($defaultConfig) ? [] : $defaultConfig;\n    \n    \/\/ \u30e6\u30fc\u30b6\u30fc\u8a2d\u5b9a\u3092\u9806\u306b\u30de\u30fc\u30b8\n    foreach ($userConfigs as $config) {\n        \/\/ null\u3067\u306a\u3044\u8a2d\u5b9a\u306e\u307f\u3092\u30de\u30fc\u30b8\n        if (!is_null($config)) {\n            $result = array_merge($result, $config);\n        }\n    }\n    \n    return $result;\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$merged = mergeConfigurations(\n    ['debug' =&gt; false, 'cache' =&gt; true],\n    ['debug' =&gt; true],\n    null,  \/\/ \u3053\u306e\u5f15\u6570\u306f\u7121\u8996\u3055\u308c\u308b\n    ['timeout' =&gt; 30]\n);\n<\/pre>\n\n\n\n<p><code>is_null()<\/code>\u3092\u4f7f\u3063\u305f\u5f15\u6570\u30c1\u30a7\u30c3\u30af\u306f\u3001\u95a2\u6570\u306e\u9811\u5065\u6027\u3092\u9ad8\u3081\u3001\u4e88\u671f\u305b\u306c\u30a8\u30e9\u30fc\u3084\u30d0\u30b0\u3092\u9632\u3050\u306e\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002\u7279\u306bPHP 7\u4ee5\u964d\u306e\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\u3068null\u8a31\u5bb9\u578b\uff08?\u578b\uff09\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u660e\u78ba\u3067\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u4f5c\u6210\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-43\">\u914d\u5217\u8981\u7d20\u306enull\u30c1\u30a7\u30c3\u30af\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p>\u914d\u5217\u64cd\u4f5c\u306f PHP \u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u4e2d\u5fc3\u7684\u306a\u90e8\u5206\u3067\u3042\u308a\u3001\u914d\u5217\u8981\u7d20\u306e NULL \u5024\u3092\u9069\u5207\u306b\u51e6\u7406\u3059\u308b\u3053\u3068\u306f\u91cd\u8981\u3067\u3059\u3002\u3053\u3053\u3067\u306f\u3001<code>is_null()<\/code> \u95a2\u6570\u3092\u4f7f\u3063\u305f\u914d\u5217\u8981\u7d20\u306e\u52b9\u679c\u7684\u306a\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-44\">\u914d\u5217\u8981\u7d20\u306e\u5b58\u5728\u3068NULL\u5024\u3092\u533a\u5225\u3059\u308b<\/h4>\n\n\n\n<p>\u914d\u5217\u306b\u304a\u3044\u3066\u306f\u300c\u30ad\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\u300d\u72b6\u614b\u3068\u300c\u30ad\u30fc\u306f\u5b58\u5728\u3059\u308b\u304c\u5024\u304c NULL\u300d\u3068\u3044\u3046\u72b6\u614b\u3092\u533a\u5225\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u914d\u5217\u8981\u7d20\u306e\u5b58\u5728\u3068NULL\u5024\u306e\u533a\u5225\n$user = [\n    'name' =&gt; 'John',\n    'email' =&gt; 'john@example.com',\n    'phone' =&gt; null  \/\/ \u660e\u793a\u7684\u306bNULL\n];\n\n\/\/ \u30ad\u30fc\u306e\u5b58\u5728\u78ba\u8a8d\u3068NULL\u5024\u306e\u78ba\u8a8d\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\nif (!array_key_exists('phone', $user)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u5b58\u5728\u3057\u307e\u305b\u3093\";\n} else if (is_null($user['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u96fb\u8a71\u756a\u53f7: {$user['phone']}\";\n}\n\n\/\/ \u4e0a\u8a18\u306e\u4f8b\u3067\u306f \"\u96fb\u8a71\u756a\u53f7\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\" \u3068\u51fa\u529b\u3055\u308c\u308b\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-45\">\u591a\u6b21\u5143\u914d\u5217\u306e\u8981\u7d20\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u591a\u6b21\u5143\u914d\u5217\u306eNULL\u30c1\u30a7\u30c3\u30af\n$data = [\n    'user' =&gt; [\n        'profile' =&gt; [\n            'address' =&gt; null\n        ]\n    ]\n];\n\n\/\/ \u5b89\u5168\u306b\u591a\u6b21\u5143\u914d\u5217\u306e\u8981\u7d20\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\nif (isset($data['user']['profile']) &amp;&amp; !is_null($data['user']['profile']['address'])) {\n    echo \"\u4f4f\u6240: {$data['user']['profile']['address']}\";\n} else {\n    echo \"\u4f4f\u6240\u60c5\u5831\u304c\u3042\u308a\u307e\u305b\u3093\";\n}\n\n\/\/ PHP 7.4\u4ee5\u964d\u3067\u306fNull\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u4f7f\u7528\u3057\u3066\u7c21\u6f54\u306b\u66f8\u3051\u308b\n$address = $data['user']['profile']['address'] ?? null;\nif (!is_null($address)) {\n    echo \"\u4f4f\u6240: {$address}\";\n}\n\n\/\/ PHP 8.0\u4ee5\u964d\u3067\u306fNullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\u3082\u4f7f\u7528\u53ef\u80fd\uff08\u5f8c\u8ff0\uff09\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-46\">\u914d\u5217\u306e\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u3067NULL\u5024\u3092\u9664\u5916\u3059\u308b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ NULL\u5024\u3092\u542b\u3080\u914d\u5217\n$values = [1, null, 3, null, 5];\n\n\/\/ NULL\u5024\u3092\u9664\u5916\u3057\u305f\u3044\u5834\u5408\n$filteredValues = array_filter($values, function($value) {\n    return !is_null($value);\n});\n\n\/\/ PHP 7.4\u4ee5\u964d\u3067\u306f\u77ed\u3044\u69cb\u6587\u3082\u53ef\u80fd\n$filteredValues = array_filter($values, fn($value) =&gt; !is_null($value));\n\nprint_r($filteredValues); \/\/ [0 =&gt; 1, 2 =&gt; 3, 4 =&gt; 5]\n\n\/\/ \u30ad\u30fc\u3092\u4fdd\u6301\u3057\u305f\u307e\u307e\u9023\u7d9a\u7684\u306a\u914d\u5217\u306b\u3057\u305f\u3044\u5834\u5408\n$filteredValues = array_values($filteredValues); \nprint_r($filteredValues); \/\/ [0 =&gt; 1, 1 =&gt; 3, 2 =&gt; 5]\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-47\">\u914d\u5217\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u3067NULL\u5024\u3092\u51e6\u7406\u3059\u308b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u914d\u5217\u5185\u306eNULL\u5024\u3092\u5909\u63db\u3059\u308b\n$data = ['apple', null, 'banana', null, 'orange'];\n\n\/\/ NULL\u5024\u3092\u300c\u4e0d\u660e\u300d\u306b\u7f6e\u304d\u63db\u3048\u308b\n$processed = array_map(function($item) {\n    return is_null($item) ? '\u4e0d\u660e' : $item;\n}, $data);\n\nprint_r($processed); \/\/ ['apple', '\u4e0d\u660e', 'banana', '\u4e0d\u660e', 'orange']\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-48\">\u95a2\u9023\u914d\u5217\u306e\u30ad\u30fc\u30fb\u5024\u30da\u30a2\u306e\u51e6\u7406<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u95a2\u9023\u914d\u5217\u306eNULL\u5024\u306e\u51e6\u7406\n$settings = [\n    'debug' =&gt; true,\n    'cache' =&gt; null,\n    'timeout' =&gt; 30,\n    'retry' =&gt; null\n];\n\n\/\/ NULL\u5024\u3092\u6301\u3064\u30ad\u30fc\u3092\u62bd\u51fa\n$nullKeys = array_keys(array_filter($settings, 'is_null'));\necho \"\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u306a\u3044\u30aa\u30d7\u30b7\u30e7\u30f3: \" . implode(', ', $nullKeys); \/\/ cache, retry\n\n\/\/ NULL\u5024\u3092\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3067\u7f6e\u304d\u63db\u3048\u308b\n$defaults = [\n    'cache' =&gt; false,\n    'retry' =&gt; 3,\n    'log' =&gt; true\n];\n\n\/\/ NULL\u306e\u5834\u5408\u306e\u307f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\uff08PHP 7+\uff09\n$mergedSettings = array_map(function($value) use ($defaults) {\n    $key = key($defaults);\n    next($defaults);\n    return is_null($value) ? ($defaults[$key] ?? $value) : $value;\n}, $settings);\n<\/pre>\n\n\n\n<p>\u914d\u5217\u8981\u7d20\u306e NULL \u30c1\u30a7\u30c3\u30af\u306f\u3001\u30c7\u30fc\u30bf\u51e6\u7406\u306b\u304a\u3044\u3066\u975e\u5e38\u306b\u91cd\u8981\u3067\u3059\u3002\u7279\u306b API \u30ec\u30b9\u30dd\u30f3\u30b9\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u53d6\u5f97\u7d50\u679c\u306a\u3069\u3001\u5916\u90e8\u30c7\u30fc\u30bf\u3092\u6271\u3046\u5834\u5408\u306b\u306f\u3001NULL \u5024\u3092\u9069\u5207\u306b\u51e6\u7406\u3059\u308b\u3053\u3068\u304c\u30a8\u30e9\u30fc\u9632\u6b62\u306b\u3064\u306a\u304c\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-49\">PHP 7\/8\u6642\u4ee3\u306eNULL\u5224\u5b9a\u3068\u6700\u65b0\u30c6\u30af\u30cb\u30c3\u30af<\/h2>\n\n\n\n<p>PHP\u8a00\u8a9e\u306f\u7d99\u7d9a\u7684\u306b\u9032\u5316\u3057\u3066\u304a\u308a\u3001PHP 7\u304a\u3088\u30738\u3067\u306f\u3001NULL\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u65b0\u6a5f\u80fd\u304c\u591a\u6570\u5c0e\u5165\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u308c\u3089\u306e\u65b0\u6a5f\u80fd\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u3092\u3088\u308a\u7c21\u6f54\u306b\u3001\u305d\u3057\u3066\u5b89\u5168\u306b\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u30e2\u30c0\u30f3PHP\u306b\u304a\u3051\u308bNULL\u5024\u306e\u53d6\u308a\u6271\u3044\u306b\u95a2\u3059\u308b\u6700\u65b0\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-50\">Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u4f7f\u3063\u305f\u7c21\u6f54\u306a\u8a18\u8ff0\u6cd5<\/h3>\n\n\n\n<p>PHP 7.0\u3067\u5c0e\u5165\u3055\u308c\u305f\u300cNull\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u300d\u306f\u3001NULL\u5024\u306e\u5224\u5b9a\u3068\u4ee3\u66ff\u5024\u306e\u8a2d\u5b9a\u3092\u7c21\u6f54\u306b\u884c\u3046\u305f\u3081\u306e\u6f14\u7b97\u5b50\u3067\u3059\u3002\u5f93\u6765\u306e\u6761\u4ef6\u5f0f\u3084\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u305f\u30b3\u30fc\u30c9\u3092\u5927\u5e45\u306b\u7c21\u7565\u5316\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-51\">\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5f93\u6765\u306e\u66f8\u304d\u65b9\n$username = isset($user['name']) ? $user['name'] : '\u30b2\u30b9\u30c8';\n\n\/\/ Null\u5408\u4f53\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u305f\u66f8\u304d\u65b9\n$username = $user['name'] ?? '\u30b2\u30b9\u30c8';\n<\/pre>\n\n\n\n<p>Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u306f\u3001\u5de6\u8fba\u304c<code>null<\/code>\u307e\u305f\u306f\u672a\u5b9a\u7fa9\uff08\u5b58\u5728\u3057\u306a\u3044\u5909\u6570\u30fb\u914d\u5217\u30ad\u30fc\uff09\u306e\u5834\u5408\u306b\u53f3\u8fba\u306e\u5024\u3092\u8fd4\u3057\u307e\u3059\u3002\u5de6\u8fba\u304c<code>null<\/code>\u4ee5\u5916\uff080\u3084\u7a7a\u6587\u5b57\u5217\u3001false\u306a\u3069\u3082\u542b\u3080\uff09\u3067\u3042\u308c\u3070\u5de6\u8fba\u306e\u5024\u3092\u305d\u306e\u307e\u307e\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-52\">\u5f93\u6765\u306eisset()\u3068\u306e\u9055\u3044<\/h4>\n\n\n\n<p><code>isset()<\/code>\u3068<code>??<\/code>\u306e\u5927\u304d\u306a\u9055\u3044\u306f\u3001\u300c\u7a7a\u300d\u3068\u5224\u5b9a\u3055\u308c\u308b\u5024\u306e\u6271\u3044\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5909\u6570\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u304c\u300c\u7a7a\u300d\u306e\u5024\u306e\u4f8b\n$zero = 0;\n$emptyString = '';\n$false = false;\n\n\/\/ isset()\u306f\u3053\u308c\u3089\u306e\u5024\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u3053\u3068\u3092\u5224\u5b9a\u3059\u308b\nvar_dump(isset($zero));       \/\/ bool(true)\nvar_dump(isset($emptyString)); \/\/ bool(true)\nvar_dump(isset($false));      \/\/ bool(true)\n\n\/\/ ??\u6f14\u7b97\u5b50\u3067\u3082\u540c\u69d8\u306b\u5de6\u8fba\u306e\u5024\u304c\u8fd4\u3055\u308c\u308b\nvar_dump($zero ?? '\u30c7\u30d5\u30a9\u30eb\u30c8');       \/\/ int(0)\nvar_dump($emptyString ?? '\u30c7\u30d5\u30a9\u30eb\u30c8'); \/\/ string(0) \"\"\nvar_dump($false ?? '\u30c7\u30d5\u30a9\u30eb\u30c8');      \/\/ bool(false)\n\n\/\/ \u5bfe\u7167\u7684\u306b\u3001empty()\u306f\u3053\u308c\u3089\u3092\u300c\u7a7a\u300d\u3068\u5224\u5b9a\u3059\u308b\nvar_dump(empty($zero));       \/\/ bool(true)\nvar_dump(empty($emptyString)); \/\/ bool(true)\nvar_dump(empty($false));      \/\/ bool(false)\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-53\">\u9023\u7d9a\u3057\u305fNull\u5408\u4f53\u6f14\u7b97\u5b50<\/h4>\n\n\n\n<p>\u8907\u6570\u306e\u5019\u88dc\u304b\u3089\u6700\u521d\u306enull\u4ee5\u5916\u306e\u5024\u3092\u9078\u3076\u3053\u3068\u3082\u53ef\u80fd\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u512a\u5148\u9806\u4f4d\u306b\u5f93\u3063\u3066\u6700\u521d\u306enull\u3067\u306a\u3044\u5024\u3092\u4f7f\u7528\n$displayName = $user-&gt;nickname ?? $user-&gt;username ?? $user-&gt;email ?? '\u30b2\u30b9\u30c8';\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-54\">\u5909\u6570\u4ee3\u5165\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u8a2d\u5b9a\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306e\u307f\u5909\u6570\u306b\u4ee3\u5165\nfunction loadConfiguration($configPath) {\n    $config = [];\n    \n    \/\/ \u30d5\u30a1\u30a4\u30eb\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306e\u307f\u8aad\u307f\u8fbc\u307f\n    $fileContent = @file_get_contents($configPath) ?? null;\n    if (!is_null($fileContent)) {\n        $config = json_decode($fileContent, true);\n    }\n    \n    \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u8a2d\u5b9a\u3068\u30de\u30fc\u30b8\n    return array_merge(getDefaultConfig(), $config);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-55\">\u914d\u5217\u64cd\u4f5c\u3067\u306e\u6d3b\u7528<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b89\u5168\u306a\u914d\u5217\u30a2\u30af\u30bb\u30b9\nfunction getUserSetting($userId, $key) {\n    $settings = fetchUserSettings($userId);\n    \n    \/\/ \u591a\u6b21\u5143\u914d\u5217\u306e\u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\n    return $settings[$key] ?? \n           $settings['defaults'][$key] ?? \n           getGlobalDefault($key);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-56\">is_null()\u3068\u306e\u4f7f\u3044\u5206\u3051<\/h4>\n\n\n\n<p>Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u306f<code>isset()<\/code>\u306e\u4ee3\u66ff\u3068\u3057\u3066\u4f7f\u3044\u3084\u3059\u3044\u3067\u3059\u304c\u3001\u660e\u793a\u7684\u306b\u5024\u304c<code>null<\/code>\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3059\u308b\u5834\u5408\u306b\u306f<code>is_null()<\/code>\u95a2\u6570\u3084<code>=== null<\/code>\u6bd4\u8f03\u3082\u5f15\u304d\u7d9a\u304d\u91cd\u8981\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Null\u5408\u4f53\u6f14\u7b97\u5b50\u3067\u306f\u672a\u5b9a\u7fa9\u5909\u6570\u3068null\u3092\u533a\u5225\u3057\u306a\u3044\n$var = null;\n$result = $var ?? '\u30c7\u30d5\u30a9\u30eb\u30c8'; \/\/ '\u30c7\u30d5\u30a9\u30eb\u30c8'\u304c\u4f7f\u7528\u3055\u308c\u308b\n\n\/\/ \u660e\u793a\u7684\u306bnull\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3059\u308b\u5834\u5408\nif (is_null($var)) {\n    \/\/ \u5909\u6570\u306e\u5024\u304c\u53b3\u5bc6\u306bnull\u306e\u5834\u5408\u306e\u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>Null\u5408\u4f53\u6f14\u7b97\u5b50\u306f\u3001\u7279\u306b\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u8a2d\u5b9a\u3084\u5b89\u5168\u306a\u914d\u5217\u8981\u7d20\u30a2\u30af\u30bb\u30b9\u306a\u3069\u3001\u65e5\u5e38\u7684\u306a\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b7\u30fc\u30f3\u3067\u975e\u5e38\u306b\u6709\u7528\u3067\u3059\u3002<code>is_null()<\/code>\u3084<code>isset()<\/code>\u3068\u6bd4\u8f03\u3057\u3066\u3001\u3088\u308a\u7c21\u6f54\u3067\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-57\">Nullsafe\u6f14\u7b97\u5b50\u3067\u306enull\u30c1\u30a7\u30c3\u30af\u52b9\u7387\u5316<\/h3>\n\n\n\n<p>PHP 8.0\u3067\u5c0e\u5165\u3055\u308c\u305f\u300cNullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\u300d\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30c1\u30a7\u30fc\u30f3\u3067\u306eNull\u5b89\u5168\u6027\u3092\u5927\u5e45\u306b\u5411\u4e0a\u3055\u305b\u308b\u753b\u671f\u7684\u306a\u6a5f\u80fd\u3067\u3059\u3002\u3053\u306e\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u6df1\u304f\u30cd\u30b9\u30c8\u3057\u305f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3084\u30e1\u30bd\u30c3\u30c9\u547c\u3073\u51fa\u3057\u3092\u5b89\u5168\u304b\u3064\u7c21\u6f54\u306b\u8a18\u8ff0\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-58\">\u5f93\u6765\u306enull\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\u306e\u554f\u984c\u70b9<\/h4>\n\n\n\n<p>PHP 8.0\u4ee5\u524d\u3067\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30c1\u30a7\u30fc\u30f3\u306e\u5404\u6bb5\u968e\u3067null\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u5fc5\u8981\u304c\u3042\u308a\u3001\u975e\u5e38\u306b\u5197\u9577\u306a\u30b3\u30fc\u30c9\u306b\u306a\u308a\u304c\u3061\u3067\u3057\u305f\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 8.0\u4ee5\u524d\u306enull\u30c1\u30a7\u30c3\u30af\n$country = null;\nif ($user !== null) {\n    $address = $user-&gt;getAddress();\n    if ($address !== null) {\n        $country = $address-&gt;getCountry();\n    }\n}\n<\/pre>\n\n\n\n<p>\u307e\u305f\u306f\u3001\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u3066\u3082\u8907\u96d1\u306b\u306a\u308a\u304c\u3061\u3067\u3057\u305f\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u3063\u305f\u4f8b\n$country = $user !== null ? ($user-&gt;getAddress() !== null ? $user-&gt;getAddress()-&gt;getCountry() : null) : null;\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-59\">Nullsafe\u6f14\u7b97\u5b50\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/h4>\n\n\n\n<p>Nullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\u3092\u4f7f\u3046\u3068\u3001\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u304c\u9a5a\u304f\u307b\u3069\u7c21\u6f54\u306b\u306a\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 8.0\u4ee5\u964d\u306eNullsafe\u6f14\u7b97\u5b50\n$country = $user?-&gt;getAddress()?-&gt;getCountry();\n<\/pre>\n\n\n\n<p>\u3053\u308c\u306f\u300c$user\u304cnull\u3067\u306a\u3051\u308c\u3070getAddress()\u3092\u547c\u3073\u51fa\u3057\u3001\u305d\u306e\u7d50\u679c\u304cnull\u3067\u306a\u3051\u308c\u3070getCountry()\u3092\u547c\u3073\u51fa\u3059\u3002\u3044\u305a\u308c\u304b\u306e\u6bb5\u968e\u3067null\u304c\u767a\u751f\u3057\u305f\u3089\u3001\u6700\u7d42\u7d50\u679c\u3082null\u306b\u306a\u308b\u300d\u3068\u3044\u3046\u52d5\u4f5c\u3092\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-60\">Nullsafe\u6f14\u7b97\u5b50\u3068\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3<\/h4>\n\n\n\n<p>\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u3082\u540c\u69d8\u306b\u4f7f\u7528\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u306e\u4f7f\u7528\u4f8b\n$result = $repository?-&gt;findById($id)?-&gt;process()?-&gt;toArray();\n<\/pre>\n\n\n\n<p>\u5404\u6bb5\u968e\u3067null\u30c1\u30a7\u30c3\u30af\u304c\u884c\u308f\u308c\u3001\u3069\u306e\u6bb5\u968e\u3067\u3082null\u304c\u767a\u751f\u3059\u308c\u3070\u3001\u4ee5\u964d\u306e\u51e6\u7406\u306f\u30b9\u30ad\u30c3\u30d7\u3055\u308c\u6700\u7d42\u7684\u306bnull\u304c\u8fd4\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-61\">\u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9\u3067\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9\u306b\u3082\u4f7f\u7528\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9\u306e\u4f8b\n$name = $user?-&gt;profile?-&gt;firstName;\n\n\/\/ \u52d5\u7684\u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9\u3067\u3082\u6a5f\u80fd\u3059\u308b\n$fieldName = 'firstName';\n$name = $user?-&gt;profile?-&gt;$fieldName;\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-62\">\u914d\u5217\u30a2\u30af\u30bb\u30b9\u3068\u306e\u4f75\u7528<\/h4>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u914d\u5217\u306e\u6df7\u5408\u30a2\u30af\u30bb\u30b9\u3067\u3082\u4f7f\u7528\u53ef\u80fd\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u914d\u5217\u30a2\u30af\u30bb\u30b9\u306e\u7d44\u307f\u5408\u308f\u305b\n$value = $user?-&gt;preferences['notifications']['email'] ?? '\u30c7\u30d5\u30a9\u30eb\u30c8\u5024';\n\n\/\/ \u3088\u308a\u5b89\u5168\u306a\u66f8\u304d\u65b9\n$value = $user?-&gt;preferences['notifications']['email'] ?? $user?-&gt;preferences['defaults']['email'] ?? '\u30c7\u30d5\u30a9\u30eb\u30c8\u5024';\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-63\">\u30e1\u30bd\u30c3\u30c9\u623b\u308a\u5024\u306enull\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<p>\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u306b\u5bfe\u3057\u3066\u3082\u5373\u5ea7\u306b\u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\u304c\u53ef\u80fd\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e1\u30bd\u30c3\u30c9\u623b\u308a\u5024\u306e\u30c1\u30a7\u30fc\u30f3\n$price = $order?-&gt;getProduct()?-&gt;getPrice();\n\n\/\/ \u5f15\u6570\u3092\u6301\u3064\u30e1\u30bd\u30c3\u30c9\u3067\u3082\u554f\u984c\u306a\u304f\u52d5\u4f5c\n$price = $order?-&gt;getProductById(123)?-&gt;calculateDiscountedPrice(0.9);\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-64\">Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<p>Nullsafe\u6f14\u7b97\u5b50\u306fNull\u5408\u4f53\u6f14\u7b97\u5b50\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u67d4\u8edf\u306a\u6761\u4ef6\u5206\u5c90\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Nullsafe\u6f14\u7b97\u5b50\u3068Null\u5408\u4f53\u6f14\u7b97\u5b50\u306e\u7d44\u307f\u5408\u308f\u305b\n$country = $user?-&gt;getAddress()?-&gt;getCountry() ?? '\u672a\u8a2d\u5b9a';\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-65\">is_null()\u95a2\u6570\u3068\u306e\u4f7f\u3044\u5206\u3051<\/h4>\n\n\n\n<p>Nullsafe\u6f14\u7b97\u5b50\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30c1\u30a7\u30fc\u30f3\u306enull\u30c1\u30a7\u30c3\u30af\u3092\u52b9\u7387\u5316\u3057\u307e\u3059\u304c\u3001\u5358\u4e00\u306e\u5909\u6570\u304c\u660e\u793a\u7684\u306bnull\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u5834\u5408\u306b\u306f\u3001\u4f9d\u7136\u3068\u3057\u3066is_null()\u95a2\u6570\u3084=== null\u6bd4\u8f03\u304c\u6709\u7528\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Nullsafe\u6f14\u7b97\u5b50\u3067\u306f\u9069\u3055\u306a\u3044\u30b1\u30fc\u30b9\nif (is_null($config)) {\n    $config = loadDefaultConfig();\n}\n\n\/\/ \u3053\u3061\u3089\u306fNullsafe\u6f14\u7b97\u5b50\u304c\u9069\u3057\u3066\u3044\u308b\n$setting = $config?-&gt;getSection('database')?-&gt;getConnection('primary');\n<\/pre>\n\n\n\n<p>Nullsafe\u6f14\u7b97\u5b50\u306f\u3001\u7279\u306b\u8907\u96d1\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u69cb\u9020\u3092\u6271\u3046\u969b\u306b\u3001\u30b3\u30fc\u30c9\u3092\u5927\u5e45\u306b\u7c21\u7565\u5316\u3057\u53ef\u8aad\u6027\u3092\u5411\u4e0a\u3055\u305b\u307e\u3059\u3002\u30e2\u30c0\u30f3\u306aPHP\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u3067\u306f\u3001\u3053\u306e\u6f14\u7b97\u5b50\u3092\u7a4d\u6975\u7684\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-66\">Null\u578b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3078\u306e\u9032\u5316\u3068\u30e2\u30c0\u30f3\u624b\u6cd5<\/h3>\n\n\n\n<p>PHP 7.1\u4ee5\u964d\u3067\u306f\u3001\u578b\u30b7\u30b9\u30c6\u30e0\u306e\u5f37\u5316\u306b\u3088\u308a\u3001\u3088\u308a\u660e\u793a\u7684\u3067\u5b89\u5168\u306anull\u5024\u306e\u53d6\u308a\u6271\u3044\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u3053\u3053\u3067\u306f\u3001\u30e2\u30c0\u30f3PHP\u3067null\u578b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u305f\u3081\u306e\u624b\u6cd5\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-67\">Null\u8a31\u5bb9\u578b\uff08?\u578b\uff09\u306e\u5c0e\u5165<\/h4>\n\n\n\n<p>PHP 7.1\u3067\u5c0e\u5165\u3055\u308c\u305fNull\u8a31\u5bb9\u578b\uff08Nullable Type\uff09\u306f\u3001\u578b\u5ba3\u8a00\u306bnull\u3092\u8a31\u5bb9\u3059\u308b\u3053\u3068\u3092\u660e\u793a\u3059\u308b\u305f\u3081\u306e\u6a5f\u80fd\u3067\u3059\u3002\u578b\u306e\u524d\u306b<code>?<\/code>\u3092\u4ed8\u3051\u308b\u3053\u3068\u3067\u3001\u305d\u306e\u5909\u6570\u3084\u5f15\u6570\u3001\u623b\u308a\u5024\u304cnull\u3092\u8a31\u5bb9\u3059\u308b\u3053\u3068\u3092\u793a\u305b\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Null\u8a31\u5bb9\u578b\u306e\u57fa\u672c\nfunction process(?string $name): ?string {\n    if (is_null($name)) {\n        return null;\n    }\n    \n    return strtoupper($name);\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$result1 = process(\"hello\"); \/\/ \"HELLO\"\n$result2 = process(null);    \/\/ null\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-68\">Union Types\u3067\u306enull\u578b\uff08PHP 8.0\u4ee5\u964d\uff09<\/h4>\n\n\n\n<p>PHP 8.0\u3067\u306f\u3001\u8907\u6570\u306e\u578b\u3092\u6307\u5b9a\u3067\u304d\u308bUnion Types\u304c\u5c0e\u5165\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u308c\u306b\u3088\u308a\u3001null\u8a31\u5bb9\u578b\u3092\u3088\u308a\u660e\u793a\u7684\u306b\u8a18\u8ff0\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 8.0\u306eUnion Types\nfunction getData(string|int $id): array|null {\n    \/\/ string\u578b\u307e\u305f\u306fint\u578b\u306eid\u3092\u53d7\u3051\u53d6\u308a\u3001\n    \/\/ array\u578b\u307e\u305f\u306fnull\u3092\u8fd4\u3059\u95a2\u6570\n    \n    $data = fetchFromDatabase($id);\n    return $data ?: null;\n}\n\n\/\/ PHP 8.0\u4ee5\u524d\u306eNull\u8a31\u5bb9\u578b\u3068\u540c\u7b49\nfunction getUser(?int $id): ?array {\n    \/\/ ...\n}\n\n\/\/ PHP 8.0\u3067\u306eUnion Types\u3092\u4f7f\u3063\u305fNull\u8a31\u5bb9\u578b\nfunction getUser(int|null $id): array|null {\n    \/\/ ...\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-69\">\u30d7\u30ed\u30d1\u30c6\u30a3\u306eNull\u8a31\u5bb9\u578b<\/h4>\n\n\n\n<p>\u30af\u30e9\u30b9\u30d7\u30ed\u30d1\u30c6\u30a3\u3067\u3082Null\u8a31\u5bb9\u578b\u3092\u4f7f\u7528\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    \/\/ null\u8a31\u5bb9\u30d7\u30ed\u30d1\u30c6\u30a3\n    public ?string $name;\n    public ?string $email;\n    \n    \/\/ \u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u30d7\u30ed\u30d1\u30c6\u30a3\u30d7\u30ed\u30e2\u30fc\u30b7\u30e7\u30f3\uff08PHP 8.0\u4ee5\u964d\uff09\n    public function __construct(\n        public string $username,\n        public ?string $firstName = null,\n        public ?string $lastName = null\n    ) {}\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$user = new User('john_doe');\n$user-&gt;email = 'john@example.com';\n$user-&gt;name = null; \/\/ \u6709\u52b9\uff08Null\u8a31\u5bb9\u578b\u306e\u305f\u3081\uff09\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-70\">Typed Properties\u3068null\u306e\u521d\u671f\u5316\uff08PHP 7.4\u4ee5\u964d\uff09<\/h4>\n\n\n\n<p>PHP 7.4\u3067\u5c0e\u5165\u3055\u308c\u305fTyped Properties\u3067\u306f\u3001\u578b\u4ed8\u304d\u30d7\u30ed\u30d1\u30c6\u30a3\u306e\u521d\u671f\u5316\u304c\u91cd\u8981\u306b\u306a\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Product {\n    \/\/ \u578b\u4ed8\u304d\u30d7\u30ed\u30d1\u30c6\u30a3\uff08\u521d\u671f\u5316\u304c\u5fc5\u8981\uff09\n    public string $name;\n    public float $price;\n    \n    \/\/ null\u8a31\u5bb9\u30d7\u30ed\u30d1\u30c6\u30a3\uff08\u521d\u671f\u5316\u304c\u4e0d\u8981\uff09\n    public ?string $description = null;\n    \n    \/\/ \u521d\u671f\u5316\u6e08\u307f\u30d7\u30ed\u30d1\u30c6\u30a3\n    public int $stock = 0;\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$product = new Product();\n$product-&gt;name = '\u30b9\u30de\u30fc\u30c8\u30d5\u30a9\u30f3'; \/\/ OK\n\/\/ $product-&gt;price \u3078\u306e\u30a2\u30af\u30bb\u30b9\uff08\u521d\u671f\u5316\u524d\uff09\u306f\u30a8\u30e9\u30fc\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-71\">Null\u5b89\u5168\u6027\u3092\u9ad8\u3081\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u660e\u793a\u7684\u306aNull\u8a31\u5bb9\u578b\u306e\u4f7f\u7528<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u826f\u3044\u4f8b: \u660e\u793a\u7684\u306anull\u8a31\u5bb9\u578b\nfunction getUserName(?int $userId): ?string {\n    if (is_null($userId)) {\n        return null;\n    }\n    \n    $user = findUser($userId);\n    return $user ? $user-&gt;name : null;\n}\n\n\/\/ \u907f\u3051\u308b\u3079\u304d\u4f8b: \u66d6\u6627\u306a\u578b\nfunction getUserName($userId) {\n    \/\/ \u578b\u306e\u4e0d\u660e\u78ba\u3055\u304c\u5c06\u6765\u7684\u306a\u554f\u984c\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\n}\n<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li><strong>\u521d\u671f\u5024\u306e\u660e\u793a\u7684\u306a\u8a2d\u5b9a<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u826f\u3044\u4f8b: \u660e\u793a\u7684\u306a\u521d\u671f\u5316\nclass Configuration {\n    private ?array $settings = null;\n    \n    public function load(string $path): bool {\n        \/\/ ...\n    }\n}\n\n\/\/ \u907f\u3051\u308b\u3079\u304d\u4f8b: \u6697\u9ed9\u7684\u306a\u521d\u671f\u5316\u3078\u306e\u4f9d\u5b58\nclass Configuration {\n    private ?array $settings; \/\/ \u660e\u793a\u7684\u306b\u521d\u671f\u5316\u3055\u308c\u3066\u3044\u306a\u3044\n}\n<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li><strong>\u65e9\u671f\u30ea\u30bf\u30fc\u30f3\u30d1\u30bf\u30fc\u30f3\u306e\u6d3b\u7528<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u826f\u3044\u4f8b: \u65e9\u671f\u30ea\u30bf\u30fc\u30f3\u3067null\u30b1\u30fc\u30b9\u3092\u51e6\u7406\nfunction processData(?array $data): string {\n    if (is_null($data)) {\n        return 'No data available';\n    }\n    \n    if (empty($data)) {\n        return 'Empty data set';\n    }\n    \n    \/\/ \u4ee5\u964d\u306f$data\u304cnull\u3067\u306a\u3044\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u3066\u3044\u308b\n    return analyzeData($data);\n}\n<\/pre>\n\n\n\n<ol start=\"4\" class=\"wp-block-list\">\n<li><strong>Null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3\u306e\u6d3b\u7528<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3\u306e\u4f8b\ninterface Logger {\n    public function log(string $message): void;\n}\n\nclass FileLogger implements Logger {\n    public function log(string $message): void {\n        \/\/ \u30d5\u30a1\u30a4\u30eb\u306b\u30ed\u30b0\u3092\u66f8\u304d\u8fbc\u3080\n    }\n}\n\nclass NullLogger implements Logger {\n    public function log(string $message): void {\n        \/\/ \u4f55\u3082\u3057\u306a\u3044\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nfunction processOrder(Order $order, ?Logger $logger = null) {\n    \/\/ Null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f7f\u7528\u3057\u3066null\u30c1\u30a7\u30c3\u30af\u3092\u56de\u907f\n    $logger = $logger ?? new NullLogger();\n    \n    $logger-&gt;log('\u6ce8\u6587\u51e6\u7406\u958b\u59cb');\n    \/\/ \u51e6\u7406...\n    $logger-&gt;log('\u6ce8\u6587\u51e6\u7406\u5b8c\u4e86');\n}\n<\/pre>\n\n\n\n<p>\u30e2\u30c0\u30f3PHP\u3067\u306f\u3001\u578b\u30b7\u30b9\u30c6\u30e0\u306e\u5f37\u5316\u306b\u3088\u308a\u3001Null\u578b\u5b89\u5168\u6027\u3092\u9ad8\u3081\u308b\u305f\u3081\u306e\u69d8\u3005\u306a\u624b\u6bb5\u304c\u63d0\u4f9b\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u3089\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-72\">\u540d\u524d\u7a7a\u9593\u3067\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u547c\u3073\u51fa\u3057\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9<\/h3>\n\n\n\n<p>\u30e2\u30c0\u30f3PHP\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u540d\u524d\u7a7a\u9593\uff08namespace\uff09\u306e\u4f7f\u7528\u304c\u4e00\u822c\u7684\u3067\u3059\u304c\u3001\u540d\u524d\u7a7a\u9593\u5185\u3067\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\uff08<code>is_null()<\/code>\u306a\u3069\uff09\u3092\u547c\u3073\u51fa\u3059\u969b\u306b\u306f\u6ce8\u610f\u70b9\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u540d\u524d\u7a7a\u9593\u74b0\u5883\u3067\u306e<code>is_null()<\/code>\u95a2\u6570\u306e\u52b9\u7387\u7684\u306a\u547c\u3073\u51fa\u3057\u65b9\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u95a2\u3059\u308b\u8003\u616e\u4e8b\u9805\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-73\">\u540d\u524d\u7a7a\u9593\u5185\u3067\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057<\/h4>\n\n\n\n<p>\u540d\u524d\u7a7a\u9593\u3092\u4f7f\u7528\u3057\u305f\u30b3\u30fc\u30c9\u3067\u3001\u5148\u982d\u306b\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\uff08<code>\\<\/code>\uff09\u3092\u4ed8\u3051\u305a\u306b\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u3068\u3001\u6700\u521d\u306b\u73fe\u5728\u306e\u540d\u524d\u7a7a\u9593\u5185\u3067\u95a2\u6570\u3092\u63a2\u305d\u3046\u3068\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">namespace App\\Services;\n\nclass UserService\n{\n    public function processUser($user)\n    {\n        \/\/ \u554f\u984c\u306e\u3042\u308b\u547c\u3073\u51fa\u3057\u65b9\n        if (is_null($user)) {\n            return false;\n        }\n        \n        \/\/ ...\n    }\n}\n<\/pre>\n\n\n\n<p>\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u3067\u306f\u3001PHP\u306f\u6700\u521d\u306b<code>App\\Services\\is_null()<\/code>\u3092\u63a2\u3057\u3001\u898b\u3064\u304b\u3089\u306a\u3051\u308c\u3070\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u306e<code>\\is_null()<\/code>\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u4f59\u5206\u306a\u95a2\u6570\u89e3\u6c7a\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-74\">\u52b9\u7387\u7684\u306a\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u65b9<\/h4>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316\u3059\u308b\u305f\u3081\u306b\u306f\u3001\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u969b\u306b\u5148\u982d\u306b\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4ed8\u3051\u308b\u306e\u304c\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">namespace App\\Services;\n\nclass UserService\n{\n    public function processUser($user)\n    {\n        \/\/ \u52b9\u7387\u7684\u306a\u547c\u3073\u51fa\u3057\u65b9\n        if (\\is_null($user)) {\n            return false;\n        }\n        \n        \/\/ ...\n    }\n}\n<\/pre>\n\n\n\n<p>\u3053\u308c\u306b\u3088\u308a\u3001PHP\u306f\u6700\u521d\u304b\u3089\u6b63\u3057\u3044\u95a2\u6570\uff08\u30b0\u30ed\u30fc\u30d0\u30eb\u540d\u524d\u7a7a\u9593\u306e<code>is_null<\/code>\uff09\u3092\u63a2\u3059\u3053\u3068\u304c\u3067\u304d\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u5411\u4e0a\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-75\">use\u95a2\u6570\u3092\u4f7f\u3063\u305f\u65b9\u6cd5<\/h4>\n\n\n\n<p><code>use function<\/code>\u30c7\u30a3\u30ec\u30af\u30c6\u30a3\u30d6\u3092\u4f7f\u7528\u3057\u3066\u3001\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u3092\u30a4\u30f3\u30dd\u30fc\u30c8\u3059\u308b\u3053\u3068\u3082\u53ef\u80fd\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">namespace App\\Services;\n\n\/\/ \u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u306e\u30a4\u30f3\u30dd\u30fc\u30c8\nuse function is_null;\nuse function array_filter;\nuse function json_encode;\n\nclass DataService\n{\n    public function process($data)\n    {\n        \/\/ \u30a4\u30f3\u30dd\u30fc\u30c8\u3057\u305f\u95a2\u6570\u306f\u76f4\u63a5\u547c\u3073\u51fa\u305b\u308b\n        if (is_null($data)) {\n            return [];\n        }\n        \n        \/\/ \u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u51e6\u7406\n        $filtered = array_filter($data, function($item) {\n            return !is_null($item);\n        });\n        \n        \/\/ JSON\u5f62\u5f0f\u306b\u5909\u63db\n        return json_encode($filtered);\n    }\n}\n<\/pre>\n\n\n\n<p>\u3053\u306e\u65b9\u6cd5\u3082\u52b9\u7387\u7684\u3067\u3059\u304c\u3001\u591a\u6570\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u3092\u4f7f\u7528\u3059\u308b\u5834\u5408\u306f\u5197\u9577\u306b\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-76\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u5f71\u97ff<\/h4>\n\n\n\n<p>\u4e00\u822c\u7684\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u540d\u524d\u7a7a\u9593\u89e3\u6c7a\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u306f\u5c0f\u3055\u3044\u3067\u3059\u304c\u3001\u5927\u898f\u6a21\u306a\u30eb\u30fc\u30d7\u3084\u983b\u7e41\u306a\u95a2\u6570\u547c\u3073\u51fa\u3057\u304c\u3042\u308b\u5834\u5408\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">namespace App\\Services;\n\nclass BenchmarkService\n{\n    public function run()\n    {\n        $startTime = microtime(true);\n        \n        for ($i = 0; $i &lt; 1000000; $i++) {\n            $var = null;\n            is_null($var); \/\/ \u540d\u524d\u7a7a\u9593\u89e3\u6c7a\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u3042\u308a\n        }\n        \n        $endTime = microtime(true);\n        echo \"Without backslash: \" . ($endTime - $startTime) . \" seconds\\n\";\n        \n        $startTime = microtime(true);\n        \n        for ($i = 0; $i &lt; 1000000; $i++) {\n            $var = null;\n            \\is_null($var); \/\/ \u540d\u524d\u7a7a\u9593\u89e3\u6c7a\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u306a\u3057\n        }\n        \n        $endTime = microtime(true);\n        echo \"With backslash: \" . ($endTime - $startTime) . \" seconds\\n\";\n    }\n}\n<\/pre>\n\n\n\n<p>\u5b9f\u969b\u306e\u30d9\u30f3\u30c1\u30de\u30fc\u30af\u3067\u306f\u3001\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4f7f\u7528\u3057\u305f\u65b9\u6cd5\u304c\u6570\u30d1\u30fc\u30bb\u30f3\u30c8\u9ad8\u901f\u306b\u306a\u308b\u3053\u3068\u304c\u591a\u3044\u3067\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-77\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u8003\u616e<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u983b\u7e41\u306b\u547c\u3073\u51fa\u3055\u308c\u308b\u95a2\u6570<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u30eb\u30fc\u30d7\u5185\u3084\u983b\u7e41\u306b\u547c\u3073\u51fa\u3055\u308c\u308b\u95a2\u6570\u3067\u306f\u3001\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4ed8\u3051\u308b\u3053\u3068\u3067\u308f\u305a\u304b\u306a\u6539\u5584\u304c\u7a4d\u307f\u91cd\u306a\u308a\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u8aad\u307f\u3084\u3059\u3055\u3068\u306e\u30d0\u30e9\u30f3\u30b9<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u30b3\u30fc\u30c9\u306e\u8aad\u307f\u3084\u3059\u3055\u3082\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002\u30c1\u30fc\u30e0\u5185\u3067\u4e00\u8cab\u3057\u305f\u898f\u7d04\u3092\u8a2d\u3051\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\u306e\u6d3b\u7528<\/strong>\n<ul class=\"wp-block-list\">\n<li>PHPStan\u3084Psalm\u306a\u3069\u306e\u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\u306f\u3001\u540d\u524d\u7a7a\u9593\u5185\u3067\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u547c\u3073\u51fa\u3057\u306b\u95a2\u3059\u308b\u8b66\u544a\u3092\u8868\u793a\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u30a8\u30f3\u30b8\u30f3\u306e\u6700\u9069\u5316<\/strong>\n<ul class=\"wp-block-list\">\n<li>PHP 7\u4ee5\u964d\u306e\u30a8\u30f3\u30b8\u30f3\u3067\u306f\u3001\u540d\u524d\u7a7a\u9593\u89e3\u6c7a\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u5411\u4e0a\u3057\u3066\u3044\u307e\u3059\u304c\u3001\u305d\u308c\u3067\u3082\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4ed8\u3051\u308b\u65b9\u304c\u308f\u305a\u304b\u306b\u9ad8\u901f\u3067\u3059\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<p>\u30e2\u30c0\u30f3PHP\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u8aad\u307f\u3084\u3059\u3055\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u8003\u616e\u3057\u305f\u4e0a\u3067\u3001\u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u65b9\u3092\u9078\u629e\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u7279\u306b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u91cd\u8981\u306a\u7b87\u6240\u3067\u306f\u3001<code>\\is_null()<\/code>\u306e\u3088\u3046\u306b\u30d0\u30c3\u30af\u30b9\u30e9\u30c3\u30b7\u30e5\u3092\u4ed8\u3051\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-78\">is_null\u95a2\u6570\u4f7f\u7528\u6642\u306e\u3088\u304f\u3042\u308b\u30a8\u30e9\u30fc\u3068\u5bfe\u51e6\u6cd5<\/h2>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306f\u57fa\u672c\u7684\u3067\u4fbf\u5229\u306a\u30c4\u30fc\u30eb\u3067\u3059\u304c\u3001\u4f7f\u3044\u65b9\u3092\u8aa4\u308b\u3068\u30a8\u30e9\u30fc\u3084\u30d0\u30b0\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>is_null()<\/code>\u95a2\u6570\u4f7f\u7528\u6642\u306b\u3088\u304f\u767a\u751f\u3059\u308b\u30a8\u30e9\u30fc\u3068\u305d\u306e\u5bfe\u51e6\u6cd5\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u77e5\u8b58\u3092\u8eab\u306b\u3064\u3051\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-79\">\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u3088\u308b\u8b66\u544a\u30e1\u30c3\u30bb\u30fc\u30b8\u306e\u56de\u907f\u65b9\u6cd5<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u4f7f\u7528\u6642\u306b\u6700\u3082\u3088\u304f\u906d\u9047\u3059\u308b\u30a8\u30e9\u30fc\u306e\u4e00\u3064\u304c\u3001\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308b\u8b66\u544a\u30e1\u30c3\u30bb\u30fc\u30b8\u3067\u3059\u3002PHP \u306f\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066 <code>E_NOTICE<\/code> \u30ec\u30d9\u30eb\u306e\u8b66\u544a\u3092\u767a\u751f\u3055\u305b\u307e\u3059\u3002\u3053\u308c\u3092\u56de\u907f\u3059\u308b\u305f\u3081\u306e\u3044\u304f\u3064\u304b\u306e\u65b9\u6cd5\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-80\">\u554f\u984c\u306e\u4f8b<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u672a\u5b9a\u7fa9\u5909\u6570\u306b\u5bfe\u3059\u308bis_null()\u306e\u4f7f\u7528\nif (is_null($undefinedVar)) {\n    echo \"\u5909\u6570\u306fNULL\u3067\u3059\";\n}\n\/\/ \u51fa\u529b: Warning: Undefined variable $undefinedVar in \/path\/to\/file.php on line X\n<\/pre>\n\n\n\n<p>\u3053\u306e\u8b66\u544a\u306f\u3001\u5909\u6570\u304c\u5b58\u5728\u3057\u306a\u3044\u306b\u3082\u304b\u304b\u308f\u3089\u305a<code>is_null()<\/code>\u95a2\u6570\u304c\u305d\u306e\u5024\u3092\u8a55\u4fa1\u3057\u3088\u3046\u3068\u3057\u3066\u3044\u308b\u305f\u3081\u306b\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-81\">\u5bfe\u51e6\u6cd51: isset()\u306b\u3088\u308b\u4e8b\u524d\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<p>\u6700\u3082\u5b89\u5168\u3067\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5\u306f\u3001<code>isset()<\/code>\u3067\u307e\u305a\u5909\u6570\u306e\u5b58\u5728\u3092\u78ba\u8a8d\u3059\u308b\u3053\u3068\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ isset()\u3067\u4e8b\u524d\u306b\u30c1\u30a7\u30c3\u30af\nif (!isset($var) || is_null($var)) {\n    echo \"\u5909\u6570\u306f\u5b58\u5728\u3057\u306a\u3044\u304b\u3001NULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<p>\u305f\u3060\u3057\u3001<code>isset()<\/code>\u306fnull\u5024\u306b\u5bfe\u3057\u3066false\u3092\u8fd4\u3059\u305f\u3081\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u7c21\u7565\u5316\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u3088\u308a\u7c21\u6f54\u306a\u66f8\u304d\u65b9\nif (!isset($var)) {\n    echo \"\u5909\u6570\u306f\u5b58\u5728\u3057\u306a\u3044\u304b\u3001NULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-82\">\u5bfe\u51e6\u6cd52: \u30a8\u30e9\u30fc\u6291\u5236\u6f14\u7b97\u5b50\uff08\u975e\u63a8\u5968\uff09<\/h4>\n\n\n\n<p>\u30a8\u30e9\u30fc\u6291\u5236\u6f14\u7b97\u5b50\uff08@\uff09\u3092\u4f7f\u7528\u3057\u3066\u8b66\u544a\u3092\u6291\u5236\u3059\u308b\u3053\u3068\u3082\u53ef\u80fd\u3067\u3059\u304c\u3001\u4e00\u822c\u7684\u306b\u306f\u63a8\u5968\u3055\u308c\u307e\u305b\u3093\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30a8\u30e9\u30fc\u6291\u5236\u6f14\u7b97\u5b50\u306e\u4f7f\u7528\uff08\u975e\u63a8\u5968\uff09\nif (@is_null($undefinedVar)) {\n    echo \"\u5909\u6570\u306fNULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<p>\u3053\u306e\u65b9\u6cd5\u306f\u8b66\u544a\u3092\u975e\u8868\u793a\u306b\u3059\u308b\u3060\u3051\u3067\u3001\u6f5c\u5728\u7684\u306a\u554f\u984c\u3092\u96a0\u3057\u3066\u3057\u307e\u3046\u53ef\u80fd\u6027\u304c\u3042\u308b\u305f\u3081\u3001\u30c7\u30d0\u30c3\u30b0\u3092\u56f0\u96e3\u306b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-83\">\u5bfe\u51e6\u6cd53: \u5909\u6570\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u521d\u671f\u5316<\/h4>\n\n\n\n<p>\u5909\u6570\u3092\u4f7f\u7528\u3059\u308b\u524d\u306b\u660e\u793a\u7684\u306b\u521d\u671f\u5316\u3059\u308b\u3053\u3068\u3067\u3001\u672a\u5b9a\u7fa9\u5909\u6570\u306e\u554f\u984c\u3092\u9632\u3052\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u660e\u793a\u7684\u306a\u521d\u671f\u5316\n$var = null; \/\/ \u660e\u793a\u7684\u306bNULL\u3067\u521d\u671f\u5316\n\nif (is_null($var)) {\n    echo \"\u5909\u6570\u306fNULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-84\">\u5bfe\u51e6\u6cd54: array_key_exists()\u306b\u3088\u308b\u914d\u5217\u30ad\u30fc\u306e\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<p>\u914d\u5217\u306e\u30ad\u30fc\u306b\u5bfe\u3057\u3066\u306f\u3001<code>array_key_exists()<\/code>\u304c\u6709\u7528\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u914d\u5217\u30ad\u30fc\u306e\u5b58\u5728\u78ba\u8a8d\n$data = ['name' =&gt; 'John', 'email' =&gt; 'john@example.com'];\n\n\/\/ \u5b89\u5168\u306a\u65b9\u6cd5\nif (!array_key_exists('phone', $data) || is_null($data['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306f\u5b58\u5728\u3057\u306a\u3044\u304b\u3001NULL\u3067\u3059\";\n}\n\n\/\/ \u307e\u305f\u306f\nif (array_key_exists('phone', $data) &amp;&amp; !is_null($data['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7: \" . $data['phone'];\n} else {\n    echo \"\u6709\u52b9\u306a\u96fb\u8a71\u756a\u53f7\u304c\u3042\u308a\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-85\">\u5bfe\u51e6\u6cd55: Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08PHP 7.0\u4ee5\u964d\uff09<\/h4>\n\n\n\n<p>PHP 7.0\u4ee5\u964d\u3067\u306f\u3001Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u4f7f\u7528\u3057\u3066\u672a\u5b9a\u7fa9\u5909\u6570\u3084null\u5024\u306b\u5bfe\u3059\u308b\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u7c21\u5358\u306b\u8a2d\u5b9a\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Null\u5408\u4f53\u6f14\u7b97\u5b50\u306e\u4f7f\u7528\n$username = $user['name'] ?? '\u30b2\u30b9\u30c8';\n\n\/\/ \u3053\u308c\u306f\u4ee5\u4e0b\u3068\u540c\u7b49\n$username = isset($user['name']) ? $user['name'] : '\u30b2\u30b9\u30c8';\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-86\">\u5bfe\u51e6\u6cd56: error_reporting\u306e\u8a2d\u5b9a<\/h4>\n\n\n\n<p>\u958b\u767a\u74b0\u5883\u3067\u306f\u3001\u3059\u3079\u3066\u306e\u30a8\u30e9\u30fc\u3092\u8868\u793a\u3057\u3066\u4fee\u6b63\u3059\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u304c\u3001\u672c\u756a\u74b0\u5883\u3067\u306f<code>error_reporting<\/code>\u3092\u8abf\u6574\u3057\u3066<code>E_NOTICE<\/code>\u3092\u975e\u8868\u793a\u306b\u3059\u308b\u3053\u3068\u3082\u3042\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u672c\u756a\u74b0\u5883\u3067\u306e\u30a8\u30e9\u30fc\u30ec\u30dd\u30fc\u30c8\u30ec\u30d9\u30eb\u306e\u8abf\u6574\uff08\u975e\u63a8\u5968\uff09\nerror_reporting(E_ALL &amp; ~E_NOTICE);\n<\/pre>\n\n\n\n<p>\u305f\u3060\u3057\u3001\u3053\u306e\u65b9\u6cd5\u3082\u6f5c\u5728\u7684\u306a\u554f\u984c\u3092\u96a0\u3057\u3066\u3057\u307e\u3046\u305f\u3081\u3001\u6839\u672c\u7684\u306a\u89e3\u6c7a\u7b56\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-87\">\u30a8\u30e9\u30fc\u51e6\u7406\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h4>\n\n\n\n<p>\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u3088\u308b\u30a8\u30e9\u30fc\u3092\u9632\u3050\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306f\u3001\u6b21\u306e\u3068\u304a\u308a\u3067\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5909\u6570\u3092\u4f7f\u7528\u3059\u308b\u524d\u306b\u5fc5\u305a\u521d\u671f\u5316\u3059\u308b<\/li>\n\n\n\n<li><code>isset()<\/code>\u307e\u305f\u306f<code>array_key_exists()<\/code>\u3067\u5909\u6570\/\u30ad\u30fc\u306e\u5b58\u5728\u3092\u4e8b\u524d\u306b\u30c1\u30a7\u30c3\u30af\u3059\u308b<\/li>\n\n\n\n<li>PHP 7.0\u4ee5\u964d\u3067\u306f\u3001Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u7a4d\u6975\u7684\u306b\u6d3b\u7528\u3059\u308b<\/li>\n\n\n\n<li>\u30ea\u30af\u30a8\u30b9\u30c8\u30d1\u30e9\u30e1\u30fc\u30bf\u3084\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u3092\u53d6\u5f97\u3059\u308b\u969b\u306f\u3001<code>filter_input()<\/code>\u3084<code>$_GET['var'] ?? null<\/code>\u306e\u3088\u3046\u306a\u30d1\u30bf\u30fc\u30f3\u3092\u4f7f\u7528\u3059\u308b<\/li>\n\n\n\n<li>\u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\uff08PHPStan\u3001Psalm\u306a\u3069\uff09\u3092\u5c0e\u5165\u3057\u3066\u3001\u672a\u5b9a\u7fa9\u5909\u6570\u306e\u4f7f\u7528\u3092\u691c\u51fa\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u65b9\u6cd5\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u672a\u5b9a\u7fa9\u5909\u6570\u306b\u3088\u308b\u8b66\u544a\u3092\u52b9\u679c\u7684\u306b\u56de\u907f\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-88\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306enull\u30c1\u30a7\u30c3\u30af\u6642\u306e\u6ce8\u610f\u70b9<\/h3>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u5bfe\u3059\u308bnull\u30c1\u30a7\u30c3\u30af\u304c\u983b\u7e41\u306b\u5fc5\u8981\u306b\u306a\u308a\u307e\u3059\u304c\u3001\u3044\u304f\u3064\u304b\u306e\u843d\u3068\u3057\u7a74\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306enull\u30c1\u30a7\u30c3\u30af\u6642\u306e\u6ce8\u610f\u70b9\u3068\u6700\u9069\u306a\u65b9\u6cd5\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-89\">\u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9<\/h4>\n\n\n\n<p>PHP\u3067\u306f\u3001\u5b58\u5728\u3057\u306a\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u3068\u8b66\u544a\u304c\u767a\u751f\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    public $name = \"John\";\n    \/\/ phone\u30d7\u30ed\u30d1\u30c6\u30a3\u306f\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u306a\u3044\n}\n\n$user = new User();\n\n\/\/ \u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u5bfe\u3059\u308bis_null()\nif (is_null($user-&gt;phone)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\";\n}\n\/\/ \u51fa\u529b: Warning: Undefined property: User::$phone in \/path\/to\/file.php on line X\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-90\">\u5bfe\u51e6\u6cd51: property_exists()\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p><code>property_exists()<\/code>\u95a2\u6570\u3092\u4f7f\u7528\u3057\u3066\u3001\u5148\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u306e\u5b58\u5728\u3092\u78ba\u8a8d\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">if (property_exists($user, 'phone')) {\n    if (is_null($user-&gt;phone)) {\n        echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\u304c\u3001\u30d7\u30ed\u30d1\u30c6\u30a3\u306f\u5b58\u5728\u3057\u307e\u3059\";\n    } else {\n        echo \"\u96fb\u8a71\u756a\u53f7: \" . $user-&gt;phone;\n    }\n} else {\n    echo \"\u96fb\u8a71\u756a\u53f7\u30d7\u30ed\u30d1\u30c6\u30a3\u306f\u5b58\u5728\u3057\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-91\">\u5bfe\u51e6\u6cd52: isset()\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/h4>\n\n\n\n<p><code>isset()<\/code>\u306f\u3001\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3057\u306a\u3044\u304bnull\u306e\u5834\u5408\u306bfalse\u3092\u8fd4\u3059\u305f\u3081\u3001\u7c21\u6f54\u306b\u66f8\u3051\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">if (!isset($user-&gt;phone)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306f\u5b58\u5728\u3057\u306a\u3044\u304b\u3001NULL\u3067\u3059\";\n} else {\n    echo \"\u96fb\u8a71\u756a\u53f7: \" . $user-&gt;phone;\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-92\">\u5bfe\u51e6\u6cd53: __get()\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u306e\u6d3b\u7528<\/h4>\n\n\n\n<p>\u9b54\u8853\u30e1\u30bd\u30c3\u30c9<code>__get()<\/code>\u3092\u5b9f\u88c5\u3059\u308b\u3053\u3068\u3067\u3001\u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u3088\u308a\u67d4\u8edf\u306b\u5236\u5fa1\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    private $data = [\n        'name' =&gt; 'John',\n        'email' =&gt; 'john@example.com'\n    ];\n    \n    public function __get($name) {\n        return $this-&gt;data[$name] ?? null;\n    }\n}\n\n$user = new User();\n\n\/\/ \u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u5bfe\u3059\u308b\u30a2\u30af\u30bb\u30b9\u3067\u3082\u8b66\u544a\u306f\u767a\u751f\u3057\u306a\u3044\nif (is_null($user-&gt;phone)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-93\">\u5bfe\u51e6\u6cd54: Nullsafe\u6f14\u7b97\u5b50\u306e\u6d3b\u7528\uff08PHP 8.0\u4ee5\u964d\uff09<\/h4>\n\n\n\n<p>PHP 8.0\u4ee5\u964d\u3067\u306f\u3001Nullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\u3092\u4f7f\u7528\u3057\u3066\u5b89\u5168\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 8.0\u4ee5\u964d\n$phone = $user?-&gt;phone;\n\nif (is_null($phone)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\uff08\u307e\u305f\u306f$user\u304cNULL\u3067\u3059\uff09\";\n} else {\n    echo \"\u96fb\u8a71\u756a\u53f7: \" . $phone;\n}\n<\/pre>\n\n\n\n<p>\u3053\u308c\u306f<code>$user<\/code>\u81ea\u4f53\u304cnull\u306e\u5834\u5408\u3082\u5b89\u5168\u306b\u51e6\u7406\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-94\">\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8\/\u30d7\u30ed\u30c6\u30af\u30c6\u30c3\u30c9\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9<\/h4>\n\n\n\n<p>\u53ef\u8996\u6027\u304cprivate\u3084protected\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u306f\u3001\u30af\u30e9\u30b9\u5916\u90e8\u304b\u3089\u76f4\u63a5\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u305b\u3093\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    private $name = \"John\";\n    protected $email = \"john@example.com\";\n}\n\n$user = new User();\n\n\/\/ \u30d7\u30e9\u30a4\u30d9\u30fc\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9\uff08\u30a8\u30e9\u30fc\uff09\nif (is_null($user-&gt;name)) {\n    echo \"\u540d\u524d\u306fNULL\u3067\u3059\";\n}\n\/\/ \u51fa\u529b: Fatal error: Uncaught Error: Cannot access private property User::$name\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-95\">\u5bfe\u51e6\u6cd5: \u30a2\u30af\u30bb\u30b5\u30e1\u30bd\u30c3\u30c9\uff08\u30b2\u30c3\u30bf\u30fc\uff09\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p>\u9069\u5207\u306a\u30a2\u30af\u30bb\u30b5\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\u3059\u308b\u3053\u3068\u3067\u3001\u5b89\u5168\u306b\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8\/\u30d7\u30ed\u30c6\u30af\u30c6\u30c3\u30c9\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    private $name = \"John\";\n    protected $email = \"john@example.com\";\n    private $phone = null;\n    \n    public function getName() {\n        return $this-&gt;name;\n    }\n    \n    public function getEmail() {\n        return $this-&gt;email;\n    }\n    \n    public function getPhone() {\n        return $this-&gt;phone;\n    }\n}\n\n$user = new User();\n\n\/\/ \u30b2\u30c3\u30bf\u30fc\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\nif (is_null($user-&gt;getPhone())) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-96\">\u52d5\u7684\u30d7\u30ed\u30d1\u30c6\u30a3\u3068\u30ea\u30d5\u30ec\u30af\u30b7\u30e7\u30f3<\/h4>\n\n\n\n<p>\u3088\u308a\u8907\u96d1\u306a\u30b1\u30fc\u30b9\u3067\u306f\u3001PHP\u306e\u30ea\u30d5\u30ec\u30af\u30b7\u30e7\u30f3API\u3092\u4f7f\u7528\u3057\u3066\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    private $name = \"John\";\n    protected $email = \"john@example.com\";\n    private $phone = null;\n}\n\n$user = new User();\n\n\/\/ \u30ea\u30d5\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u4f7f\u7528\u3057\u305f\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9\n$reflection = new ReflectionProperty(User::class, 'phone');\n$reflection-&gt;setAccessible(true);\n$phone = $reflection-&gt;getValue($user);\n\nif (is_null($phone)) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\";\n}\n<\/pre>\n\n\n\n<p>\u305f\u3060\u3057\u3001\u3053\u308c\u306f\u30c7\u30d0\u30c3\u30b0\u3084\u30c6\u30b9\u30c8\u76ee\u7684\u4ee5\u5916\u3067\u306f\u4e00\u822c\u7684\u306b\u907f\u3051\u308b\u3079\u304d\u30a2\u30d7\u30ed\u30fc\u30c1\u3067\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-97\">\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h4>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306enull\u30c1\u30a7\u30c3\u30af\u306b\u95a2\u3059\u308b\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u4f7f\u7528\u3059\u308b\u524d\u306b\u521d\u671f\u5316\u3059\u308b\u7fd2\u6163\u3092\u3064\u3051\u308b<\/li>\n\n\n\n<li>\u30d1\u30d6\u30ea\u30c3\u30af\u30d7\u30ed\u30d1\u30c6\u30a3\u3088\u308a\u3082\u3001\u9069\u5207\u306a\u30b2\u30c3\u30bf\u30fc\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\u3059\u308b<\/li>\n\n\n\n<li>PHP 8.0\u4ee5\u964d\u3067\u306fNullsafe\u6f14\u7b97\u5b50\uff08?-&gt;\uff09\u3092\u7a4d\u6975\u7684\u306b\u6d3b\u7528\u3059\u308b<\/li>\n\n\n\n<li>\u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u9632\u3050\u305f\u3081\u306e\u30c7\u30fc\u30bf\u691c\u8a3c\u3092\u5b9f\u88c5\u3059\u308b<\/li>\n\n\n\n<li>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5e38\u306b\u4e00\u8cab\u3057\u305f\u72b6\u614b\u3067\u3042\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u65b9\u6cd5\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u95a2\u9023\u3059\u308b\u30a8\u30e9\u30fc\u3092\u52b9\u679c\u7684\u306b\u9632\u6b62\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-98\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3068\u306a\u308b\u5834\u9762\u3068\u5bfe\u7b56<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u306f\u5358\u7d14\u306a\u95a2\u6570\u3067\u3059\u304c\u3001\u7279\u5b9a\u306e\u72b6\u6cc1\u4e0b\u3067\u306f\u601d\u308f\u306c\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u306b\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3059\u308b\u5834\u9762\u3068\u3001\u305d\u308c\u3092\u6539\u5584\u3059\u308b\u305f\u3081\u306e\u5bfe\u7b56\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-99\">\u5927\u91cf\u30eb\u30fc\u30d7\u5185\u3067\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p>\u6700\u3082\u4e00\u822c\u7684\u306a\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u554f\u984c\u306f\u3001\u5927\u91cf\u306e\u30eb\u30fc\u30d7\u5185\u3067<code>is_null()<\/code>\u3092\u7e70\u308a\u8fd4\u3057\u547c\u3073\u51fa\u3059\u5834\u5408\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u554f\u984c\u304c\u751f\u3058\u308b\u53ef\u80fd\u6027\u306e\u3042\u308b\u30b3\u30fc\u30c9\n$results = [];\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $value = getSomeValue($i); \/\/ \u4f55\u3089\u304b\u306e\u5024\u3092\u53d6\u5f97\n    if (!is_null($value)) {\n        $results[] = $value;\n    }\n}\n<\/pre>\n\n\n\n<p>\u6570\u767e\u4e07\u56de\u306e\u30eb\u30fc\u30d7\u3067\u306f\u3001\u95a2\u6570\u547c\u3073\u51fa\u3057\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u7a4d\u307f\u91cd\u306a\u308a\u3001\u51e6\u7406\u6642\u9593\u304c\u5897\u52a0\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-100\">\u5bfe\u7b561: \u6bd4\u8f03\u6f14\u7b97\u5b50\u306e\u4f7f\u7528<\/h4>\n\n\n\n<p>\u95a2\u6570\u547c\u3073\u51fa\u3057\u3092\u907f\u3051\u3001\u4ee3\u308f\u308a\u306b\u53b3\u5bc6\u306a\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08<code>=== null<\/code>\uff09\u3092\u4f7f\u7528\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u3088\u308a\u52b9\u7387\u7684\u306a\u65b9\u6cd5\n$results = [];\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $value = getSomeValue($i);\n    if ($value !== null) {\n        $results[] = $value;\n    }\n}\n<\/pre>\n\n\n\n<p>\u95a2\u6570\u547c\u3073\u51fa\u3057\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u306a\u304f\u306a\u308b\u305f\u3081\u3001\u7279\u306b\u5927\u91cf\u306e\u30eb\u30fc\u30d7\u3067\u52b9\u679c\u7684\u3067\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-101\">\u5bfe\u7b562: array_filter()\u306e\u6d3b\u7528<\/h4>\n\n\n\n<p>\u914d\u5217\u64cd\u4f5c\u3067\u306f\u3001<code>array_filter()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u30b3\u30fc\u30c9\u3092\u7c21\u6f54\u306b\u3057\u3001\u5185\u90e8\u6700\u9069\u5316\u306e\u6069\u6075\u3092\u53d7\u3051\u3089\u308c\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5927\u91cf\u306e\u914d\u5217\u8981\u7d20\u3092\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u3059\u308b\u5834\u5408\n$values = getLotsOfValues(); \/\/ \u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u53d6\u5f97\n\n\/\/ \u95a2\u6570\u547c\u3073\u51fa\u3057\u3092\u4f7f\u308f\u306a\u3044\u65b9\u6cd5\n$results = array_filter($values, function($value) {\n    return $value !== null;\n});\n\n\/\/ \u77ed\u3044\u69cb\u6587\uff08PHP 7.4\u4ee5\u964d\uff09\n$results = array_filter($values, fn($value) =&gt; $value !== null);\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-102\">\u5bfe\u7b563: \u4e8b\u524d\u30c1\u30a7\u30c3\u30af\u306b\u3088\u308b\u6700\u9069\u5316<\/h4>\n\n\n\n<p>\u30eb\u30fc\u30d7\u5185\u3067\u4e00\u6642\u5909\u6570\u306b\u683c\u7d0d\u3057\u3066\u518d\u5229\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u95a2\u6570\u547c\u3073\u51fa\u3057\u56de\u6570\u3092\u6e1b\u3089\u305b\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u8907\u96d1\u306a\u6761\u4ef6\u3092\u542b\u3080\u30eb\u30fc\u30d7\u306e\u6700\u9069\u5316\nforeach ($items as $item) {\n    \/\/ \u6700\u521d\u306b\u30c1\u30a7\u30c3\u30af\u3057\u3066\u7d50\u679c\u3092\u5909\u6570\u306b\u683c\u7d0d\n    $isNameNull = is_null($item-&gt;name);\n    $isEmailNull = is_null($item-&gt;email);\n    \n    \/\/ \u4fdd\u5b58\u3057\u305f\u7d50\u679c\u3092\u518d\u5229\u7528\n    if ($isNameNull &amp;&amp; !$isEmailNull) {\n        \/\/ \u51e6\u74061\n    } else if (!$isNameNull &amp;&amp; $isEmailNull) {\n        \/\/ \u51e6\u74062\n    } else if (!$isNameNull &amp;&amp; !$isEmailNull) {\n        \/\/ \u51e6\u74063\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-103\">\u540d\u524d\u7a7a\u9593\u5185\u3067\u306e\u547c\u3073\u51fa\u3057<\/h4>\n\n\n\n<p>\u524d\u8ff0\u306e\u3088\u3046\u306b\u3001\u540d\u524d\u7a7a\u9593\u5185\u3067\u306e\u95a2\u6570\u547c\u3073\u51fa\u3057\u3067\u306f\u3001\u30d5\u30eb\u30d1\u30b9\u3092\u6307\u5b9a\u3059\u308b\u3053\u3068\u3067\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u5411\u4e0a\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">namespace App\\Services;\n\nclass DataProcessor\n{\n    public function process($items)\n    {\n        \/\/ \u975e\u52b9\u7387\u306a\u547c\u3073\u51fa\u3057\n        $filtered1 = array_filter($items, function($item) {\n            return is_null($item); \/\/ \u540d\u524d\u7a7a\u9593\u89e3\u6c7a\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u3042\u308a\n        });\n        \n        \/\/ \u52b9\u7387\u7684\u306a\u547c\u3073\u51fa\u3057\n        $filtered2 = array_filter($items, function($item) {\n            return \\is_null($item); \/\/ \u30b0\u30ed\u30fc\u30d0\u30eb\u95a2\u6570\u3092\u76f4\u63a5\u547c\u3073\u51fa\u3057\n        });\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-104\">JSON\u64cd\u4f5c\u3067\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316<\/h4>\n\n\n\n<p>JSON\u30c7\u30fc\u30bf\u3092\u6271\u3046\u969b\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5411\u4e0a\u7b56\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5927\u91cf\u306eJSON\u30c7\u30fc\u30bf\u3092\u51e6\u7406\u3059\u308b\u4f8b\n$jsonData = json_decode($largeJsonResponse, true);\n\n\/\/ \u975e\u52b9\u7387\u306a\u65b9\u6cd5: \u3059\u3079\u3066\u306e\u8981\u7d20\u3092\u500b\u5225\u306b\u30c1\u30a7\u30c3\u30af\n$validItems = [];\nforeach ($jsonData['items'] as $item) {\n    if (!is_null($item['price']) &amp;&amp; !is_null($item['quantity'])) {\n        $validItems[] = $item;\n    }\n}\n\n\/\/ \u52b9\u7387\u7684\u306a\u65b9\u6cd5: \u4e00\u5ea6\u306b\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\n$validItems = array_filter($jsonData['items'], function($item) {\n    return isset($item['price'], $item['quantity']); \/\/ isset()\u306f\u8907\u6570\u306e\u5024\u3092\u30c1\u30a7\u30c3\u30af\u53ef\u80fd\n});\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-105\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u3078\u306e\u7e70\u308a\u8fd4\u3057\u30a2\u30af\u30bb\u30b9\u306e\u6700\u9069\u5316<\/h4>\n\n\n\n<p>\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u7e70\u308a\u8fd4\u3057\u30a2\u30af\u30bb\u30b9\u3059\u308b\u5834\u5408\u306f\u3001\u7d50\u679c\u3092\u30ad\u30e3\u30c3\u30b7\u30e5\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u975e\u52b9\u7387\u306a\u65b9\u6cd5: \u540c\u3058\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u7e70\u308a\u8fd4\u3057\u30a2\u30af\u30bb\u30b9\n$totalPrice = 0;\nforeach ($products as $product) {\n    if (!is_null($product-&gt;price)) {\n        $totalPrice += $product-&gt;price;\n    }\n    \n    if (!is_null($product-&gt;price) &amp;&amp; $product-&gt;price &gt; 100) {\n        $expensiveProducts[] = $product;\n    }\n}\n\n\/\/ \u52b9\u7387\u7684\u306a\u65b9\u6cd5: \u7d50\u679c\u3092\u30ed\u30fc\u30ab\u30eb\u5909\u6570\u306b\u30ad\u30e3\u30c3\u30b7\u30e5\n$totalPrice = 0;\nforeach ($products as $product) {\n    $price = $product-&gt;price; \/\/ \u4e00\u5ea6\u3060\u3051\u30a2\u30af\u30bb\u30b9\n    $isPriceNull = is_null($price); \/\/ \u7d50\u679c\u3092\u30ad\u30e3\u30c3\u30b7\u30e5\n    \n    if (!$isPriceNull) {\n        $totalPrice += $price;\n        \n        if ($price &gt; 100) {\n            $expensiveProducts[] = $product;\n        }\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-106\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6e2c\u5b9a\u306e\u91cd\u8981\u6027<\/h4>\n\n\n\n<p>\u5b9f\u969b\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6539\u5584\u306b\u306f\u3001\u307e\u305a\u6e2c\u5b9a\u304c\u91cd\u8981\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6e2c\u5b9a\u95a2\u6570\nfunction measureTime($callback, $iterations = 1000) {\n    $start = microtime(true);\n    for ($i = 0; $i &lt; $iterations; $i++) {\n        $callback();\n    }\n    $end = microtime(true);\n    return $end - $start;\n}\n\n\/\/ is_null()\u3068===null\u306e\u6bd4\u8f03\n$var = null;\n$time1 = measureTime(function() use ($var) {\n    is_null($var);\n});\n\n$time2 = measureTime(function() use ($var) {\n    $var === null;\n});\n\necho \"is_null(): \" . $time1 . \" \u79d2\\n\";\necho \"=== null: \" . $time2 . \" \u79d2\\n\";\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-107\">\u6700\u9069\u5316\u306e\u57fa\u672c\u539f\u5247<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u904e\u5270\u6700\u9069\u5316\u3092\u907f\u3051\u308b<\/strong> \u2013 \u5b9f\u969b\u306e\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3092\u7279\u5b9a\u3057\u3066\u304b\u3089\u6700\u9069\u5316\u3059\u308b<\/li>\n\n\n\n<li><strong>\u6e2c\u5b9a\u3057\u3066\u304b\u3089\u6700\u9069\u5316<\/strong> \u2013 \u63a8\u6e2c\u3067\u306f\u306a\u304f\u5b9f\u6e2c\u30c7\u30fc\u30bf\u306b\u57fa\u3065\u3044\u3066\u5224\u65ad\u3059\u308b<\/li>\n\n\n\n<li><strong>\u8aad\u307f\u3084\u3059\u3055\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30d0\u30e9\u30f3\u30b9<\/strong> \u2013 \u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3082\u91cd\u8981\u306a\u8981\u7d20<\/li>\n\n\n\n<li><strong>\u5b9f\u74b0\u5883\u3067\u306e\u691c\u8a3c<\/strong> \u2013 \u958b\u767a\u74b0\u5883\u3068\u672c\u756a\u74b0\u5883\u3067\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5dee\u3092\u8003\u616e\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<p>\u591a\u304f\u306e\u5834\u5408\u3001<code>is_null()<\/code>\u3068<code>=== null<\/code>\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5dee\u306f\u5c0f\u3055\u3044\u3067\u3059\u304c\u3001\u5927\u91cf\u306e\u7e70\u308a\u8fd4\u3057\u51e6\u7406\u3084\u91cd\u8981\u306a\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u8981\u4ef6\u304c\u3042\u308b\u5834\u5408\u306f\u3001\u4e0a\u8a18\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\u3092\u691c\u8a0e\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-108\">\u914d\u5217\u64cd\u4f5c\u6642\u306e\u843d\u3068\u3057\u7a74\u3068\u56de\u907f\u7b56<\/h3>\n\n\n\n<p>\u914d\u5217\u64cd\u4f5c\u306f PHP \u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u57fa\u672c\u3067\u3059\u304c\u3001<code>is_null()<\/code> \u95a2\u6570\u3092\u914d\u5217\u8981\u7d20\u306b\u4f7f\u7528\u3059\u308b\u969b\u306b\u306f\u3001\u3044\u304f\u3064\u304b\u306e\u843d\u3068\u3057\u7a74\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u554f\u984c\u3068\u305d\u306e\u56de\u907f\u7b56\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-109\">\u914d\u5217\u30ad\u30fc\u3068\u5024\u306e\u5b58\u5728\u30c1\u30a7\u30c3\u30af\u306e\u6df7\u540c<\/h4>\n\n\n\n<p>\u4e00\u822c\u7684\u306a\u8aa4\u308a\u306f\u3001\u914d\u5217\u5185\u306e\u5024\u304c<code>null<\/code>\u3067\u3042\u308b\u3053\u3068\u3068\u3001\u30ad\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\u3053\u3068\u3092\u6df7\u540c\u3059\u308b\u3053\u3068\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u914d\u5217\u306e\u5b9a\u7fa9\n$user = [\n    'name' =&gt; 'John',\n    'email' =&gt; 'john@example.com',\n    'phone' =&gt; null \/\/ \u660e\u793a\u7684\u306bnull\n];\n\n\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (is_null($user['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\"; \/\/ \u6b63\u3057\u304f\u52d5\u4f5c\n}\n\nif (is_null($user['address'])) {\n    echo \"\u4f4f\u6240\u306fNULL\u3067\u3059\"; \/\/ \u30ad\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\u305f\u3081\u8b66\u544a\u304c\u767a\u751f\n}\n\/\/ Warning: Undefined array key \"address\" in \/path\/to\/file.php on line X\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-110\">\u5bfe\u7b56: isset()\u307e\u305f\u306farray_key_exists()\u306b\u3088\u308b\u4e8b\u524d\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b89\u5168\u306a\u30a2\u30d7\u30ed\u30fc\u30c1: \u4e8b\u524d\u306b\u30ad\u30fc\u306e\u5b58\u5728\u3092\u30c1\u30a7\u30c3\u30af\nif (isset($user['address'])) {\n    if (is_null($user['address'])) {\n        echo \"\u4f4f\u6240\u306fNULL\u3067\u3059\";\n    } else {\n        echo \"\u4f4f\u6240: \" . $user['address'];\n    }\n} else {\n    echo \"\u4f4f\u6240\u60c5\u5831\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n\n\/\/ \u307e\u305f\u306f array_key_exists() \u3092\u4f7f\u7528\nif (array_key_exists('address', $user)) {\n    if (is_null($user['address'])) {\n        echo \"\u4f4f\u6240\u306fNULL\u3067\u3059\";\n    } else {\n        echo \"\u4f4f\u6240: \" . $user['address'];\n    }\n} else {\n    echo \"\u4f4f\u6240\u60c5\u5831\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-111\">isset()\u3068array_key_exists()\u306e\u9055\u3044<\/h4>\n\n\n\n<p><code>isset()<\/code>\u3068<code>array_key_exists()<\/code>\u306e\u4e3b\u306a\u9055\u3044\u306f\u3001<code>null<\/code>\u5024\u306e\u6271\u3044\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">$data = [\n    'key1' =&gt; 'value1',\n    'key2' =&gt; null\n];\n\nvar_dump(isset($data['key1']));           \/\/ bool(true)\nvar_dump(isset($data['key2']));           \/\/ bool(false) - \u30ad\u30fc\u306f\u5b58\u5728\u3059\u308b\u304cnull\u5024\nvar_dump(isset($data['nonexistent']));    \/\/ bool(false) - \u30ad\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\n\nvar_dump(array_key_exists('key1', $data));        \/\/ bool(true)\nvar_dump(array_key_exists('key2', $data));        \/\/ bool(true) - \u5024\u304cnull\u3067\u3082true\u3092\u8fd4\u3059\nvar_dump(array_key_exists('nonexistent', $data)); \/\/ bool(false)\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-112\">\u591a\u6b21\u5143\u914d\u5217\u64cd\u4f5c\u3067\u306e\u6ce8\u610f\u70b9<\/h4>\n\n\n\n<p>\u591a\u6b21\u5143\u914d\u5217\u3067\u306f\u3001\u30a8\u30e9\u30fc\u304c\u8907\u96d1\u306b\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u591a\u6b21\u5143\u914d\u5217\n$user = [\n    'name' =&gt; 'John',\n    'contact' =&gt; [\n        'email' =&gt; 'john@example.com',\n        'phone' =&gt; null\n    ]\n];\n\n\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (is_null($user['contact']['phone'])) {\n    echo \"\u96fb\u8a71\u756a\u53f7\u306fNULL\u3067\u3059\"; \/\/ \u6b63\u3057\u304f\u52d5\u4f5c\n}\n\nif (is_null($user['contact']['fax'])) {\n    echo \"FAX\u756a\u53f7\u306fNULL\u3067\u3059\"; \/\/ \u30ad\u30fc\u304c\u5b58\u5728\u3057\u306a\u3044\u305f\u3081\u8b66\u544a\n}\n\nif (is_null($user['address']['zipcode'])) {\n    echo \"\u90f5\u4fbf\u756a\u53f7\u306fNULL\u3067\u3059\"; \/\/ 'address'\u30ad\u30fc\u81ea\u4f53\u304c\u5b58\u5728\u3057\u306a\u3044\u305f\u3081\u81f4\u547d\u7684\u30a8\u30e9\u30fc\n}\n\/\/ Fatal error: Uncaught Error: Trying to access array offset on value of type null\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-113\">\u5bfe\u7b56: \u30cd\u30b9\u30c8\u3057\u305f\u9023\u60f3\u914d\u5217\u306e\u5b89\u5168\u306a\u64cd\u4f5c<\/h4>\n\n\n\n<p>\u968e\u5c64\u7684\u306b\u30c1\u30a7\u30c3\u30af\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b89\u5168\u306a\u30a2\u30d7\u30ed\u30fc\u30c1\nif (isset($user['contact']) &amp;&amp; isset($user['contact']['fax'])) {\n    if (is_null($user['contact']['fax'])) {\n        echo \"FAX\u756a\u53f7\u306fNULL\u3067\u3059\";\n    }\n} else {\n    echo \"FAX\u60c5\u5831\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n\n\/\/ \u307e\u305f\u306f PHP 7.0\u4ee5\u964d\u3067\u306fNull\u5408\u4f53\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\n$fax = $user['contact']['fax'] ?? null;\nif (is_null($fax)) {\n    echo \"FAX\u756a\u53f7\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n}\n\n\/\/ PHP 8.0\u4ee5\u964d\u3067\u306fNullsafe\u6f14\u7b97\u5b50\u3082\u4f7f\u7528\u53ef\u80fd\n$zipcode = $user['address']['zipcode'] ?? null; \/\/ PHP 7.0\u4ee5\u964d\n$zipcode = $user['address']?-&gt;zipcode; \/\/ PHP 8.0\u4ee5\u964d\uff08\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u5834\u5408\uff09\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-114\">\u914d\u5217\u306e\u5024\u3068\u30ad\u30fc\u306enull\u30c1\u30a7\u30c3\u30af\u3092\u533a\u5225\u3059\u308b<\/h4>\n\n\n\n<p>\u5024\u306e\u30c1\u30a7\u30c3\u30af\u3068\u30ad\u30fc\u306e\u5b58\u5728\u30c1\u30a7\u30c3\u30af\u3092\u660e\u78ba\u306b\u533a\u5225\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u826f\u3044\u4f8b: \u5024\u3068\u30ad\u30fc\u306e\u5b58\u5728\u3092\u660e\u793a\u7684\u306b\u533a\u5225\nfunction getUserData($user, $key) {\n    \/\/ 1. \u30ad\u30fc\u306e\u5b58\u5728\u30c1\u30a7\u30c3\u30af\n    if (!array_key_exists($key, $user)) {\n        return \"\u60c5\u5831\u304c\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n    }\n    \n    \/\/ 2. \u5024\u306enull\u30c1\u30a7\u30c3\u30af\n    if (is_null($user[$key])) {\n        return \"\u60c5\u5831\u306f\u767b\u9332\u3055\u308c\u3066\u3044\u307e\u3059\u304c\u3001\u5024\u306fNULL\u3067\u3059\";\n    }\n    \n    \/\/ 3. \u901a\u5e38\u306e\u5024\u306e\u51e6\u7406\n    return $user[$key];\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-115\">\u914d\u5217\u64cd\u4f5c\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30ad\u30fc\u306e\u5b58\u5728\u3068\u5024\u306enull\u3092\u533a\u5225\u3059\u308b<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u30ad\u30fc\u306e\u5b58\u5728\u306f<code>array_key_exists()<\/code>\u307e\u305f\u306f<code>isset()<\/code>\u3067\u30c1\u30a7\u30c3\u30af<\/li>\n\n\n\n<li>\u5024\u304cnull\u304b\u3069\u3046\u304b\u306f<code>is_null()<\/code>\u3067\u30c1\u30a7\u30c3\u30af<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\u30d1\u30bf\u30fc\u30f3\u3092\u4f7f\u7528\u3059\u308b<\/strong>\n<ul class=\"wp-block-list\">\n<li>PHP 7\u4ee5\u964d\u3067\u306f\u3001Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09\u3092\u6d3b\u7528<\/li>\n\n\n\n<li>\u968e\u5c64\u7684\u306a\u30c1\u30a7\u30c3\u30af\u3001\u307e\u305f\u306f\u914d\u5217\u306e\u5b58\u5728\u3092\u4e8b\u524d\u306b\u78ba\u8a8d<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u591a\u6b21\u5143\u914d\u5217\u3067\u306f\u6ce8\u610f\u304c\u5fc5\u8981<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u89aa\u30ad\u30fc\u304b\u3089\u9806\u306b\u30c1\u30a7\u30c3\u30af<\/li>\n\n\n\n<li>\u4e00\u3064\u306e\u968e\u5c64\u3067\u5b58\u5728\u3057\u306a\u3044\u30ad\u30fc\u304c\u3042\u308b\u3068\u3001\u305d\u306e\u4e0b\u306e\u968e\u5c64\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3067\u30a8\u30e9\u30fc\u304c\u767a\u751f<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u30c7\u30fc\u30bf\u306e\u691c\u8a3c\u3068\u6b63\u898f\u5316<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u53ef\u80fd\u306a\u9650\u308a\u3001\u914d\u5217\u30c7\u30fc\u30bf\u3092\u65e9\u671f\u306b\u691c\u8a3c\u30fb\u6b63\u898f\u5316<\/li>\n\n\n\n<li>\u5b58\u5728\u3059\u3079\u304d\u30ad\u30fc\u304c\u5fc5\u305a\u5b58\u5728\u3059\u308b\u3088\u3046\u306b\u3059\u308b<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>RecursiveArrayIterator\u306e\u6d3b\u7528<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u8907\u96d1\u306a\u591a\u6b21\u5143\u914d\u5217\u3067\u306f\u3001RecursiveArrayIterator\u3092\u4f7f\u7528\u3057\u3066\u5b89\u5168\u306b\u53cd\u5fa9\u51e6\u7406<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u65b9\u6cd5\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u914d\u5217\u64cd\u4f5c\u306b\u304a\u3051\u308b<code>is_null()<\/code>\u95a2\u9023\u306e\u30a8\u30e9\u30fc\u3092\u52b9\u679c\u7684\u306b\u9632\u6b62\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-116\">\u307e\u3068\u3081\uff1a\u72b6\u6cc1\u306b\u5fdc\u3058\u305fis_null\u95a2\u6570\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528\u6cd5<\/h2>\n\n\n\n<p>\u672c\u8a18\u4e8b\u3067\u306f\u3001PHP\u306e<code>is_null()<\/code>\u95a2\u6570\u306b\u3064\u3044\u3066\u3001\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u304b\u3089\u5fdc\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3001\u3088\u304f\u3042\u308b\u30a8\u30e9\u30fc\u3068\u305d\u306e\u5bfe\u51e6\u6cd5\u307e\u3067\u8a73\u3057\u304f\u89e3\u8aac\u3057\u3066\u304d\u307e\u3057\u305f\u3002\u3053\u3053\u3067\u306f\u3001\u3053\u308c\u307e\u3067\u306e\u5185\u5bb9\u3092\u7dcf\u62ec\u3057\u3001\u72b6\u6cc1\u306b\u5fdc\u3058\u305f<code>is_null()<\/code>\u95a2\u6570\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528\u6cd5\u3092\u307e\u3068\u3081\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-117\">\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\u30c1\u30fc\u30c8\u30b7\u30fc\u30c8<\/h3>\n\n\n\n<p>\u69d8\u3005\u306a\u30b7\u30fc\u30f3\u3067\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\u3092\u9078\u629e\u3067\u304d\u308b\u3088\u3046\u3001\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\u306e\u30c1\u30fc\u30c8\u30b7\u30fc\u30c8\u3092\u4f5c\u6210\u3057\u307e\u3057\u305f\u3002\u3053\u306e\u30c1\u30fc\u30c8\u30b7\u30fc\u30c8\u3092\u53c2\u8003\u306b\u3001\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u3068\u53ef\u8aad\u6027\u3092\u5411\u4e0a\u3055\u305b\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-118\">\u5909\u6570\u306e\u30c1\u30a7\u30c3\u30af<\/h4>\n\n\n<div id=\"id-ee446ddc-3264-4ecd-9a20-1e7d71ae1b93\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>\u5909\u6570\u304c\u5b58\u5728\u3059\u308b\u304b<\/td><td><code>isset()<\/code><\/td><td><code>if (isset($var)) { ... }<\/code><\/td><\/tr><tr><td>\u5909\u6570\u304cNULL\u304b<\/td><td><code>is_null()<\/code> \u307e\u305f\u306f <code>=== null<\/code><\/td><td><code>if (is_null($var)) { ... }<\/code> \u307e\u305f\u306f <code>if ($var === null) { ... }<\/code><\/td><\/tr><tr><td>\u5909\u6570\u304c\u5b58\u5728\u3057\u306a\u3044\u304bNULL\u304b<\/td><td><code>!isset()<\/code><\/td><td><code>if (!isset($var)) { ... }<\/code><\/td><\/tr><tr><td>\u5909\u6570\u304c\u300c\u7a7a\u300d\u304b<\/td><td><code>empty()<\/code><\/td><td><code>if (empty($var)) { ... }<\/code><\/td><\/tr><tr><td>\u5909\u6570\u304c\u5b58\u5728\u3057\u3001\u304b\u3064NULL\u3067\u306a\u3044\u304b<\/td><td><code>isset()<\/code> \u304b\u3064 <code>!is_null()<\/code><\/td><td><code>if (isset($var) &amp;&amp; !is_null($var)) { ... }<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h4 class=\"wp-block-heading\" id=\"i-119\">\u914d\u5217\u64cd\u4f5c<\/h4>\n\n\n<div id=\"id-61937468-b585-490d-999f-09cd5db9002f\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>\u914d\u5217\u30ad\u30fc\u304c\u5b58\u5728\u3059\u308b\u304b<\/td><td><code>array_key_exists()<\/code><\/td><td><code>if (array_key_exists('key', $array)) { ... }<\/code><\/td><\/tr><tr><td>\u914d\u5217\u30ad\u30fc\u304c\u5b58\u5728\u3057\u3001\u5024\u304cNULL\u3067\u306a\u3044\u304b<\/td><td><code>isset()<\/code><\/td><td><code>if (isset($array['key'])) { ... }<\/code><\/td><\/tr><tr><td>\u914d\u5217\u30ad\u30fc\u304c\u5b58\u5728\u3057\u3001\u5024\u304cNULL\u304b<\/td><td><code>array_key_exists()<\/code> \u304b\u3064 <code>is_null()<\/code><\/td><td><code>if (array_key_exists('key', $array) &amp;&amp; is_null($array['key'])) { ... }<\/code><\/td><\/tr><tr><td>\u5b89\u5168\u306b\u914d\u5217\u5024\u3092\u53d6\u5f97\uff08PHP 7+\uff09<\/td><td>Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08??\uff09<\/td><td><code>$value = $array['key'] ?? '\u30c7\u30d5\u30a9\u30eb\u30c8\u5024';<\/code><\/td><\/tr><tr><td>\u591a\u6b21\u5143\u914d\u5217\u3092\u5b89\u5168\u306b\u64cd\u4f5c\uff08PHP 7+\uff09<\/td><td>Null\u5408\u4f53\u6f14\u7b97\u5b50<\/td><td><code>$value = $array['key1']['key2'] ?? null;<\/code><\/td><\/tr><tr><td>\u591a\u6b21\u5143\u914d\u5217\u3092\u5b89\u5168\u306b\u64cd\u4f5c\uff08PHP 8+\uff09<\/td><td>Nullsafe\u6f14\u7b97\u5b50<\/td><td><code>$value = $array['key1']?-&gt;key2;<\/code> \uff08\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u5834\u5408\uff09<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h4 class=\"wp-block-heading\" id=\"i-120\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u64cd\u4f5c<\/h4>\n\n\n<div id=\"id-15cac97d-0481-42e2-8842-078d5723ebef\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cNULL\u304b<\/td><td><code>is_null()<\/code> \u307e\u305f\u306f <code>=== null<\/code><\/td><td><code>if (is_null($obj)) { ... }<\/code><\/td><\/tr><tr><td>\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3059\u308b\u304b<\/td><td><code>property_exists()<\/code><\/td><td><code>if (property_exists($obj, 'prop')) { ... }<\/code><\/td><\/tr><tr><td>\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3057\u3001NULL\u3067\u306a\u3044\u304b<\/td><td><code>isset()<\/code><\/td><td><code>if (isset($obj-&gt;prop)) { ... }<\/code><\/td><\/tr><tr><td>\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u304cNULL\u304b<\/td><td><code>is_null()<\/code><\/td><td><code>if (is_null($obj-&gt;getProperty())) { ... }<\/code><\/td><\/tr><tr><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30c1\u30a7\u30fc\u30f3\u306e\u5b89\u5168\u306a\u64cd\u4f5c\uff08PHP 8+\uff09<\/td><td>Nullsafe\u6f14\u7b97\u5b50<\/td><td><code>$value = $obj?-&gt;prop?-&gt;method();<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h4 class=\"wp-block-heading\" id=\"i-121\">\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c<\/h4>\n\n\n<div id=\"id-3ddbfdcc-f4fa-48cd-bb8b-26bc513f0ddb\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>DB\u7d50\u679c\u304cNULL\u304b<\/td><td><code>is_null()<\/code><\/td><td><code>if (is_null($result)) { ... }<\/code><\/td><\/tr><tr><td>DB\u5217\u306e\u5024\u304cNULL\u304b<\/td><td><code>is_null()<\/code><\/td><td><code>if (is_null($row['column'])) { ... }<\/code><\/td><\/tr><tr><td>NULL\u3092\u8a31\u5bb9\u3059\u308b\u30d1\u30e9\u30e1\u30fc\u30bf<\/td><td>\u578b\u5ba3\u8a00\u3068<code>is_null()<\/code><\/td><td><code>function process(?string $param) { if (is_null($param)) { ... } }<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h4 class=\"wp-block-heading\" id=\"i-122\">API\u30fbJSON\u30c7\u30fc\u30bf<\/h4>\n\n\n<div id=\"id-1da1a32d-0bdd-4abe-9f1e-2392d96b13ea\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>JSON\u30ad\u30fc\u304c\u5b58\u5728\u3057\u3001NULL\u3067\u306a\u3044\u304b<\/td><td><code>isset()<\/code><\/td><td><code>if (isset($data['key'])) { ... }<\/code><\/td><\/tr><tr><td>JSON\u30c7\u30fc\u30bf\u3067NULL\u5024\u3092\u6271\u3046<\/td><td><code>is_null()<\/code><\/td><td><code>if (is_null($data['optional'])) { ... }<\/code><\/td><\/tr><tr><td>\u5b89\u5168\u306aJSON\u5024\u53d6\u5f97\uff08PHP 7+\uff09<\/td><td>Null\u5408\u4f53\u6f14\u7b97\u5b50<\/td><td><code>$value = $data['key'] ?? null;<\/code><\/td><\/tr><tr><td>JSON\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u5b89\u5168\u306a\u51e6\u7406<\/td><td>\u591a\u6bb5\u968e\u30c1\u30a7\u30c3\u30af<\/td><td><code>$status = isset($response['meta']) &amp;&amp; isset($response['meta']['status']) ? $response['meta']['status'] : null;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h4 class=\"wp-block-heading\" id=\"i-123\">PHP 7\u4ee5\u964d\u306e\u6700\u65b0\u30c6\u30af\u30cb\u30c3\u30af<\/h4>\n\n\n<div id=\"id-cc06ffa3-edcf-40ce-935c-f72d26a15669\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u78ba\u8a8d\u3057\u305f\u3044\u3053\u3068<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>\u5909\u6570\u304cNULL\u306e\u5834\u5408\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528<\/td><td>Null\u5408\u4f53\u6f14\u7b97\u5b50<\/td><td><code>$name = $user-&gt;name ?? '\u30b2\u30b9\u30c8';<\/code><\/td><\/tr><tr><td>\u8907\u6570\u5019\u88dc\u304b\u3089\u6700\u521d\u306e\u975eNULL\u5024\u3092\u4f7f\u7528<\/td><td>\u9023\u9396Null\u5408\u4f53\u6f14\u7b97\u5b50<\/td><td><code>$display = $user-&gt;nickname ?? $user-&gt;name ?? $user-&gt;email ?? '\u30b2\u30b9\u30c8';<\/code><\/td><\/tr><tr><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cNULL\u3067\u3082\u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9<\/td><td>Nullsafe\u6f14\u7b97\u5b50<\/td><td><code>$city = $user?-&gt;address?-&gt;city;<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<p>\u3053\u306e\u30c1\u30fc\u30c8\u30b7\u30fc\u30c8\u3092\u53c2\u8003\u306b\u3001\u30b3\u30fc\u30c9\u306e\u6587\u8108\u3084\u8981\u4ef6\u306b\u6700\u9069\u306anull\u5224\u5b9a\u65b9\u6cd5\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u9069\u5207\u306a\u65b9\u6cd5\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u5805\u7262\u6027\u3001\u53ef\u8aad\u6027\u3001\u4fdd\u5b88\u6027\u304c\u5411\u4e0a\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-124\">is_null\u95a2\u6570\u3092\u4f7f\u3063\u305f\u5805\u7262\u306a\u30b3\u30fc\u30c9\u4f5c\u6210\u306e\u30dd\u30a4\u30f3\u30c8<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u3092\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3057\u3001\u5805\u7262\u306aPHP\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u305f\u3081\u306e\u30dd\u30a4\u30f3\u30c8\u3092\u4ee5\u4e0b\u306b\u307e\u3068\u3081\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u539f\u5247\u3092\u5b88\u308b\u3053\u3068\u3067\u3001\u30d0\u30b0\u306e\u5c11\u306a\u3044\u5b89\u5b9a\u3057\u305f\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u958b\u767a\u3067\u304d\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-125\">1. \u65e9\u671f\u30ea\u30bf\u30fc\u30f3\u30d1\u30bf\u30fc\u30f3\u306e\u6d3b\u7528<\/h4>\n\n\n\n<p>NULL\u5024\u306e\u30c1\u30a7\u30c3\u30af\u306f\u3001\u95a2\u6570\u3084\u30e1\u30bd\u30c3\u30c9\u306e\u65e9\u3044\u6bb5\u968e\u3067\u884c\u3044\u3001\u6761\u4ef6\u5206\u5c90\u3092\u30b7\u30f3\u30d7\u30eb\u306b\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">function processUser($user) {\n    \/\/ \u65e9\u671f\u306bNULL\u30c1\u30a7\u30c3\u30af\n    if (is_null($user)) {\n        return null; \/\/ \u307e\u305f\u306f\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\n    }\n    \n    \/\/ \u4ee5\u964d\u306f$user\u304cNULL\u3067\u306a\u3044\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u3066\u3044\u308b\n    $name = $user-&gt;name;\n    $email = $user-&gt;email;\n    \/\/ ... \u51e6\u7406\u306e\u7d9a\u304d\n}\n<\/pre>\n\n\n\n<p>\u3053\u306e\u30d1\u30bf\u30fc\u30f3\u306f\u3001\u30cd\u30b9\u30c8\u3057\u305f\u6761\u4ef6\u5206\u5c90\u3092\u6e1b\u3089\u3057\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3092\u5411\u4e0a\u3055\u305b\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-126\">2. \u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u5b9f\u8df5<\/h4>\n\n\n\n<p>\u5916\u90e8\u304b\u3089\u306e\u30c7\u30fc\u30bf\u306f\u5e38\u306b\u7591\u3063\u3066\u304b\u304b\u308a\u3001\u9069\u5207\u306bNULL\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3044\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">function saveUserData($userData) {\n    \/\/ \u30c7\u30fc\u30bf\u306e\u5b58\u5728\u3068\u578b\u3092\u30c1\u30a7\u30c3\u30af\n    if (is_null($userData) || !is_array($userData)) {\n        throw new InvalidArgumentException('\u6709\u52b9\u306a\u30e6\u30fc\u30b6\u30fc\u30c7\u30fc\u30bf\u304c\u63d0\u4f9b\u3055\u308c\u3066\u3044\u307e\u305b\u3093');\n    }\n    \n    \/\/ \u5fc5\u9808\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u5b58\u5728\u30c1\u30a7\u30c3\u30af\n    $requiredFields = ['name', 'email'];\n    foreach ($requiredFields as $field) {\n        if (!isset($userData[$field]) || is_null($userData[$field])) {\n            throw new InvalidArgumentException(\"{$field}\u306f\u5fc5\u9808\u30d5\u30a3\u30fc\u30eb\u30c9\u3067\u3059\");\n        }\n    }\n    \n    \/\/ \u691c\u8a3c\u6e08\u307f\u306e\u30c7\u30fc\u30bf\u3067\u51e6\u7406\u3092\u7d9a\u884c\n    \/\/ ...\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-127\">3. \u660e\u793a\u7684\u306aNULL\u51e6\u7406\u306e\u5b9f\u88c5<\/h4>\n\n\n\n<p>NULL\u5024\u3092\u898b\u3064\u3051\u305f\u3068\u304d\u306e\u52d5\u4f5c\u3092\u660e\u793a\u7684\u306b\u5b9a\u7fa9\u3057\u3001\u4e88\u671f\u305b\u306c\u30a8\u30e9\u30fc\u3092\u9632\u304e\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">function calculateTotal($items) {\n    if (is_null($items)) {\n        return 0; \/\/ NULL\u306e\u5834\u5408\u306f\u660e\u793a\u7684\u306b0\u3092\u8fd4\u3059\n    }\n    \n    $total = 0;\n    foreach ($items as $item) {\n        \/\/ \u5404\u9805\u76ee\u3082\u5b89\u5168\u306b\u30c1\u30a7\u30c3\u30af\n        $price = is_null($item-&gt;price) ? 0 : $item-&gt;price;\n        $quantity = is_null($item-&gt;quantity) ? 1 : $item-&gt;quantity;\n        \n        $total += $price * $quantity;\n    }\n    \n    return $total;\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-128\">4. \u30c9\u30ad\u30e5\u30e1\u30f3\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u5145\u5b9f<\/h4>\n\n\n\n<p>\u95a2\u6570\u3084\u30e1\u30bd\u30c3\u30c9\u304cNULL\u5024\u3092\u3069\u3046\u6271\u3046\u304b\u3092\u660e\u78ba\u306b\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u5316\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/**\n * \u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u3092\u53d6\u5f97\u3059\u308b\n *\n * @param int|null $userId \u30e6\u30fc\u30b6\u30fcID\uff08null\u306e\u5834\u5408\u306f\u73fe\u5728\u306e\u30e6\u30fc\u30b6\u30fc\uff09\n * @return array|null \u30e6\u30fc\u30b6\u30fc\u60c5\u5831\u306e\u914d\u5217\u3001\u898b\u3064\u304b\u3089\u306a\u3044\u5834\u5408\u306fnull\n *\/\nfunction getUserInfo(?int $userId = null) {\n    \/\/ ...\n}\n<\/pre>\n\n\n\n<p>PHPDoc\u30b3\u30e1\u30f3\u30c8\u3092\u4f7f\u7528\u3057\u3066\u3001NULL\u5024\u306e\u6271\u3044\u3092\u660e\u78ba\u306b\u793a\u3059\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u5229\u7528\u8005\u304c\u3088\u308a\u5b89\u5168\u306b\u30b3\u30fc\u30c9\u3092\u4f7f\u3048\u307e\u3059\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-129\">5. \u4e00\u8cab\u3057\u305fNULL\u30c1\u30a7\u30c3\u30af\u30d1\u30bf\u30fc\u30f3\u306e\u63a1\u7528<\/h4>\n\n\n\n<p>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u3067\u4e00\u8cab\u3057\u305fNULL\u30c1\u30a7\u30c3\u30af\u30d1\u30bf\u30fc\u30f3\u3092\u63a1\u7528\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u3067\u4e00\u8cab\u3057\u305f\u30d1\u30bf\u30fc\u30f3\nclass BaseValidator {\n    protected function validateNotNull($value, $fieldName) {\n        if (is_null($value)) {\n            throw new ValidationException(\"{$fieldName}\u306fNULL\u3067\u3042\u3063\u3066\u306f\u306a\u308a\u307e\u305b\u3093\");\n        }\n    }\n    \n    \/\/ \u4ed6\u306e\u691c\u8a3c\u30e1\u30bd\u30c3\u30c9...\n}\n\n\/\/ \u7d99\u627f\u3057\u3066\u4f7f\u7528\nclass UserValidator extends BaseValidator {\n    public function validate($user) {\n        $this-&gt;validateNotNull($user, 'user');\n        $this-&gt;validateNotNull($user-&gt;name, 'name');\n        \/\/ ...\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-130\">6. \u30c6\u30b9\u30c8\u30b1\u30fc\u30b9\u3067\u306eNULL\u5024\u306e\u8003\u616e<\/h4>\n\n\n\n<p>\u30c6\u30b9\u30c8\u3067\u306f\u3001NULL\u5024\u3092\u542b\u3080\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u7a4d\u6975\u7684\u306b\u30c6\u30b9\u30c8\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public function testProcessUserWithNull() {\n    \/\/ NULL\u3092\u6e21\u3057\u305f\u3068\u304d\u306e\u52d5\u4f5c\u3092\u30c6\u30b9\u30c8\n    $result = $this-&gt;userService-&gt;processUser(null);\n    $this-&gt;assertNull($result);\n}\n\npublic function testProcessUserWithNullProperties() {\n    \/\/ \u30d7\u30ed\u30d1\u30c6\u30a3\u304cNULL\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30c6\u30b9\u30c8\n    $user = new User();\n    $user-&gt;name = null;\n    $user-&gt;email = 'test@example.com';\n    \n    $result = $this-&gt;userService-&gt;processUser($user);\n    $this-&gt;assertEquals('Unknown User', $result-&gt;displayName);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-131\">7. PHP 7\/8\u306e\u65b0\u6a5f\u80fd\u3092\u6d3b\u7528<\/h4>\n\n\n\n<p>\u30e2\u30c0\u30f3PHP\u306e\u6a5f\u80fd\u3092\u6d3b\u7528\u3057\u3066\u3001\u3088\u308a\u30af\u30ea\u30fc\u30f3\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7.1: Null\u8a31\u5bb9\u578b\u3068Null\u5408\u4f53\u6f14\u7b97\u5b50\nfunction getUserName(?User $user): string {\n    return $user?-&gt;name ?? '\u30b2\u30b9\u30c8';\n}\n\n\/\/ PHP 8.0: Nullsafe\u6f14\u7b97\u5b50\u3068Union Types\nfunction processAddress(User|null $user): string {\n    return $user?-&gt;address?-&gt;format() ?? '\u4f4f\u6240\u672a\u767b\u9332';\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-132\">8. \u4f8b\u5916\u3067\u306f\u306a\u304f\u7279\u6b8a\u5024\u3092\u8fd4\u3059\u5834\u5408\u306e\u6ce8\u610f<\/h4>\n\n\n\n<p>NULL\u5024\u3092\u7279\u6b8a\u306a\u30b1\u30fc\u30b9\u3068\u3057\u3066\u8fd4\u3059\u5834\u5408\u306f\u3001\u305d\u306e\u610f\u5473\u3092\u660e\u78ba\u306b\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/**\n * \u30e6\u30fc\u30b6\u30fc\u3092\u691c\u7d22\u3059\u308b\n *\n * @param string $query \u691c\u7d22\u30af\u30a8\u30ea\n * @return array|null \u691c\u7d22\u7d50\u679c\u3002\u7d50\u679c\u304c\u306a\u3044\u5834\u5408\u306f\u7a7a\u914d\u5217\u3001\u691c\u7d22\u5931\u6557\u6642\u306fnull\n *\/\nfunction searchUsers($query) {\n    try {\n        $results = $db-&gt;search($query);\n        return $results ?: []; \/\/ \u7d50\u679c\u304c\u306a\u3044\u5834\u5408\u306f\u7a7a\u914d\u5217\n    } catch (Exception $e) {\n        logError($e);\n        return null; \/\/ \u30a8\u30e9\u30fc\u6642\u306fnull\u3092\u8fd4\u3059\n    }\n}\n\n\/\/ \u547c\u3073\u51fa\u3057\u5074\n$results = searchUsers($query);\nif (is_null($results)) {\n    echo \"\u691c\u7d22\u4e2d\u306b\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u307e\u3057\u305f\";\n} else if (empty($results)) {\n    echo \"\u691c\u7d22\u7d50\u679c\u306f\u3042\u308a\u307e\u305b\u3093\";\n} else {\n    \/\/ \u7d50\u679c\u3092\u8868\u793a\n}\n<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u30dd\u30a4\u30f3\u30c8\u3092\u5b9f\u8df5\u3059\u308b\u3053\u3068\u3067\u3001<code>is_null()<\/code>\u95a2\u6570\u3092\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3057\u305f\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u4f5c\u6210\u3067\u304d\u307e\u3059\u3002\u7279\u306b\u30e2\u30c0\u30f3PHP\u306e\u6a5f\u80fd\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u7c21\u6f54\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u306b\u306a\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-133\">\u30af\u30ea\u30fc\u30f3\u30b3\u30fc\u30c9\u306b\u5411\u3051\u305f\u6b21\u306e\u30b9\u30c6\u30c3\u30d7<\/h3>\n\n\n\n<p><code>is_null()<\/code>\u95a2\u6570\u3068null\u5024\u306e\u9069\u5207\u306a\u6271\u3044\u3092\u7406\u89e3\u3057\u305f\u3068\u3053\u308d\u3067\u3001\u3088\u308a\u9ad8\u54c1\u8cea\u306aPHP\u30b3\u30fc\u30c9\u4f5c\u6210\u306b\u5411\u3051\u305f\u6b21\u306e\u30b9\u30c6\u30c3\u30d7\u3092\u3054\u7d39\u4ecb\u3057\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u8003\u3048\u65b9\u3084\u30c6\u30af\u30cb\u30c3\u30af\u3092\u53d6\u308a\u5165\u308c\u308b\u3053\u3068\u3067\u3001\u3042\u306a\u305f\u306e\u30b3\u30fc\u30c9\u306f\u3055\u3089\u306b\u6d17\u7df4\u3055\u308c\u305f\u3082\u306e\u306b\u306a\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-134\">1. NULL \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3\u306e\u5c0e\u5165<\/h4>\n\n\n\n<p>NULL\u5024\u306e\u30c1\u30a7\u30c3\u30af\u304c\u591a\u3044\u30b3\u30fc\u30c9\u306f\u3001Null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3\u3092\u4f7f\u3063\u3066\u7c21\u6f54\u306b\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5f93\u6765\u306e\u65b9\u6cd5\nif (is_null($logger)) {\n    \/\/ \u30ed\u30b0\u306a\u3057\u3067\u51e6\u7406\n} else {\n    $logger-&gt;info(\"\u51e6\u7406\u3092\u958b\u59cb\u3057\u307e\u3059\");\n}\n\n\/\/ NULL \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3\ninterface Logger {\n    public function info($message);\n    public function error($message);\n}\n\nclass ConsoleLogger implements Logger {\n    public function info($message) {\n        echo \"[INFO] $message\\n\";\n    }\n    \n    public function error($message) {\n        echo \"[ERROR] $message\\n\";\n    }\n}\n\nclass NullLogger implements Logger {\n    public function info($message) {\n        \/\/ \u4f55\u3082\u3057\u306a\u3044\n    }\n    \n    public function error($message) {\n        \/\/ \u4f55\u3082\u3057\u306a\u3044\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nfunction process(Logger $logger = null) {\n    $logger = $logger ?? new NullLogger();\n    $logger-&gt;info(\"\u51e6\u7406\u3092\u958b\u59cb\u3057\u307e\u3059\"); \/\/ \u5e38\u306b\u5b89\u5168\u306b\u547c\u3073\u51fa\u305b\u308b\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-135\">2. \u578b\u99c6\u52d5\u958b\u767a\u306e\u63a1\u7528<\/h4>\n\n\n\n<p>PHP 7.4\u4ee5\u964d\u306eTyped Properties\u30688.0\u306eUnion Types\u3092\u6d3b\u7528\u3057\u305f\u578b\u99c6\u52d5\u958b\u767a\u3092\u691c\u8a0e\u3057\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User {\n    public function __construct(\n        public string $name,\n        public string $email,\n        public ?string $phone = null,\n        public ?Address $address = null\n    ) {}\n}\n\nclass Address {\n    public function __construct(\n        public string $city,\n        public string $street,\n        public ?string $building = null\n    ) {}\n    \n    public function format(): string {\n        $result = \"{$this-&gt;city}, {$this-&gt;street}\";\n        if (!is_null($this-&gt;building)) {\n            $result .= \", {$this-&gt;building}\";\n        }\n        return $result;\n    }\n}\n\n\/\/ \u578b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\nfunction sendWelcomeEmail(User $user): void {\n    \/\/ $user\u304cnull\u3067\u306a\u3044\u3053\u3068\u304c\u578b\u30b7\u30b9\u30c6\u30e0\u306b\u3088\u3063\u3066\u4fdd\u8a3c\u3055\u308c\u308b\n    $emailService-&gt;send($user-&gt;email, \"\u3088\u3046\u3053\u305d{$user-&gt;name}\u3055\u3093\");\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-136\">3. \u4f8b\u5916\u306e\u9069\u5207\u306a\u6d3b\u7528<\/h4>\n\n\n\n<p>NULL\u5024\u304c\u4e88\u671f\u305b\u306c\u72b6\u614b\u3092\u8868\u3059\u5834\u5408\u306f\u3001\u9069\u5207\u306a\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\u3057\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">function findUserById(int $id): User {\n    $user = $this-&gt;repository-&gt;find($id);\n    \n    if (is_null($user)) {\n        throw new UserNotFoundException(\"ID: {$id} \u306e\u30e6\u30fc\u30b6\u30fc\u306f\u898b\u3064\u304b\u308a\u307e\u305b\u3093\u3067\u3057\u305f\");\n    }\n    \n    return $user;\n}\n\n\/\/ \u547c\u3073\u51fa\u3057\u5074\ntry {\n    $user = $this-&gt;findUserById($id);\n    \/\/ $user\u304cnull\u3067\u306a\u3044\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u3066\u3044\u308b\n    $this-&gt;processUser($user);\n} catch (UserNotFoundException $e) {\n    \/\/ \u30e6\u30fc\u30b6\u30fc\u304c\u898b\u3064\u304b\u3089\u306a\u3044\u5834\u5408\u306e\u660e\u793a\u7684\u306a\u51e6\u7406\n    $this-&gt;handleMissingUser($id);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-137\">4. \u5024\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u6d3b\u7528<\/h4>\n\n\n\n<p>NULL\u5024\u304c\u591a\u3044\u5834\u6240\u3067\u306f\u3001\u5024\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f7f\u3063\u3066\u3088\u308a\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u306b\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5f93\u6765\u306e\u65b9\u6cd5\uff08NULL\u5024\u3092\u4f7f\u7528\uff09\nclass User {\n    public ?string $phone = null;\n}\n\n\/\/ \u5024\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f7f\u3063\u305f\u65b9\u6cd5\nclass PhoneNumber {\n    private string $number;\n    \n    public function __construct(string $number) {\n        \/\/ \u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\n        if (!preg_match('\/^\\d{10,11}$\/', $number)) {\n            throw new InvalidArgumentException('\u7121\u52b9\u306a\u96fb\u8a71\u756a\u53f7\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3067\u3059');\n        }\n        $this-&gt;number = $number;\n    }\n    \n    public function format(): string {\n        \/\/ \u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u51e6\u7406\n        return $this-&gt;number;\n    }\n}\n\nclass User {\n    private ?PhoneNumber $phone = null;\n    \n    public function setPhone(?string $phoneNumber): void {\n        if (is_null($phoneNumber)) {\n            $this-&gt;phone = null;\n            return;\n        }\n        \n        $this-&gt;phone = new PhoneNumber($phoneNumber);\n    }\n    \n    public function hasPhone(): bool {\n        return !is_null($this-&gt;phone);\n    }\n    \n    public function getFormattedPhone(): string {\n        return $this-&gt;hasPhone() ? $this-&gt;phone-&gt;format() : '\u672a\u767b\u9332';\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-138\">5. \u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30a2\u30d7\u30ed\u30fc\u30c1\u306e\u63a1\u7528<\/h4>\n\n\n\n<p>NULL\u5024\u306e\u6271\u3044\u3092\u6539\u5584\u3059\u308b\u305f\u3081\u306b\u3001\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u8003\u3048\u65b9\u3092\u53d6\u308a\u5165\u308c\u308b\u3053\u3068\u3082\u691c\u8a0e\u3057\u3066\u304f\u3060\u3055\u3044\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ Optional\u30d1\u30bf\u30fc\u30f3\u306e\u7c21\u6613\u5b9f\u88c5\nclass Optional {\n    private $value;\n    \n    private function __construct($value) {\n        $this-&gt;value = $value;\n    }\n    \n    public static function of($value): self {\n        return new self($value);\n    }\n    \n    public static function empty(): self {\n        return new self(null);\n    }\n    \n    public function isPresent(): bool {\n        return !is_null($this-&gt;value);\n    }\n    \n    public function get() {\n        if (is_null($this-&gt;value)) {\n            throw new RuntimeException(\"\u5024\u304c\u5b58\u5728\u3057\u307e\u305b\u3093\");\n        }\n        return $this-&gt;value;\n    }\n    \n    public function orElse($other) {\n        return is_null($this-&gt;value) ? $other : $this-&gt;value;\n    }\n    \n    public function map(callable $mapper): self {\n        if (is_null($this-&gt;value)) {\n            return self::empty();\n        }\n        return self::of($mapper($this-&gt;value));\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nfunction findUser($id): Optional {\n    $user = $repository-&gt;find($id);\n    return is_null($user) ? Optional::empty() : Optional::of($user);\n}\n\n\/\/ \u30c1\u30a7\u30fc\u30f3\u306b\u3088\u308b\u5b89\u5168\u306a\u51e6\u7406\n$greeting = findUser($id)\n    -&gt;map(fn($user) =&gt; $user-&gt;getName())\n    -&gt;orElse(\"\u30b2\u30b9\u30c8\");\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-139\">6. \u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\u306e\u5c0e\u5165<\/h4>\n\n\n\n<p>\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u3092\u5411\u4e0a\u3055\u305b\u308b\u305f\u3081\u306b\u3001\u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\u3092\u5c0e\u5165\u3057\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>PHPStan<\/strong>: NULL\u5024\u306e\u4e0d\u9069\u5207\u306a\u4f7f\u7528\u3084\u672a\u5b9a\u7fa9\u5909\u6570\u306e\u691c\u51fa\u306b\u512a\u308c\u3066\u3044\u307e\u3059<\/li>\n\n\n\n<li><strong>Psalm<\/strong>: \u3088\u308a\u53b3\u683c\u306a\u578b\u30c1\u30a7\u30c3\u30af\u3068NULL\u5b89\u5168\u6027\u306e\u691c\u8a3c\u304c\u3067\u304d\u307e\u3059<\/li>\n\n\n\n<li><strong>PHP_CodeSniffer<\/strong>: \u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u898f\u7d04\u306e\u9075\u5b88\u72b6\u6cc1\u3092\u30c1\u30a7\u30c3\u30af\u3067\u304d\u307e\u3059<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># PHPStan\u306e\u30a4\u30f3\u30b9\u30c8\u30fc\u30eb\u3068\u5b9f\u884c\u4f8b\ncomposer require --dev phpstan\/phpstan\n.\/vendor\/bin\/phpstan analyse src tests --level=7\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-140\">7. \u30c7\u30b6\u30a4\u30f3\u30d1\u30bf\u30fc\u30f3\u306e\u6d3b\u7528<\/h4>\n\n\n\n<p>NULL\u306e\u6271\u3044\u3092\u6539\u5584\u3059\u308b\u30c7\u30b6\u30a4\u30f3\u30d1\u30bf\u30fc\u30f3\u3092\u691c\u8a0e\u3057\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u30cc\u30eb\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3<\/strong>: \u524d\u8ff0\u306e\u901a\u308a\u3001NULL\u5024\u306e\u4ee3\u308f\u308a\u306b\u7279\u6b8a\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f7f\u7528<\/li>\n\n\n\n<li><strong>\u30d3\u30eb\u30c0\u30fc\u30d1\u30bf\u30fc\u30f3<\/strong>: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u69cb\u7bc9\u6642\u306bNULL\u5024\u3092\u9069\u5207\u306b\u51e6\u7406<\/li>\n\n\n\n<li><strong>\u30d5\u30a1\u30af\u30c8\u30ea\u30fc\u30d1\u30bf\u30fc\u30f3<\/strong>: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u751f\u6210\u6642\u306eNULL\u5024\u306e\u6271\u3044\u3092\u96c6\u7d04<\/li>\n\n\n\n<li><strong>\u6226\u7565\u30d1\u30bf\u30fc\u30f3<\/strong>: NULL\u5024\u306b\u5bfe\u3059\u308b\u7570\u306a\u308b\u51e6\u7406\u6226\u7565\u3092\u5207\u308a\u66ff\u3048\u53ef\u80fd\u306b<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-141\">8. \u30c6\u30b9\u30c8\u306e\u5145\u5b9f<\/h4>\n\n\n\n<p>NULL\u5024\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u30c6\u30b9\u30c8\u3092\u5145\u5b9f\u3055\u305b\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHPUnit\u3067\u306eNULL\u5024\u30c6\u30b9\u30c8\u4f8b\npublic function testUserWithNullAddress() {\n    $user = new User('John', 'john@example.com');\n    $this-&gt;assertNull($user-&gt;getAddress());\n    $this-&gt;assertEquals('\u4f4f\u6240\u672a\u767b\u9332', $user-&gt;getFormattedAddress());\n}\n\npublic function testNullParameterHandling() {\n    \/\/ NULL\u5024\u3092\u6e21\u3057\u305f\u5834\u5408\u306e\u30c6\u30b9\u30c8\n    $result = $this-&gt;service-&gt;process(null);\n    $this-&gt;assertEquals('\u30c7\u30d5\u30a9\u30eb\u30c8\u5024', $result);\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-142\">9. \u30c1\u30fc\u30e0\u5185\u3067\u306e\u898f\u7d04\u78ba\u7acb<\/h4>\n\n\n\n<p>NULL\u5024\u306e\u6271\u3044\u306b\u3064\u3044\u3066\u30c1\u30fc\u30e0\u5185\u3067\u4e00\u8cab\u3057\u305f\u898f\u7d04\u3092\u8a2d\u3051\u308b\u3053\u3068\u3082\u91cd\u8981\u3067\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>NULL\u5024\u3092\u8fd4\u3059\u6761\u4ef6\uff08\u30a8\u30e9\u30fc\u6642\u3001\u8a72\u5f53\u306a\u3057\u6642\u306a\u3069\uff09\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n\n\n\n<li>NULL\u30c1\u30a7\u30c3\u30af\u306e\u65b9\u6cd5\uff08<code>is_null()<\/code>\u304b<code>=== null<\/code>\u304b\uff09\u3092\u7d71\u4e00\u3059\u308b<\/li>\n\n\n\n<li>\u5f15\u6570\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u6271\u3044\u3092\u7d71\u4e00\u3059\u308b<\/li>\n\n\n\n<li>NULL\u8a31\u5bb9\u578b\u306e\u4f7f\u7528\u65b9\u91dd\u3092\u6c7a\u3081\u308b<\/li>\n\n\n\n<li>\u4f8b\u5916\u3068NULL\u623b\u308a\u5024\u306e\u4f7f\u3044\u5206\u3051\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n<\/ul>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u6b21\u306e\u30b9\u30c6\u30c3\u30d7\u3092\u5b9f\u8df5\u3059\u308b\u3053\u3068\u3067\u3001\u5358\u306a\u308bNULL\u30c1\u30a7\u30c3\u30af\u4ee5\u4e0a\u306e\u3001\u3088\u308a\u6d17\u7df4\u3055\u308c\u305f\u30b3\u30fc\u30c9\u3078\u3068\u9032\u5316\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<code>is_null()<\/code>\u95a2\u6570\u3092\u9069\u5207\u306b\u4f7f\u3044\u3053\u306a\u3059\u3053\u3068\u306f\u3001PHP\u30a8\u30f3\u30b8\u30cb\u30a2\u3068\u3057\u3066\u306e\u6210\u9577\u306b\u304a\u3051\u308b\u91cd\u8981\u306a\u30de\u30a4\u30eb\u30b9\u30c8\u30fc\u30f3\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u308c\u304b\u3089\u3082\u30af\u30ea\u30fc\u30f3\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u76ee\u6307\u3057\u3066\u3001\u6280\u8853\u7814\u947d\u3092\u7d9a\u3051\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>PHP\u958b\u767a\u306b\u304a\u3044\u3066\u3001\u5909\u6570\u304cnull\u304b\u3069\u3046\u304b\u3092\u6b63\u78ba\u306b\u5224\u5b9a\u3059\u308b\u3053\u3068\u306f\u3001\u5b89\u5b9a\u3057\u305f\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u69cb\u7bc9\u306e\u57fa\u672c\u3067\u3059\u3002\u3057\u304b\u3057\u3001PHP\u306b\u306fis_null()\u3001isset()\u3001empty()\u3001\u305d\u3057\u3066\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08=== null\uff09\u306a\u3069\u3001\u4f3c &#8230; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,63],"tags":[],"class_list":{"0":"post-3764","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-php","7":"category-php-syntax","8":"nothumb"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3764","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3764"}],"version-history":[{"count":1,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3764\/revisions"}],"predecessor-version":[{"id":3767,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3764\/revisions\/3767"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3764"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3764"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3764"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}