{"id":3399,"date":"2025-03-24T08:46:17","date_gmt":"2025-03-23T23:46:17","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=3399"},"modified":"2025-03-24T08:46:48","modified_gmt":"2025-03-23T23:46:48","slug":"php%e3%81%aeempty%e9%96%a2%e6%95%b0%e3%83%9e%e3%82%b9%e3%82%bf%e3%83%bc%e3%82%ac%e3%82%a4%e3%83%89-%e5%9f%ba%e6%9c%ac%e3%81%8b%e3%82%89%e5%bf%9c%e7%94%a8%e3%81%be%e3%81%a77%e3%81%a4%e3%81%ae","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=3399","title":{"rendered":"PHP\u306eempty()\u95a2\u6570\u30de\u30b9\u30bf\u30fc\u30ac\u30a4\u30c9 -\u57fa\u672c\u304b\u3089\u5fdc\u7528\u307e\u30677\u3064\u306e\u5b9f\u8df5\u4f8b"},"content":{"rendered":"\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\">empty()\u95a2\u6570\u306e\u57fa\u790e\u77e5\u8b58 \u2013 PHP\u306e\u5909\u6570\u691c\u8a3c\u3092\u7406\u89e3\u3059\u308b<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">empty()\u95a2\u6570\u306e\u6b63\u78ba\u306a\u5b9a\u7fa9\u3068\u57fa\u672c\u69cb\u6587<\/a>      <\/li>      <li>        <a href=\"#i-2\">empty()\u304c\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3059\u308b8\u7a2e\u985e\u306e\u5024<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-3\">PHP 7\u30688\u3067\u306e\u52d5\u4f5c\u306e\u9055\u3044\u3068\u6ce8\u610f\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-4\">empty()\u3068\u4ed6\u306e\u691c\u8a3c\u95a2\u6570\u306e\u9055\u3044 \u2013 \u6b63\u3057\u3044\u4f7f\u3044\u65b9\u306e\u30b3\u30c4<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-5\">empty()\u3068isset()\u306e\u660e\u78ba\u306a\u9055\u3044\u3068\u4f7f\u7528\u30b7\u30fc\u30f3<\/a>      <\/li>      <li>        <a href=\"#i-6\">empty()\u3068is_null()\u3092\u6df7\u540c\u3057\u306a\u3044\u305f\u3081\u306e\u77e5\u8b58<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-7\">empty()\u3068!\u6f14\u7b97\u306e\u6bd4\u8f03 \u2013 \u3069\u3061\u3089\u304c\u6b63\u3057\u3044\u304b<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-8\">\u5b9f\u8df5\u4f8b1: \u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-9\">\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u691c\u8a3c\u3067empty()\u3092\u52b9\u679c\u7684\u306b\u4f7f\u3046\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-10\">\u3088\u304f\u3042\u308b\u5b9f\u88c5\u30df\u30b9\u3068\u305d\u306e\u56de\u907f\u7b56<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-11\">\u5b9f\u8df5\u4f8b2: \u914d\u5217\u3068\u9023\u60f3\u914d\u5217\u3067\u306e\u6d3b\u7528\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-12\">\u914d\u5217\u8981\u7d20\u306e\u5b58\u5728\u78ba\u8a8d\u3068empty()\u306e\u95a2\u4fc2<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-13\">\u591a\u6b21\u5143\u914d\u5217\u3067\u6ce8\u610f\u3059\u3079\u304d\u52d5\u4f5c<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-14\">\u5b9f\u8df5\u4f8b3: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u64cd\u4f5c\u306b\u304a\u3051\u308bempty()\u306e\u6319\u52d5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-15\">\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9__isset\u3068__empty\u306e\u5b9f\u88c5\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-16\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u691c\u8a3c\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-17\">\u5b9f\u8df5\u4f8b4: \u6761\u4ef6\u5206\u5c90\u3067\u306e\u52b9\u7387\u7684\u306a\u4f7f\u3044\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-18\">\u4e09\u9805\u6f14\u7b97\u5b50\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-19\">\u8907\u6570\u306e\u6761\u4ef6\u3092\u898b\u6975\u3081\u308b\u969b\u306e\u8ad6\u7406\u7684\u306a\u8003\u3048\u65b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-20\">\u5b9f\u8df5\u4f8b5: \u6570\u5024\u3068empty()\u306e\u610f\u5916\u306a\u95a2\u4fc2<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-21\">\u6570\u50240\u3068\u6587\u5b57\u5217\u201d0\u2033\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u66d6\u6627\u3055\u3092\u89e3\u6d88\u3059\u308b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-22\">\u6570\u5024\u691c\u8a3c\u306e\u6b63\u3057\u3044\u30a2\u30d7\u30ed\u30fc\u30c1<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-23\">\u5b9f\u8df5\u4f8b6: \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fempty()\u306e\u4f7f\u7528<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-24\">empty()\u306e\u5185\u90e8\u52d5\u4f5c\u3068\u30e1\u30e2\u30ea\u52b9\u7387<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-25\">\u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-26\">\u5b9f\u8df5\u4f8b7: \u30bb\u30ad\u30e5\u30a2\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3068empty()<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-27\">\u5916\u90e8\u5165\u529b\u30c7\u30fc\u30bf\u3092\u691c\u8a3c\u3059\u308b\u969b\u306e\u5b89\u5168\u5bfe\u7b56<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-28\">\u578b\u306e\u53b3\u5bc6\u306a\u691c\u8a3c\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u30ed\u30d0\u30b9\u30c8\u306a\u5b9f\u88c5\u4f8b<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-29\">empty()\u95a2\u6570\u3092\u4f7f\u3044\u3053\u306a\u3059\u305f\u3081\u306e7\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-30\">\u53ef\u8aad\u6027\u3092\u9ad8\u3081\u308b\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b9\u30bf\u30a4\u30eb<\/a>      <\/li>      <li>        <a href=\"#i-31\">\u30e6\u30cb\u30c3\u30c8\u30c6\u30b9\u30c8\u3067\u306eempty()\u306e\u30c6\u30b9\u30c8\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-32\">\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\u3068\u52b9\u679c\u7684\u306a\u4f75\u7528<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-33\">\u305d\u306e\u4ed6\u306e4\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/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\">empty()\u95a2\u6570\u306e\u57fa\u790e\u77e5\u8b58 \u2013 PHP\u306e\u5909\u6570\u691c\u8a3c\u3092\u7406\u89e3\u3059\u308b<\/h2>\n\n\n\n<p>PHP\u3067\u30a6\u30a7\u30d6\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u958b\u767a\u3059\u308b\u969b\u3001\u5909\u6570\u304c\u300c\u7a7a\u300d\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u306e\u691c\u8a3c\u306f\u975e\u5e38\u306b\u91cd\u8981\u306a\u30d7\u30ed\u30bb\u30b9\u3067\u3059\u3002\u7279\u306b\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u51e6\u7406\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u53d6\u5f97\u7d50\u679c\u3092\u6271\u3046\u5834\u5408\u3001\u9069\u5207\u306a\u691c\u8a3c\u304c\u884c\u308f\u308c\u3066\u3044\u306a\u3044\u3068\u30d0\u30b0\u3084\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u306e\u554f\u984c\u306b\u3064\u306a\u304c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u3053\u3067\u5f79\u7acb\u3064\u306e\u304cPHP\u306e<code>empty()<\/code>\u95a2\u6570\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-1\">empty()\u95a2\u6570\u306e\u6b63\u78ba\u306a\u5b9a\u7fa9\u3068\u57fa\u672c\u69cb\u6587<\/h3>\n\n\n\n<p><code>empty()<\/code>\u95a2\u6570\u306f\u3001\u5909\u6570\u304c\u300c\u7a7a\u300d\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u691c\u8a3c\u3059\u308b\u305f\u3081\u306e\u7d44\u307f\u8fbc\u307f\u95a2\u6570\u3067\u3059\u3002\u3053\u306e\u95a2\u6570\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\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 empty(mixed $var)\n<\/pre>\n\n\n\n<p>\u3053\u306e\u95a2\u6570\u306f\u3001\u5f15\u6570\u3068\u3057\u3066\u6e21\u3055\u308c\u305f\u5909\u6570\u304c\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u308b\u5834\u5408\u306b<code>true<\/code>\u3092\u8fd4\u3057\u3001\u305d\u3046\u3067\u306a\u3044\u5834\u5408\u306f<code>false<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002PHP 5.5.0\u4ee5\u964d\u3067\u306f\u3001\u5909\u6570\u3060\u3051\u3067\u306a\u304f\u5f0f\u3082\u5f15\u6570\u3068\u3057\u3066\u6e21\u3059\u3053\u3068\u304c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\n$name = '';\nif (empty($name)) {\n    echo \"\u540d\u524d\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u305b\u3093\"; \/\/ \u3053\u306e\u884c\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n\n\/\/ PHP 5.5.0\u4ee5\u964d\u306e\u5f0f\u3092\u4f7f\u3063\u305f\u4f8b\n$users = ['user1', 'user2'];\nif (empty($users[2])) {\n    echo \"\u6307\u5b9a\u3055\u308c\u305f\u30e6\u30fc\u30b6\u30fc\u306f\u5b58\u5728\u3057\u307e\u305b\u3093\"; \/\/ \u3053\u306e\u884c\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n<\/pre>\n\n\n\n<p>\u91cd\u8981\u306a\u306e\u306f\u3001<code>empty()<\/code>\u306f\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066\u3082\u5b89\u5168\u306b\u4f7f\u7528\u3067\u304d\u308b\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002\u5909\u6570\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u3067\u3082\u3001\u30a8\u30e9\u30fc\u306f\u767a\u751f\u305b\u305a\u3001\u5358\u306b<code>true<\/code>\u304c\u8fd4\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-2\">empty()\u304c\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3059\u308b8\u7a2e\u985e\u306e\u5024<\/h3>\n\n\n\n<p><code>empty()<\/code>\u95a2\u6570\u306f\u4ee5\u4e0b\u306e8\u7a2e\u985e\u306e\u5024\u3092\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3057\u307e\u3059\uff1a<\/p>\n\n\n<div id=\"id-15eedb2e-97ad-4f24-95ac-199fbd5d3312\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u5024<\/th><th>\u4f8b<\/th><th>empty()\u306e\u7d50\u679c<\/th><\/tr><\/thead><tbody><tr><td>\u7a7a\u6587\u5b57\u5217<\/td><td><code>\"\"<\/code> \u307e\u305f\u306f <code>''<\/code><\/td><td>true<\/td><\/tr><tr><td>\u6574\u6570\u306e0<\/td><td><code>0<\/code><\/td><td>true<\/td><\/tr><tr><td>\u6d6e\u52d5\u5c0f\u6570\u70b9\u306e0<\/td><td><code>0.0<\/code><\/td><td>true<\/td><\/tr><tr><td>\u6587\u5b57\u5217\u306e\u201d0\u2033<\/td><td><code>\"0\"<\/code><\/td><td>true<\/td><\/tr><tr><td><code>null<\/code><\/td><td><code>null<\/code><\/td><td>true<\/td><\/tr><tr><td><code>false<\/code><\/td><td><code>false<\/code><\/td><td>true<\/td><\/tr><tr><td>\u7a7a\u306e\u914d\u5217<\/td><td><code>array()<\/code> \u307e\u305f\u306f <code>[]<\/code><\/td><td>true<\/td><\/tr><tr><td>\u672a\u5b9a\u7fa9\u306e\u5909\u6570<\/td><td>\u5ba3\u8a00\u3055\u308c\u3066\u3044\u306a\u3044\u5909\u6570<\/td><td>true<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<p>\u3053\u308c\u3089\u306e\u5024\u4ee5\u5916\u306f\u5168\u3066\u300c\u7a7a\u3067\u306f\u306a\u3044\u300d\u3068\u5224\u65ad\u3055\u308c\u3001<code>false<\/code>\u304c\u8fd4\u3055\u308c\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=\"\">\/\/ empty()\u306e\u5b9f\u969b\u306e\u6319\u52d5\u3092\u78ba\u8a8d\nvar_dump(empty(\"\"));         \/\/ bool(true)\nvar_dump(empty(0));          \/\/ bool(true)\nvar_dump(empty(0.0));        \/\/ bool(true)\nvar_dump(empty(\"0\"));        \/\/ bool(true)\nvar_dump(empty(null));       \/\/ bool(true)\nvar_dump(empty(false));      \/\/ bool(true)\nvar_dump(empty(array()));    \/\/ bool(true)\nvar_dump(empty($undefined)); \/\/ bool(true) - \u8b66\u544a\u306f\u767a\u751f\u3057\u306a\u3044\n\n\/\/ \u7a7a\u3067\u306f\u306a\u3044\u5024\u306e\u4f8b\nvar_dump(empty(1));          \/\/ bool(false)\nvar_dump(empty(\"text\"));     \/\/ bool(false)\nvar_dump(empty(\"0.0\"));      \/\/ bool(false) - \u6587\u5b57\u5217\"0.0\"\u306f\u7a7a\u3067\u306f\u306a\u3044\nvar_dump(empty(true));       \/\/ bool(false)\nvar_dump(empty([0]));        \/\/ bool(false) - \u7a7a\u3067\u306a\u3044\u914d\u5217\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-3\">PHP 7\u30688\u3067\u306e\u52d5\u4f5c\u306e\u9055\u3044\u3068\u6ce8\u610f\u70b9<\/h3>\n\n\n\n<p>PHP\u306e\u30d0\u30fc\u30b8\u30e7\u30f3\u306b\u3088\u3063\u3066\u3001<code>empty()<\/code>\u95a2\u6570\u306e\u6319\u52d5\u306b\u5fae\u5999\u306a\u9055\u3044\u304c\u3042\u308a\u307e\u3059\u3002\u7279\u306bPHP 7.4\u30688.0\u3067\u306f\u91cd\u8981\u306a\u5909\u66f4\u304c\u3042\u308a\u307e\u3057\u305f\u3002<\/p>\n\n\n\n<p><strong>PHP 7.4\u3067\u306e\u5909\u66f4\u70b9:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30ea\u30b9\u30c8\u4ee3\u5165\u3067\u306e<code>empty()<\/code>\u306e\u4f7f\u7528\u304c\u975e\u63a8\u5968\u3068\u306a\u308a\u307e\u3057\u305f\u3002 <code>\/\/ PHP 7.4\u3067\u975e\u63a8\u5968\u3068\u306a\u3063\u305f\u66f8\u304d\u65b9list($a, $b) = $array;if (empty($a)) { \/* ... *\/ } \/\/ \u554f\u984c\u306a\u3057\/\/ \u4ee3\u308f\u308a\u306b\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u66f8\u304f\u3053\u3068\u304c\u63a8\u5968[$a, $b] = $array;if (empty($a)) { \/* ... *\/ }<\/code><\/li>\n<\/ul>\n\n\n\n<p><strong>PHP 8.0\u3067\u306e\u5909\u66f4\u70b9:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5bfe\u3059\u308b<code>__isset()<\/code>\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u306e\u52d5\u4f5c\u304c\u5909\u66f4\u3055\u308c\u307e\u3057\u305f\u3002PHP 8.0\u3067\u306f\u3001<code>empty()<\/code>\u304c\u5185\u90e8\u7684\u306b<code>__isset()<\/code>\u3092\u547c\u3073\u51fa\u3059\u969b\u306e\u6319\u52d5\u304c\u3088\u308a\u53b3\u5bc6\u306b\u306a\u308a\u307e\u3057\u305f\u3002<\/li>\n\n\n\n<li>\u578b\u30b7\u30b9\u30c6\u30e0\u306e\u5f37\u5316\u306b\u3088\u308a\u3001\u578b\u306e\u53b3\u5bc6\u306a\u30c1\u30a7\u30c3\u30af\u304c\u884c\u308f\u308c\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u305f\u3081\u3001\u671f\u5f85\u901a\u308a\u306e\u7d50\u679c\u304c\u5f97\u3089\u308c\u306a\u3044\u5834\u5408\u304c\u3042\u308b\u306e\u3067\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/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=\"\">\/\/ PHP 8.0\u3067\u3088\u308a\u660e\u78ba\u306b\u306a\u3063\u305f__isset()\u3068__empty\u306e\u95a2\u4fc2\nclass User {\n    private $data = [];\n    \n    public function __isset($name) {\n        return isset($this-&gt;data[$name]);\n    }\n    \n    public function __get($name) {\n        return $this-&gt;data[$name] ?? null;\n    }\n}\n\n$user = new User();\n\/\/ PHP 8.0\u3067\u306f__isset()\u304c\u547c\u3073\u51fa\u3055\u308c\u305f\u5f8c\u3001\n\/\/ \u305d\u306e\u7d50\u679c\u304c\u771f\u306e\u5834\u5408\u306e\u307f__get()\u3067\u5024\u3092\u53d6\u5f97\u3057\u8a55\u4fa1\u3057\u307e\u3059\n<\/pre>\n\n\n\n<p>PHP\u306e\u30d0\u30fc\u30b8\u30e7\u30f3\u30a2\u30c3\u30d7\u30b0\u30ec\u30fc\u30c9\u3092\u884c\u3046\u969b\u306f\u3001\u3053\u308c\u3089\u306e\u5909\u66f4\u70b9\u306b\u6ce8\u610f\u3057\u3066\u3001\u65e2\u5b58\u306e\u30b3\u30fc\u30c9\u3092\u898b\u76f4\u3059\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u7279\u306b\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u3084CMS\u306e\u30ab\u30b9\u30bf\u30de\u30a4\u30ba\u3092\u884c\u3063\u3066\u3044\u308b\u5834\u5408\u3001\u3053\u308c\u3089\u306e\u9055\u3044\u306b\u3088\u3063\u3066\u4e88\u671f\u3057\u306a\u3044\u52d5\u4f5c\u304c\u767a\u751f\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-4\">empty()\u3068\u4ed6\u306e\u691c\u8a3c\u95a2\u6570\u306e\u9055\u3044 \u2013 \u6b63\u3057\u3044\u4f7f\u3044\u65b9\u306e\u30b3\u30c4<\/h2>\n\n\n\n<p>PHP\u306b\u306f\u5909\u6570\u306e\u72b6\u614b\u3092\u691c\u8a3c\u3059\u308b\u305f\u3081\u306e\u3044\u304f\u3064\u304b\u306e\u95a2\u6570\u304c\u7528\u610f\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u6b63\u3057\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u305f\u3081\u306b\u306f\u3001<code>empty()<\/code>\u3001<code>isset()<\/code>\u3001<code>is_null()<\/code>\u306a\u3069\u306e\u95a2\u6570\u306e\u9055\u3044\u3092\u7406\u89e3\u3057\u3001\u9069\u5207\u306a\u5834\u9762\u3067\u4f7f\u3044\u5206\u3051\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u3053\u306e\u77e5\u8b58\u304c\u306a\u3044\u3068\u3001\u4e88\u671f\u3057\u306a\u3044\u30d0\u30b0\u306e\u539f\u56e0\u306b\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-5\">empty()\u3068isset()\u306e\u660e\u78ba\u306a\u9055\u3044\u3068\u4f7f\u7528\u30b7\u30fc\u30f3<\/h3>\n\n\n\n<p><code>empty()<\/code>\u3068<code>isset()<\/code>\u306f\u6df7\u540c\u3055\u308c\u304c\u3061\u306a\u95a2\u6570\u3067\u3059\u304c\u3001\u305d\u306e\u76ee\u7684\u3068\u52d5\u4f5c\u306f\u5927\u304d\u304f\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p><strong>isset()\u306e\u7279\u5fb4:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5909\u6570\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u3066\u3001\u304b\u3064<code>null<\/code>\u3067\u306f\u306a\u3044\u3053\u3068\u3092\u78ba\u8a8d\u3059\u308b<\/li>\n\n\n\n<li>\u8907\u6570\u306e\u5909\u6570\u3092\u30c1\u30a7\u30c3\u30af\u3067\u304d\u308b\uff08\u3059\u3079\u3066\u304c\u6761\u4ef6\u3092\u6e80\u305f\u3059\u5834\u5408\u306e\u307f<code>true<\/code>\u3092\u8fd4\u3059\uff09<\/li>\n\n\n\n<li>\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066\u8b66\u544a\u3084\u30a8\u30e9\u30fc\u3092\u767a\u751f\u3055\u305b\u306a\u3044<\/li>\n\n\n\n<li>\u8a00\u8a9e\u69cb\u9020\uff08\u95a2\u6570\u3067\u306f\u306a\u3044\uff09\u306a\u306e\u3067\u3001\u975e\u5e38\u306b\u9ad8\u901f<\/li>\n<\/ul>\n\n\n\n<p><strong>empty()\u306e\u7279\u5fb4:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5909\u6570\u304c\u300c\u7a7a\u300d\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\uff08\u524d\u8ff0\u306e8\u7a2e\u985e\u306e\u300c\u7a7a\u300d\u306e\u5024\uff09<\/li>\n\n\n\n<li>\u5909\u6570\u304c\u672a\u5b9a\u7fa9\u3067\u3082\u8b66\u544a\u3084\u30a8\u30e9\u30fc\u3092\u767a\u751f\u3055\u305b\u306a\u3044<\/li>\n\n\n\n<li>\u5185\u90e8\u7684\u306b\u306f\u5909\u6570\u306e\u5b58\u5728\u78ba\u8a8d\uff08isset()\u76f8\u5f53\uff09\u3092\u884c\u3063\u3066\u304b\u3089\u5024\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b<\/li>\n\n\n\n<li>\u3053\u3061\u3089\u3082\u8a00\u8a9e\u69cb\u9020\u3067\u3042\u308a\u3001\u9ad8\u901f\u306b\u52d5\u4f5c\u3059\u308b<\/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=\"\">\/\/ isset()\u3068empty()\u306e\u9055\u3044\u3092\u793a\u3059\u4f8b\n$a = 0;\n$b = null;\n$c = '';\n\/\/ $d \u306f\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u306a\u3044\n\n\/\/ isset()\u306e\u7d50\u679c\nvar_dump(isset($a));  \/\/ bool(true) - \u5b9a\u7fa9\u6e08\u307f\u3067null\u3067\u306a\u3044\nvar_dump(isset($b));  \/\/ bool(false) - null\u306a\u306e\u3067false\nvar_dump(isset($c));  \/\/ bool(true) - \u5b9a\u7fa9\u6e08\u307f\u3067null\u3067\u306a\u3044\nvar_dump(isset($d));  \/\/ bool(false) - \u672a\u5b9a\u7fa9\u306a\u306e\u3067false\n\n\/\/ empty()\u306e\u7d50\u679c\nvar_dump(empty($a));  \/\/ bool(true) - 0\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($b));  \/\/ bool(true) - null\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($c));  \/\/ bool(true) - \u7a7a\u6587\u5b57\u5217\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($d));  \/\/ bool(true) - \u672a\u5b9a\u7fa9\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\n<\/pre>\n\n\n\n<p><strong>\u4f7f\u7528\u30b7\u30fc\u30f3:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>isset()<\/code>: \u5909\u6570\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\u306b\u6700\u9069\u3002\u7279\u306b\u914d\u5217\u306e\u30ad\u30fc\u3084\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3059\u308b\u304b\u306e\u78ba\u8a8d\u306b\u4f7f\u7528\u3002<\/li>\n\n\n\n<li><code>empty()<\/code>: \u30d5\u30a9\u30fc\u30e0\u5165\u529b\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u53d6\u5f97\u7d50\u679c\u306a\u3069\u3001\u5024\u304c\u7a7a\u3067\u306a\u3044\u3053\u3068\u3092\u78ba\u8a8d\u3057\u305f\u3044\u5834\u5408\u306b\u4f7f\u7528\u3002\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u3067\u7279\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b9f\u969b\u306e\u4f7f\u7528\u4f8b\n$userData = [\n    'name' =&gt; 'Yamada',\n    'email' =&gt; '',\n    \/\/ age is not set\n];\n\n\/\/ isset()\u306e\u9069\u5207\u306a\u4f7f\u3044\u65b9 - \u30ad\u30fc\u306e\u5b58\u5728\u78ba\u8a8d\nif (isset($userData['name'])) {\n    echo \"\u540d\u524d\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u5b58\u5728\u3057\u307e\u3059\";\n}\n\n\/\/ empty()\u306e\u9069\u5207\u306a\u4f7f\u3044\u65b9 - \u5024\u304c\u7a7a\u3067\u306a\u3044\u304b\u306e\u78ba\u8a8d\nif (!empty($userData['email'])) {\n    echo \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u3059\";\n} else {\n    echo \"\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u305b\u3093\"; \/\/ \u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n\n\/\/ \u7d44\u307f\u5408\u308f\u305b\u305f\u4f7f\u3044\u65b9\nif (isset($userData['age']) &amp;&amp; !empty($userData['age'])) {\n    echo \"\u5e74\u9f62\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u3059\";\n} else {\n    echo \"\u5e74\u9f62\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u306a\u3044\u304b\u3001\u5b58\u5728\u3057\u307e\u305b\u3093\"; \/\/ \u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-6\">empty()\u3068is_null()\u3092\u6df7\u540c\u3057\u306a\u3044\u305f\u3081\u306e\u77e5\u8b58<\/h3>\n\n\n\n<p><code>empty()<\/code>\u3068<code>is_null()<\/code>\u3082\u6df7\u540c\u3055\u308c\u304c\u3061\u3067\u3059\u304c\u3001\u305d\u306e\u76ee\u7684\u306f\u5927\u304d\u304f\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p><strong>is_null()\u306e\u7279\u5fb4:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5909\u6570\u304c<code>null<\/code>\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u306e\u307f\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b<\/li>\n\n\n\n<li>\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066\u306f\u30a8\u30e9\u30fc\u3092\u767a\u751f\u3055\u305b\u308b<\/li>\n\n\n\n<li>\u95a2\u6570\u3067\u3042\u308a\u3001\u8a00\u8a9e\u69cb\u9020\u3067\u306f\u306a\u3044\uff08\u82e5\u5e72\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u3042\u308b\uff09<\/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=\"\">$a = null;\n$b = '';\n$c = 0;\n\/\/ $d \u306f\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u306a\u3044\n\n\/\/ is_null()\u306e\u7d50\u679c\nvar_dump(is_null($a));  \/\/ bool(true) - null\u306a\u306e\u3067true\nvar_dump(is_null($b));  \/\/ bool(false) - \u7a7a\u6587\u5b57\u5217\u306fnull\u3067\u306f\u306a\u3044\nvar_dump(is_null($c));  \/\/ bool(false) - 0\u306fnull\u3067\u306f\u306a\u3044\n\/\/ var_dump(is_null($d)); \/\/ \u30a8\u30e9\u30fc: Undefined variable\n\n\/\/ empty()\u306e\u7d50\u679c\uff08\u6bd4\u8f03\u306e\u305f\u3081\uff09\nvar_dump(empty($a));  \/\/ bool(true) - null\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($b));  \/\/ bool(true) - \u7a7a\u6587\u5b57\u5217\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($c));  \/\/ bool(true) - 0\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\nvar_dump(empty($d));  \/\/ bool(true) - \u672a\u5b9a\u7fa9\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\n<\/pre>\n\n\n\n<p><strong>\u4f7f\u7528\u30b7\u30fc\u30f3:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>is_null()<\/code>: \u660e\u793a\u7684\u306b<code>null<\/code>\u5024\u304b\u3069\u3046\u304b\u3092\u691c\u8a3c\u3057\u305f\u3044\u5834\u5408\u306b\u4f7f\u7528\u3002\u30aa\u30d7\u30b7\u30e7\u30ca\u30eb\u306a\u30d1\u30e9\u30e1\u30fc\u30bf\u304c<code>null<\/code>\u304b\u3069\u3046\u304b\u306e\u5224\u5b9a\u306a\u3069\u3002<\/li>\n\n\n\n<li><code>empty()<\/code>: \u5024\u304c\u5b9f\u8cea\u7684\u306b\u7a7a\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044\u5834\u5408\u306b\u4f7f\u7528\u3002\u5165\u529b\u30d5\u30a3\u30fc\u30eb\u30c9\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u53d6\u5f97\u7d50\u679c\u306a\u3069\u3001\u8907\u6570\u306e\u300c\u7a7a\u300d\u306e\u72b6\u614b\u3092\u4e00\u5ea6\u306b\u30c1\u30a7\u30c3\u30af\u3067\u304d\u308b\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-7\">empty()\u3068!\u6f14\u7b97\u306e\u6bd4\u8f03 \u2013 \u3069\u3061\u3089\u304c\u6b63\u3057\u3044\u304b<\/h3>\n\n\n\n<p><code>empty()<\/code>\u3068\u8ad6\u7406\u5426\u5b9a\u6f14\u7b97\u5b50(<code>!<\/code>)\u3092\u4f7f\u3063\u305f\u5224\u5b9a\u3082\u3001\u4e00\u898b\u4f3c\u3066\u3044\u308b\u3088\u3046\u3067\u3001\u7d50\u679c\u304c\u7570\u306a\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p><strong>!\u6f14\u7b97\u5b50\u306e\u7279\u5fb4:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5024\u3092\u30d6\u30fc\u30eb\u578b\u306b\u5909\u63db\u3057\u3066\u304b\u3089\u5426\u5b9a\u3059\u308b<\/li>\n\n\n\n<li>PHP\u306e\u578b\u5909\u63db\u898f\u5247\u306b\u5f93\u3046\uff080\u3001\u7a7a\u6587\u5b57\u5217\u3001null\u3001false\u306a\u3069\u306f<code>false<\/code>\u306b\u5909\u63db\u3055\u308c\u308b\uff09<\/li>\n\n\n\n<li><code>empty()<\/code>\u3068\u4f3c\u305f\u7d50\u679c\u306b\u306a\u308b\u304c\u3001\u3059\u3079\u3066\u306e\u5834\u5408\u3067\u540c\u3058\u3067\u306f\u306a\u3044<\/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=\"\">$a = 0;\n$b = '0';\n$c = [];\n$d = '   ';\n\n\/\/ !\u6f14\u7b97\u5b50\u306e\u7d50\u679c\nvar_dump(!$a);       \/\/ bool(true) - 0\u306ffalse\u306b\u5909\u63db\u3055\u308c\u3001\u305d\u308c\u3092\u5426\u5b9a\nvar_dump(!$b);       \/\/ bool(true) - '0'\u306ffalse\u306b\u5909\u63db\u3055\u308c\u3001\u305d\u308c\u3092\u5426\u5b9a\nvar_dump(!$c);       \/\/ bool(true) - \u7a7a\u914d\u5217\u306ffalse\u306b\u5909\u63db\u3055\u308c\u3001\u305d\u308c\u3092\u5426\u5b9a\nvar_dump(!$d);       \/\/ bool(false) - \u7a7a\u767d\u6587\u5b57\u5217\u306f\u7a7a\u3067\u306f\u306a\u3044\u3068\u307f\u306a\u3055\u308c\u308b\n\n\/\/ empty()\u306e\u7d50\u679c\uff08\u6bd4\u8f03\u306e\u305f\u3081\uff09\nvar_dump(empty($a));  \/\/ bool(true)\nvar_dump(empty($b));  \/\/ bool(true)\nvar_dump(empty($c));  \/\/ bool(true)\nvar_dump(empty($d));  \/\/ bool(false) - \u7a7a\u767d\u306e\u307f\u306e\u6587\u5b57\u5217\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044\n<\/pre>\n\n\n\n<p><strong>\u3069\u3061\u3089\u304c\u6b63\u3057\u3044\u304b:<\/strong> \u6b63\u3057\u3044\u3082\u9593\u9055\u3044\u3082\u3042\u308a\u307e\u305b\u3093\u304c\u3001\u4f7f\u3044\u5206\u3051\u306e\u30dd\u30a4\u30f3\u30c8\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>empty()<\/code>: \u660e\u793a\u7684\u306b\u300c\u7a7a\u300d\u306e\u5024\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044\u5834\u5408\u3084\u3001\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u3082\u5b89\u5168\u306b\u6271\u3044\u305f\u3044\u5834\u5408\u306b\u4f7f\u7528<\/li>\n\n\n\n<li><code>!\u6f14\u7b97\u5b50<\/code>: \u5024\u3092\u30d6\u30fc\u30eb\u578b\u3068\u3057\u3066\u8a55\u4fa1\u3057\u3001\u305d\u306e\u8ad6\u7406\u53cd\u8ee2\u304c\u5fc5\u8981\u306a\u5834\u5408\u306b\u4f7f\u7528<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b9f\u969b\u306e\u4f7f\u3044\u5206\u3051\u4f8b\n$userInput = '   ';  \/\/ \u30b9\u30da\u30fc\u30b9\u306e\u307f\u306e\u5165\u529b\n\n\/\/ empty()\u306e\u5834\u5408\nif (empty($userInput)) {\n    echo \"\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u3059: '\" . $userInput . \"'\"; \/\/ \u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n\n\/\/ !\u6f14\u7b97\u5b50\u306e\u5834\u5408\nif (!$userInput) {\n    echo \"\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u305b\u3093\";\n} else {\n    echo \"\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u3059: '\" . $userInput . \"'\"; \/\/ \u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n\n\/\/ \u7a7a\u767d\u3092\u30c8\u30ea\u30e0\u3057\u305f\u5834\u5408\nif (empty(trim($userInput))) {\n    echo \"\u5b9f\u8cea\u7684\u306b\u5165\u529b\u3055\u308c\u3066\u3044\u307e\u305b\u3093\"; \/\/ \u3053\u3061\u3089\u304c\u5b9f\u884c\u3055\u308c\u308b\n}\n<\/pre>\n\n\n\n<p>\u9069\u5207\u306a\u95a2\u6570\u3092\u9078\u629e\u3059\u308b\u305f\u3081\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5909\u6570\u304c\u5b58\u5728\u3059\u308b\u304b\u3069\u3046\u304b\u306e\u307f\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044 \u2192 <code>isset()<\/code><\/li>\n\n\n\n<li>\u5909\u6570\u304cnull\u304b\u3069\u3046\u304b\u306e\u307f\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044 \u2192 <code>is_null()<\/code><\/li>\n\n\n\n<li>\u5909\u6570\u304c\u300c\u7a7a\u300d\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u3044\uff08\u672a\u5b9a\u7fa9\u3001null\u3001\u7a7a\u6587\u5b57\u5217\u30010\u306a\u3069\uff09 \u2192 <code>empty()<\/code><\/li>\n\n\n\n<li>\u5024\u3092\u30d6\u30fc\u30eb\u578b\u3068\u3057\u3066\u8a55\u4fa1\u3057\u3001\u305d\u306e\u9006\u3092\u5f97\u305f\u3044 \u2192 <code>!\u6f14\u7b97\u5b50<\/code><\/li>\n<\/ol>\n\n\n\n<p>\u72b6\u6cc1\u306b\u5fdc\u3058\u3066\u9069\u5207\u306a\u95a2\u6570\u3092\u9078\u3073\u3001\u30b3\u30fc\u30c9\u306e\u610f\u56f3\u3092\u660e\u78ba\u306b\u4f1d\u3048\u308b\u3053\u3068\u304c\u3001\u30d0\u30b0\u306e\u5c11\u306a\u3044\u54c1\u8cea\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u30b3\u30c4\u3067\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-8\">\u5b9f\u8df5\u4f8b1: \u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3<\/h2>\n\n\n\n<p>Web\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u306b\u304a\u3044\u3066\u3001\u30e6\u30fc\u30b6\u30fc\u304b\u3089\u306e\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u3092\u9069\u5207\u306b\u691c\u8a3c\u3059\u308b\u3053\u3068\u306f\u975e\u5e38\u306b\u91cd\u8981\u3067\u3059\u3002<code>empty()<\/code>\u95a2\u6570\u306f\u3053\u306e\u30d5\u30a9\u30fc\u30e0\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u306e\u6700\u524d\u7dda\u3067\u6d3b\u8e8d\u3057\u307e\u3059\u3002\u5fc5\u9808\u9805\u76ee\u304c\u5165\u529b\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b\u5358\u7d14\u306a\u7528\u9014\u304b\u3089\u3001\u8907\u96d1\u306a\u30d5\u30a9\u30fc\u30e0\u8981\u7d20\u306e\u691c\u8a3c\u307e\u3067\u3001\u5e45\u5e83\u304f\u6d3b\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-9\">\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u691c\u8a3c\u3067empty()\u3092\u52b9\u679c\u7684\u306b\u4f7f\u3046\u65b9\u6cd5<\/h3>\n\n\n\n<p><code>empty()<\/code>\u95a2\u6570\u306f\u3001\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u691c\u8a3c\u306b\u304a\u3044\u3066\u3068\u3066\u3082\u4fbf\u5229\u3067\u3059\u304c\u3001\u52b9\u679c\u7684\u306b\u4f7f\u3046\u305f\u3081\u306b\u306f\u3044\u304f\u3064\u304b\u306e\u30c6\u30af\u30cb\u30c3\u30af\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=\"\">\/\/ \u57fa\u672c\u7684\u306a\u30d5\u30a9\u30fc\u30e0\u691c\u8a3c\u306e\u4f8b\nif ($_SERVER['REQUEST_METHOD'] === 'POST') {\n    $errors = [];\n    \n    \/\/ \u5fc5\u9808\u9805\u76ee\u306e\u30c1\u30a7\u30c3\u30af\n    if (empty($_POST['username'])) {\n        $errors[] = '\u30e6\u30fc\u30b6\u30fc\u540d\u306f\u5fc5\u9808\u3067\u3059';\n    }\n    \n    \/\/ \u7a7a\u767d\u3060\u3051\u306e\u5165\u529b\u3092\u9632\u3050\uff08trim()\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\uff09\n    if (empty(trim($_POST['message']))) {\n        $errors[] = '\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n    }\n    \n    \/\/ \u6570\u5024\u306e0\u3092\u6709\u52b9\u306a\u5165\u529b\u3068\u3057\u3066\u6271\u3046\u5834\u5408\n    if (!isset($_POST['age']) || $_POST['age'] === '') {\n        $errors[] = '\u5e74\u9f62\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n    }\n    \n    \/\/ \u30a8\u30e9\u30fc\u304c\u306a\u3051\u308c\u3070\u51e6\u7406\u3092\u7d9a\u884c\n    if (empty($errors)) {\n        \/\/ \u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u306e\u7d9a\u884c...\n    }\n}\n<\/pre>\n\n\n\n<p>\u7279\u306b\u6ce8\u610f\u3059\u3079\u304d\u30dd\u30a4\u30f3\u30c8\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u7a7a\u767d\u6587\u5b57\u306e\u51e6\u7406<\/strong>: \u30e6\u30fc\u30b6\u30fc\u304c\u30b9\u30da\u30fc\u30b9\u3060\u3051\u3092\u5165\u529b\u3057\u305f\u5834\u5408\u3082\u691c\u51fa\u3059\u308b\u305f\u3081\u306b\u3001<code>trim()<\/code>\u3068\u7d44\u307f\u5408\u308f\u305b\u308b<\/li>\n\n\n\n<li><strong>\u6570\u5024\u306e0\u306e\u6271\u3044<\/strong>: \u5e74\u9f62\u3084\u6570\u91cf\u306a\u3069\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u30670\u304c\u6709\u52b9\u306a\u5024\u3067\u3042\u308b\u5834\u5408\u306f\u3001<code>empty()<\/code>\u3067\u306f\u306a\u304f\u5225\u306e\u691c\u8a3c\u65b9\u6cd5\u3092\u4f7f\u7528\u3059\u308b<\/li>\n\n\n\n<li><strong>\u8907\u6570\u9078\u629e\u30d5\u30a9\u30fc\u30e0\u8981\u7d20\u306e\u691c\u8a3c<\/strong>: \u30c1\u30a7\u30c3\u30af\u30dc\u30c3\u30af\u30b9\u306a\u3069\u306e\u8907\u6570\u9078\u629e\u53ef\u80fd\u306a\u8981\u7d20\u306f\u914d\u5217\u3068\u3057\u3066\u9001\u4fe1\u3055\u308c\u308b\u305f\u3081\u3001\u9069\u5207\u306b\u51e6\u7406\u3059\u308b<\/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=\"\">\/\/ \u8907\u6570\u9078\u629e\u8981\u7d20\uff08\u30c1\u30a7\u30c3\u30af\u30dc\u30c3\u30af\u30b9\uff09\u306e\u691c\u8a3c\u4f8b\nif (empty($_POST['interests']) || !is_array($_POST['interests'])) {\n    $errors[] = '\u8208\u5473\u306e\u3042\u308b\u5206\u91ce\u3092\u5c11\u306a\u304f\u3068\u30821\u3064\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n\n\/\/ \u30bb\u30ec\u30af\u30c8\u30dc\u30c3\u30af\u30b9\u306e\u5fc5\u9808\u30c1\u30a7\u30c3\u30af\nif (empty($_POST['prefecture']) || $_POST['prefecture'] === '\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044') {\n    $errors[] = '\u90fd\u9053\u5e9c\u770c\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-10\">\u3088\u304f\u3042\u308b\u5b9f\u88c5\u30df\u30b9\u3068\u305d\u306e\u56de\u907f\u7b56<\/h3>\n\n\n\n<p>\u30d5\u30a9\u30fc\u30e0\u691c\u8a3c\u306b\u304a\u3051\u308b<code>empty()<\/code>\u306e\u4f7f\u7528\u306b\u306f\u3001\u3088\u304f\u3042\u308b\u843d\u3068\u3057\u7a74\u304c\u3044\u304f\u3064\u304b\u5b58\u5728\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p><strong>1. \u201c0\u201d\u3068\u3044\u3046\u6587\u5b57\u5217\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u554f\u984c<\/strong><\/p>\n\n\n\n<p><code>empty()<\/code>\u306f\u6587\u5b57\u5217\u306e\u201d0\u2033\u3082\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3059\u308b\u305f\u3081\u3001\u6570\u5024\u5165\u529b\u30d5\u30a3\u30fc\u30eb\u30c9\u3067\u554f\u984c\u306b\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (empty($_POST['quantity'])) {\n    $errors[] = '\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n\n\/\/ \u6539\u5584\u3055\u308c\u305f\u30b3\u30fc\u30c9\nif (!isset($_POST['quantity']) || $_POST['quantity'] === '') {\n    $errors[] = '\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n} elseif (!is_numeric($_POST['quantity'])) {\n    $errors[] = '\u6570\u91cf\u306f\u6570\u5024\u3067\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n<\/pre>\n\n\n\n<p><strong>2. \u672a\u9078\u629e\u306e\u30c1\u30a7\u30c3\u30af\u30dc\u30c3\u30af\u30b9\u3084\u30e9\u30b8\u30aa\u30dc\u30bf\u30f3\u306e\u6271\u3044<\/strong><\/p>\n\n\n\n<p>\u30c1\u30a7\u30c3\u30af\u30dc\u30c3\u30af\u30b9\u306f\u9078\u629e\u3055\u308c\u306a\u3044\u5834\u5408\u3001POST\u30c7\u30fc\u30bf\u306b\u542b\u307e\u308c\u306a\u3044\u3068\u3044\u3046HTML\u306e\u4ed5\u69d8\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (empty($_POST['terms'])) {\n    $errors[] = '\u5229\u7528\u898f\u7d04\u306b\u540c\u610f\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n\n\/\/ \u6539\u5584\u3055\u308c\u305f\u30b3\u30fc\u30c9 - isset()\u3092\u4f7f\u7528\nif (!isset($_POST['terms'])) {\n    $errors[] = '\u5229\u7528\u898f\u7d04\u306b\u540c\u610f\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n\n\/\/ \u307e\u305f\u306f hidden \u30d5\u30a3\u30fc\u30eb\u30c9\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u65b9\u6cd5\n\/\/ HTML\u5074: &lt;input type=\"hidden\" name=\"terms_submitted\" value=\"1\"&gt;\nif (!empty($_POST['terms_submitted']) &amp;&amp; empty($_POST['terms'])) {\n    $errors[] = '\u5229\u7528\u898f\u7d04\u306b\u540c\u610f\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n<\/pre>\n\n\n\n<p><strong>3. \u914d\u5217\u5f62\u5f0f\u306e\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u691c\u8a3c\u30df\u30b9<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (empty($_POST['options'])) {\n    $errors[] = '\u30aa\u30d7\u30b7\u30e7\u30f3\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n\n\/\/ \u6539\u5584\u3055\u308c\u305f\u30b3\u30fc\u30c9 - \u7a7a\u306e\u914d\u5217\u3082\u691c\u51fa\nif (empty($_POST['options']) || (is_array($_POST['options']) &amp;&amp; count($_POST['options']) === 0)) {\n    $errors[] = '\u30aa\u30d7\u30b7\u30e7\u30f3\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n<\/pre>\n\n\n\n<p><strong>4. \u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u9762\u3067\u306e\u6ce8\u610f\u70b9<\/strong><\/p>\n\n\n\n<p><code>empty()<\/code>\u306f\u3042\u304f\u307e\u3067\u5024\u304c\u300c\u7a7a\u300d\u304b\u3069\u3046\u304b\u3092\u691c\u8a3c\u3059\u308b\u3060\u3051\u3067\u3042\u308a\u3001\u5165\u529b\u5024\u306e\u5b89\u5168\u6027\u3092\u78ba\u4fdd\u3059\u308b\u305f\u3081\u306b\u306f\u4e0d\u5341\u5206\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u3088\u308a\u5b8c\u5168\u306a\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u4f8b\nif (!empty($_POST['email'])) {\n    \/\/ \u5024\u306f\u5b58\u5728\u3059\u308b\u304c\u3001\u6709\u52b9\u306a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u304b\uff1f\n    if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {\n        $errors[] = '\u6709\u52b9\u306a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n    }\n} else {\n    $errors[] = '\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306f\u5fc5\u9808\u3067\u3059';\n}\n\n\/\/ SQL\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u5bfe\u7b56\n$username = !empty($_POST['username']) ? htmlspecialchars($_POST['username']) : '';\n$query = \"SELECT * FROM users WHERE username = ?\";\n$stmt = $pdo-&gt;prepare($query);\n$stmt-&gt;execute([$username]);\n<\/pre>\n\n\n\n<p>\u30d5\u30a9\u30fc\u30e0\u691c\u8a3c\u3067\u306f\u3001<code>empty()<\/code>\u306f\u975e\u5e38\u306b\u4fbf\u5229\u306a\u30c4\u30fc\u30eb\u3067\u3059\u304c\u3001\u305d\u308c\u3060\u3051\u306b\u983c\u3089\u305a\u3001\u9069\u5207\u306a\u578b\u30c1\u30a7\u30c3\u30af\u3084\u30b5\u30cb\u30bf\u30a4\u30ba\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u3046\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u307e\u305f\u3001\u30af\u30e9\u30a4\u30a2\u30f3\u30c8\u30b5\u30a4\u30c9\u3068\u30b5\u30fc\u30d0\u30fc\u30b5\u30a4\u30c9\u306e\u4e21\u65b9\u3067\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u3092\u884c\u3046\u3053\u3068\u3067\u3001\u30e6\u30fc\u30b6\u30d3\u30ea\u30c6\u30a3\u3068\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u306e\u4e21\u65b9\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-11\">\u5b9f\u8df5\u4f8b2: \u914d\u5217\u3068\u9023\u60f3\u914d\u5217\u3067\u306e\u6d3b\u7528\u6cd5<\/h2>\n\n\n\n<p>PHP\u306e\u914d\u5217\u64cd\u4f5c\u306b\u304a\u3044\u3066\u3001<code>empty()<\/code>\u95a2\u6570\u306f\u975e\u5e38\u306b\u4fbf\u5229\u306a\u30c4\u30fc\u30eb\u3067\u3059\u3002\u30c7\u30fc\u30bf\u51e6\u7406\u3084API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\u3001\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u306e\u64cd\u4f5c\u306a\u3069\u3001\u591a\u304f\u306e\u5834\u9762\u3067\u6d3b\u8e8d\u3057\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u914d\u5217\u3068\u9023\u60f3\u914d\u5217\u306b\u304a\u3051\u308b<code>empty()<\/code>\u306e\u52b9\u679c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u914d\u5217\u8981\u7d20\u306e\u5b58\u5728\u78ba\u8a8d\u3068empty()\u306e\u95a2\u4fc2<\/h3>\n\n\n\n<p>\u914d\u5217\u3092\u6271\u3046\u969b\u3001\u8981\u7d20\u306e\u5b58\u5728\u78ba\u8a8d\u3068\u5024\u306e\u691c\u8a3c\u306f\u57fa\u672c\u7684\u306a\u64cd\u4f5c\u3067\u3059\u3002<code>empty()<\/code>\u306f\u3001\u3053\u308c\u3089\u306e\u64cd\u4f5c\u3092\u52b9\u7387\u7684\u306b\u884c\u3046\u305f\u3081\u306b\u4f7f\u7528\u3067\u304d\u307e\u3059\u304c\u3001\u3044\u304f\u3064\u304b\u6ce8\u610f\u70b9\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=\"\">\/\/ \u57fa\u672c\u7684\u306a\u914d\u5217\u64cd\u4f5c\u3067\u306eempty()\u306e\u4f7f\u7528\u4f8b\n$fruits = ['apple', 'banana', 'orange'];\n$emptyArray = [];\n\nvar_dump(empty($fruits));      \/\/ bool(false) - \u8981\u7d20\u304c\u3042\u308b\u306e\u3067\u7a7a\u3067\u306f\u306a\u3044\nvar_dump(empty($emptyArray));  \/\/ bool(true) - \u7a7a\u306e\u914d\u5217\n\n\/\/ \u914d\u5217\u8981\u7d20\u306e\u30c1\u30a7\u30c3\u30af\nvar_dump(empty($fruits[0]));   \/\/ bool(false) - 'apple'\u306f\u7a7a\u3067\u306f\u306a\u3044\nvar_dump(empty($fruits[3]));   \/\/ bool(true) - \u5b58\u5728\u3057\u306a\u3044\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\n\n\/\/ \u9023\u60f3\u914d\u5217\n$user = [\n    'name' =&gt; 'Tanaka',\n    'email' =&gt; '',\n    'phone' =&gt; null\n];\n\nvar_dump(empty($user['name']));   \/\/ bool(false) - \u5024\u304c\u5b58\u5728\u3059\u308b\nvar_dump(empty($user['email']));  \/\/ bool(true) - \u7a7a\u6587\u5b57\u5217\nvar_dump(empty($user['phone']));  \/\/ bool(true) - null\u5024\nvar_dump(empty($user['address'])); \/\/ bool(true) - \u5b58\u5728\u3057\u306a\u3044\u30ad\u30fc\n<\/pre>\n\n\n\n<p><strong>\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8\uff1a<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>empty($array)<\/code>\u306f\u914d\u5217\u81ea\u4f53\u304c\u7a7a\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3057\u307e\u3059<\/li>\n\n\n\n<li><code>empty($array[key])<\/code>\u306f\u7279\u5b9a\u306e\u8981\u7d20\u306e\u5024\u304c\u300c\u7a7a\u300d\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3057\u307e\u3059<\/li>\n\n\n\n<li>\u5b58\u5728\u3057\u306a\u3044\u30ad\u30fc\u3084\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306b\u5bfe\u3057\u3066\u3082<code>empty()<\/code>\u306f\u5b89\u5168\u306b\u4f7f\u7528\u3067\u304d\u3001<code>true<\/code>\u3092\u8fd4\u3057\u307e\u3059<\/li>\n<\/ol>\n\n\n\n<p>\u5b9f\u969b\u306e\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u3067\u306f\u3001<code>isset()<\/code>\u3068<code>empty()<\/code>\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b\u30d1\u30bf\u30fc\u30f3\u304c\u4e00\u822c\u7684\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ isset()\u3068empty()\u306e\u7d44\u307f\u5408\u308f\u305b\n$data = getDataFromAPI(); \/\/ \u4f55\u3089\u304b\u306eAPI\u304b\u3089\u30c7\u30fc\u30bf\u3092\u53d6\u5f97\n\n\/\/ \u63a8\u5968\u30d1\u30bf\u30fc\u30f31: \u30ad\u30fc\u306e\u5b58\u5728\u78ba\u8a8d\u3068\u5024\u306e\u691c\u8a3c\u3092\u5206\u3051\u308b\nif (isset($data['items']) &amp;&amp; !empty($data['items'])) {\n    \/\/ items \u30ad\u30fc\u304c\u5b58\u5728\u3057\u3001\u7a7a\u3067\u306a\u3044\u914d\u5217\u304c\u5165\u3063\u3066\u3044\u308b\n    foreach ($data['items'] as $item) {\n        \/\/ \u51e6\u7406...\n    }\n}\n\n\/\/ \u63a8\u5968\u30d1\u30bf\u30fc\u30f32: \u76f4\u63a5\u30a2\u30af\u30bb\u30b9\u3057\u3066\u7c21\u6f54\u306b\u66f8\u304f\uff08PHP\u306e Notice \u30a8\u30e9\u30fc\u3092\u6291\u5236\u3059\u308b\u8a2d\u5b9a\u304c\u3042\u308b\u5834\u5408\uff09\nif (!empty($data['items'])) {\n    \/\/ items \u30ad\u30fc\u304c\u5b58\u5728\u3057\u3001\u7a7a\u3067\u306a\u3044\u5024\u304c\u5165\u3063\u3066\u3044\u308b\n    \/\/ \u6ce8: data['items']\u304c\u672a\u5b9a\u7fa9\u3067\u3082\u30a8\u30e9\u30fc\u306b\u306a\u3089\u305a\u3001\u5358\u306btrue\u304c\u8fd4\u308b\n}\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-13\">\u591a\u6b21\u5143\u914d\u5217\u3067\u6ce8\u610f\u3059\u3079\u304d\u52d5\u4f5c<\/h3>\n\n\n\n<p>\u591a\u6b21\u5143\u914d\u5217\uff08\u914d\u5217\u306e\u4e2d\u306b\u914d\u5217\u304c\u542b\u307e\u308c\u308b\u69cb\u9020\uff09\u3092\u6271\u3046\u969b\u306b\u306f\u3001<code>empty()<\/code>\u306e\u4f7f\u7528\u306b\u7279\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002\u968e\u5c64\u304c\u6df1\u304f\u306a\u308b\u307b\u3069\u3001\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3059\u308b\u30ea\u30b9\u30af\u304c\u9ad8\u307e\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=\"\">\/\/ \u591a\u6b21\u5143\u914d\u5217\u306e\u4f8b\n$userData = [\n    'profile' =&gt; [\n        'name' =&gt; 'Suzuki',\n        'contacts' =&gt; [\n            'email' =&gt; 'suzuki@example.com',\n            'social' =&gt; []\n        ]\n    ],\n    'settings' =&gt; null\n];\n\n\/\/ \u554f\u984c\u306e\u3042\u308b\u30a2\u30af\u30bb\u30b9\u65b9\u6cd5\nif (!empty($userData['profile']['contacts']['phone'])) {\n    \/\/ phone \u30ad\u30fc\u306f\u5b58\u5728\u3057\u306a\u3044\u304c\u3001\u30a8\u30e9\u30fc\u306f\u767a\u751f\u3057\u306a\u3044\n}\n\n\/\/ \u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\u65b9\u6cd5 - \u968e\u5c64\u3054\u3068\u306e\u78ba\u8a8d\nif (\n    !empty($userData['profile']) &amp;&amp; \n    !empty($userData['profile']['contacts']) &amp;&amp; \n    !empty($userData['profile']['contacts']['phone'])\n) {\n    \/\/ \u3059\u3079\u3066\u306e\u968e\u5c64\u304c\u5b58\u5728\u3057\u3001\u5024\u3082\u7a7a\u3067\u306a\u3044\u5834\u5408\n}\n\n\/\/ \u3088\u308a\u7c21\u6f54\u306a\u66f8\u304d\u65b9\uff08PHP 7.0\u4ee5\u964d\uff09\nif (!empty($userData['profile']['contacts']['phone'] ?? null)) {\n    \/\/ Null\u5408\u4f53\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\u3057\u305f\u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\n}\n<\/pre>\n\n\n\n<p>\u591a\u6b21\u5143\u914d\u5217\u3067\u306e\u6ce8\u610f\u70b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u89aa\u306e\u968e\u5c64\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u3001\u5b50\u306e\u968e\u5c64\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3067\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059<\/li>\n\n\n\n<li><code>empty()<\/code>\u306f\u6700\u521d\u306e\u968e\u5c64\u306e\u5b58\u5728\u78ba\u8a8d\u306b\u306f\u4f7f\u3048\u307e\u3059\u304c\u3001\u6df1\u3044\u968e\u5c64\u306e\u30a2\u30af\u30bb\u30b9\u306b\u306f\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059<\/li>\n\n\n\n<li>PHP 7.0\u4ee5\u964d\u3067\u306f\u3001Null\u5408\u4f53\u6f14\u7b97\u5b50\uff08<code>??<\/code>\uff09\u3092\u4f7f\u3063\u3066\u5b89\u5168\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u3059<\/li>\n<\/ol>\n\n\n\n<p>\u5b9f\u969b\u306e\u30b3\u30fc\u30c9\u4f8b\uff1aAPI\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406<\/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=\"\">\/\/ API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\u4f8b\nfunction processAPIResponse($response) {\n    $result = [];\n    \n    \/\/ \u30c7\u30fc\u30bf\u306e\u5b58\u5728\u78ba\u8a8d\u3068\u51e6\u7406\n    if (!empty($response['data'])) {\n        $result['hasData'] = true;\n        \n        \/\/ \u8907\u6570\u306e\u7d50\u679c\u304c\u3042\u308b\u5834\u5408\u306e\u51e6\u7406\n        if (!empty($response['data']['results']) &amp;&amp; is_array($response['data']['results'])) {\n            foreach ($response['data']['results'] as $item) {\n                \/\/ \u5fc5\u8981\u306a\u9805\u76ee\u306e\u78ba\u8a8d\n                $name = !empty($item['name']) ? $item['name'] : '\u540d\u79f0\u306a\u3057';\n                $value = $item['value'] ?? 0; \/\/ \u6570\u5024\u306e\u5834\u5408\u30010\u306f\u6709\u52b9\u306a\u5024\u304b\u3082\u3057\u308c\u306a\u3044\n                \n                $result['items'][] = [\n                    'name' =&gt; $name,\n                    'value' =&gt; $value\n                ];\n            }\n        }\n    } else {\n        $result['hasData'] = false;\n    }\n    \n    return $result;\n}\n<\/pre>\n\n\n\n<p>\u914d\u5217\u51e6\u7406\u306b\u304a\u3051\u308b<code>empty()<\/code>\u306e\u6d3b\u7528\u306f\u3001\u7279\u306b\u30c7\u30fc\u30bf\u306e\u691c\u8a3c\u3084\u6761\u4ef6\u5206\u5c90\u306e\u7c21\u7565\u5316\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u914d\u5217\u306e\u69cb\u9020\u304c\u8907\u96d1\u306b\u306a\u308b\u307b\u3069\u3001\u968e\u5c64\u3054\u3068\u306e\u78ba\u8a8d\u3084\u5b89\u5168\u306a\u30a2\u30af\u30bb\u30b9\u65b9\u6cd5\u3092\u610f\u8b58\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u7279\u306b\u5916\u90e8API\u304b\u3089\u306e\u30c7\u30fc\u30bf\u3084\u3001\u5f62\u5f0f\u304c\u53b3\u5bc6\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u306a\u3044\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3092\u6271\u3046\u5834\u5408\u306f\u3001\u614e\u91cd\u306b\u30b3\u30fc\u30c9\u3092\u8a2d\u8a08\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-14\">\u5b9f\u8df5\u4f8b3: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u64cd\u4f5c\u306b\u304a\u3051\u308bempty()\u306e\u6319\u52d5<\/h2>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u304c\u4e00\u822c\u7684\u306aPHP\u306e\u958b\u767a\u74b0\u5883\u3067\u306f\u3001<code>empty()<\/code>\u95a2\u6570\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u76f8\u4e92\u4f5c\u7528\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u7279\u306b\u3001\u30ab\u30d7\u30bb\u30eb\u5316\u3055\u308c\u305f\u30d7\u30ed\u30d1\u30c6\u30a3\u3084\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u5834\u5408\u3001<code>empty()<\/code>\u306e\u6319\u52d5\u306f\u5c11\u3057\u8907\u96d1\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-15\">\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9__isset\u3068__empty\u306e\u5b9f\u88c5\u65b9\u6cd5<\/h3>\n\n\n\n<p>PHP\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u306f\u3001<code>__isset()<\/code>\u3068<code>__get()<\/code>\u3068\u3044\u3046\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u3001<code>empty()<\/code>\u3084<code>isset()<\/code>\u306e\u52d5\u4f5c\u3092\u30ab\u30b9\u30bf\u30de\u30a4\u30ba\u3059\u308b\u3053\u3068\u304c\u3067\u304d\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=\"\">class User {\n    private $data = [\n        'name' =&gt; 'Yamada',\n        'email' =&gt; 'yamada@example.com',\n        'active' =&gt; true,\n        'score' =&gt; 0\n    ];\n    \n    \/\/ isset()\u3084empty()\u304c\u547c\u3073\u51fa\u3055\u308c\u305f\u6642\u306b\u5b9f\u884c\u3055\u308c\u308b\n    public function __isset($name) {\n        \/\/ \u30c7\u30fc\u30bf\u914d\u5217\u306b\u30ad\u30fc\u304c\u5b58\u5728\u3059\u308b\u304b\u30c1\u30a7\u30c3\u30af\n        return isset($this-&gt;data[$name]);\n    }\n    \n    \/\/ \u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u30a2\u30af\u30bb\u30b9\u3055\u308c\u305f\u6642\u306b\u5b9f\u884c\u3055\u308c\u308b\n    public function __get($name) {\n        if (isset($this-&gt;data[$name])) {\n            return $this-&gt;data[$name];\n        }\n        return null;\n    }\n}\n\n$user = new User();\nvar_dump(isset($user-&gt;name));    \/\/ bool(true) - __isset()\u304c\u547c\u3070\u308c\u308b\nvar_dump(empty($user-&gt;name));    \/\/ bool(false) - __isset()\u304c\u547c\u3070\u308c\u3001\u5024\u306fempty()\u3067\u8a55\u4fa1\u3055\u308c\u308b\nvar_dump(empty($user-&gt;score));   \/\/ bool(true) - \u5024\u304c0\u306a\u306e\u3067empty()\u306ftrue\u3092\u8fd4\u3059\nvar_dump(empty($user-&gt;address)); \/\/ bool(true) - \u5b58\u5728\u3057\u306a\u3044\u30d7\u30ed\u30d1\u30c6\u30a3\n<\/pre>\n\n\n\n<p><strong>\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8\uff1a<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>empty()<\/code>\u306f\u5185\u90e8\u7684\u306b<code>isset()<\/code>\u3092\u30c1\u30a7\u30c3\u30af\u3057\u3066\u304b\u3089\u5024\u3092\u8a55\u4fa1\u3057\u307e\u3059<\/li>\n\n\n\n<li>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e<code>__isset()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001<code>isset()<\/code>\u3068<code>empty()<\/code>\u306e\u4e21\u65b9\u306b\u5f71\u97ff\u3057\u307e\u3059<\/li>\n\n\n\n<li><code>__empty()<\/code>\u3068\u3044\u3046\u30de\u30b8\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u306f\u5b58\u5728\u305b\u305a\u3001\u4ee3\u308f\u308a\u306b<code>__isset()<\/code>\u304c\u4f7f\u7528\u3055\u308c\u307e\u3059<\/li>\n<\/ol>\n\n\n\n<p>PHP 8.0\u4ee5\u964d\u3067\u306f\u3001<code>empty()<\/code>\u306e\u6319\u52d5\u306b\u91cd\u8981\u306a\u5909\u66f4\u304c\u3042\u308a\u307e\u3057\u305f\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ PHP 7.x\u4ee5\u524d\u306e\u52d5\u4f5c\nclass LegacyExample {\n    public function __isset($name) {\n        echo \"__isset called for $name\\n\";\n        return true; \/\/ \u5e38\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u306f\u5b58\u5728\u3059\u308b\u3068\u8fd4\u3059\n    }\n    \n    public function __get($name) {\n        echo \"__get called for $name\\n\";\n        return 0; \/\/ \u5e38\u306b0\u3092\u8fd4\u3059\n    }\n}\n\n$obj = new LegacyExample();\n\/\/ PHP 7.x\u4ee5\u524d: __isset called for prop \u2192 __get called for prop \u2192 true (0\u306fempty\u3068\u307f\u306a\u3055\u308c\u308b)\nvar_dump(empty($obj-&gt;prop));\n\n\/\/ PHP 8.0\u4ee5\u964d: __isset called for prop \u2192 __get called for prop \u2192 true (\u540c\u3058\u7d50\u679c)\n\/\/ \u3057\u304b\u3057\u5185\u90e8\u7684\u306a\u8a55\u4fa1\u9806\u5e8f\u304c\u660e\u78ba\u306b\u5b9a\u7fa9\u3055\u308c\u308b\u3088\u3046\u306b\u306a\u3063\u305f\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-16\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d7\u30ed\u30d1\u30c6\u30a3\u691c\u8a3c\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u3092\u691c\u8a3c\u3059\u308b\u969b\u306e\u63a8\u5968\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u3044\u304f\u3064\u304b\u7d39\u4ecb\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<p><strong>1. \u30ab\u30b9\u30bf\u30e0\u30b2\u30c3\u30bf\u30fc\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/strong><\/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    private $properties = [];\n    \n    public function __isset($name) {\n        return isset($this-&gt;properties[$name]);\n    }\n    \n    public function __get($name) {\n        return $this-&gt;properties[$name] ?? null;\n    }\n    \n    \/\/ \u30ab\u30b9\u30bf\u30e0\u30b2\u30c3\u30bf\u30fc\u306e\u4f8b\n    public function getPrice() {\n        \/\/ \u4fa1\u683c\u304c0\u3067\u3082\u6709\u52b9\u306a\u30b1\u30fc\u30b9\u304c\u3042\u308b\n        return $this-&gt;properties['price'] ?? null;\n    }\n    \n    \/\/ empty()\u306e\u4ee3\u308f\u308a\u306b\u30ab\u30b9\u30bf\u30e0\u691c\u8a3c\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\n    public function hasValidPrice() {\n        return isset($this-&gt;properties['price']) &amp;&amp; \n               is_numeric($this-&gt;properties['price']);\n    }\n}\n\n$product = new Product();\n\/\/ empty($product-&gt;price)\u306e\u4ee3\u308f\u308a\u306b\uff1a\nif ($product-&gt;hasValidPrice()) {\n    \/\/ \u51e6\u7406...\n}\n<\/pre>\n\n\n\n<p><strong>2. \u30b2\u30c3\u30bf\u30fc\u3068\u30bb\u30c3\u30bf\u30fc\u3092\u4f7f\u7528\u3057\u3001empty()\u306e\u4f7f\u7528\u3092\u6700\u5c0f\u9650\u306b<\/strong><\/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 UserProfile {\n    private $firstName = null;\n    private $lastName = null;\n    private $age = null;\n    \n    public function getFirstName() {\n        return $this-&gt;firstName;\n    }\n    \n    public function setFirstName($value) {\n        $this-&gt;firstName = $value;\n    }\n    \n    \/\/ \u540c\u69d8\u306b\u4ed6\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u3082...\n    \n    \/\/ \u30d5\u30eb\u30cd\u30fc\u30e0\u306e\u53d6\u5f97\u4f8b\n    public function getFullName() {\n        if (empty($this-&gt;firstName) &amp;&amp; empty($this-&gt;lastName)) {\n            return null;\n        }\n        \n        return trim($this-&gt;firstName . ' ' . $this-&gt;lastName);\n    }\n    \n    \/\/ \u8907\u5408\u7684\u306a\u691c\u8a3c\n    public function isProfileComplete() {\n        return !empty($this-&gt;firstName) &amp;&amp; \n               !empty($this-&gt;lastName) &amp;&amp; \n               !empty($this-&gt;age);\n    }\n}\n<\/pre>\n\n\n\n<p><strong>3. \u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30cf\u30a4\u30d6\u30ea\u30c3\u30c9<\/strong><\/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 DataCollection {\n    private $items = [];\n    \n    public function __isset($name) {\n        return isset($this-&gt;items[$name]);\n    }\n    \n    public function __get($name) {\n        return $this-&gt;items[$name] ?? null;\n    }\n    \n    \/\/ \u914d\u5217\u3068\u3057\u3066\u306e\u30a2\u30af\u30bb\u30b9\u3082\u53ef\u80fd\u306b\u3059\u308b\n    public function getItems() {\n        return $this-&gt;items;\n    }\n    \n    \/\/ \u7a7a\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\n    public function isEmpty() {\n        return empty($this-&gt;items);\n    }\n    \n    \/\/ \u7279\u5b9a\u306e\u30ad\u30fc\u304c\u7a7a\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\n    public function isValueEmpty($key) {\n        return empty($this-&gt;items[$key]);\n    }\n}\n<\/pre>\n\n\n\n<p>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u64cd\u4f5c\u306b\u304a\u3044\u3066<code>empty()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u969b\u306e\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><code>__isset()<\/code>\u3068<code>__get()<\/code>\u306e\u4e21\u65b9\u3092\u5b9f\u88c5\u3057\u3066\u6574\u5408\u6027\u3092\u4fdd\u3064<\/li>\n\n\n\n<li>\u5024\u304c\u300c0\u300d\u3084\u300c\u7a7a\u6587\u5b57\u5217\u300d\u3067\u3082\u6709\u52b9\u306a\u5834\u5408\u306f\u3001<code>empty()<\/code>\u306b\u983c\u3089\u305a\u30ab\u30b9\u30bf\u30e0\u30e1\u30bd\u30c3\u30c9\u3092\u691c\u8a0e\u3059\u308b<\/li>\n\n\n\n<li>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3084\u8907\u96d1\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u306f\u3001\u660e\u793a\u7684\u306a\u30a2\u30af\u30bb\u30b5\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\u3059\u308b<\/li>\n\n\n\n<li>PHP\u306e\u30d0\u30fc\u30b8\u30e7\u30f3\u306b\u3088\u308b\u52d5\u4f5c\u306e\u9055\u3044\u3092\u8003\u616e\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<p><code>empty()<\/code>\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u76f8\u4e92\u4f5c\u7528\u3092\u7406\u89e3\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\u7279\u306b\u3001\u8907\u96d1\u306a\u30d3\u30b8\u30cd\u30b9\u30ed\u30b8\u30c3\u30af\u3092\u6301\u3064\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u5358\u7d14\u306a<code>empty()<\/code>\u30c1\u30a7\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u30ab\u30b9\u30bf\u30e0\u30e1\u30bd\u30c3\u30c9\u3092\u901a\u3058\u3066\u610f\u56f3\u3092\u660e\u78ba\u306b\u8868\u73fe\u3059\u308b\u3053\u3068\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-17\">\u5b9f\u8df5\u4f8b4: \u6761\u4ef6\u5206\u5c90\u3067\u306e\u52b9\u7387\u7684\u306a\u4f7f\u3044\u65b9<\/h2>\n\n\n\n<p>\u6761\u4ef6\u5206\u5c90\u306f\u3001\u3042\u3089\u3086\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u306e\u57fa\u672c\u7684\u306a\u8981\u7d20\u3067\u3042\u308a\u3001PHP\u3067\u3082\u4f8b\u5916\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<code>empty()<\/code>\u95a2\u6570\u306f\u3001\u305d\u306e\u7c21\u6f54\u3055\u304b\u3089\u6761\u4ef6\u5206\u5c90\u3067\u983b\u7e41\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3092\u5411\u4e0a\u3055\u305b\u3001\u3088\u308a\u52b9\u7387\u7684\u306a\u30d7\u30ed\u30b0\u30e9\u30e0\u3092\u4f5c\u6210\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-18\">\u4e09\u9805\u6f14\u7b97\u5b50\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p><code>empty()<\/code>\u306f\u4e09\u9805\u6f14\u7b97\u5b50\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u975e\u5e38\u306b\u7c21\u6f54\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\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=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\n$username = empty($_POST['username']) ? '\u30b2\u30b9\u30c8' : $_POST['username'];\n\n\/\/ \u9023\u9396\u7684\u306a\u4f7f\u7528\u4f8b\n$message = empty($error) \n    ? (empty($success) ? '\u30c7\u30d5\u30a9\u30eb\u30c8\u30e1\u30c3\u30bb\u30fc\u30b8' : $success) \n    : $error;\n\n\/\/ HTML\u3067\u306e\u5fdc\u7528\u4f8b\necho '&lt;div class=\"' . (empty($errors) ? 'success' : 'error') . '\"&gt;';\necho empty($message) ? '\u60c5\u5831\u304c\u3042\u308a\u307e\u305b\u3093' : htmlspecialchars($message);\necho '&lt;\/div&gt;';\n<\/pre>\n\n\n\n<p>\u7279\u306b\u4fbf\u5229\u306a\u30d1\u30bf\u30fc\u30f3\u3068\u3057\u3066\u306f\u3001\u30d5\u30a9\u30fc\u30e0\u30c7\u30fc\u30bf\u306e\u51e6\u7406\u3084API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\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=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u30c7\u30fc\u30bf\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u8a2d\u5b9a\n$settings = [\n    'show_avatar' =&gt; empty($_POST['show_avatar']) ? false : true,\n    'theme' =&gt; empty($_POST['theme']) ? 'default' : $_POST['theme'],\n    'items_per_page' =&gt; empty($_POST['items_per_page']) ? 10 : (int)$_POST['items_per_page']\n];\n\n\/\/ API\u30ec\u30b9\u30dd\u30f3\u30b9\u306e\u51e6\u7406\n$userData = [\n    'name' =&gt; empty($response['user']['name']) ? '\u540d\u79f0\u672a\u8a2d\u5b9a' : $response['user']['name'],\n    'email' =&gt; empty($response['user']['email']) ? '' : $response['user']['email'],\n    'role' =&gt; empty($response['user']['role']) ? 'user' : $response['user']['role']\n];\n<\/pre>\n\n\n\n<p>\u6ce8\u610f\u70b9\u3068\u3057\u3066\u3001\u4e09\u9805\u6f14\u7b97\u5b50\u306e\u30cd\u30b9\u30c8\u304c\u6df1\u304f\u306a\u308b\u3068\u53ef\u8aad\u6027\u304c\u4f4e\u4e0b\u3059\u308b\u305f\u3081\u3001\u8907\u96d1\u306a\u30ed\u30b8\u30c3\u30af\u3067\u306f\u901a\u5e38\u306eif\u6587\u3092\u4f7f\u7528\u3057\u305f\u65b9\u304c\u826f\u3044\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-19\">\u8907\u6570\u306e\u6761\u4ef6\u3092\u898b\u6975\u3081\u308b\u969b\u306e\u8ad6\u7406\u7684\u306a\u8003\u3048\u65b9<\/h3>\n\n\n\n<p>\u8907\u6570\u306e\u6761\u4ef6\u3092\u52b9\u7387\u7684\u306b\u8a55\u4fa1\u3059\u308b\u305f\u3081\u306b\u306f\u3001\u8ad6\u7406\u6f14\u7b97\u5b50\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002PHP\u306f\u77ed\u7d61\u8a55\u4fa1\uff08short-circuit evaluation\uff09\u3092\u884c\u3046\u305f\u3081\u3001\u5de6\u5074\u306e\u6761\u4ef6\u304c\u7d50\u679c\u3092\u6c7a\u5b9a\u3067\u304d\u308b\u5834\u5408\u3001\u53f3\u5074\u306e\u8a55\u4fa1\u306f\u30b9\u30ad\u30c3\u30d7\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u52b9\u7387\u7684\u306a\u6761\u4ef6\u8a55\u4fa1\nif (empty($username) || empty($email)) {\n    echo \"\u30e6\u30fc\u30b6\u30fc\u540d\u3068\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306f\u5fc5\u9808\u3067\u3059\";\n    \/\/ username \u304c\u7a7a\u306a\u3089\u3001email \u306e\u30c1\u30a7\u30c3\u30af\u306f\u30b9\u30ad\u30c3\u30d7\u3055\u308c\u308b\n}\n\n\/\/ \u8907\u6570\u6761\u4ef6\u306e\u7d44\u307f\u5408\u308f\u305b\nif (!empty($user) &amp;&amp; !empty($user['permissions']) &amp;&amp; !empty($user['permissions']['admin'])) {\n    \/\/ \u30e6\u30fc\u30b6\u30fc\u304c\u7ba1\u7406\u8005\u6a29\u9650\u3092\u6301\u3063\u3066\u3044\u308b\u5834\u5408\u306e\u51e6\u7406\n}\n\n\/\/ \u3088\u308a\u8aad\u307f\u3084\u3059\u304f\u66f8\u304d\u63db\u3048\u305f\u4f8b\n$hasAdminPermission = !empty($user) \n    &amp;&amp; !empty($user['permissions']) \n    &amp;&amp; !empty($user['permissions']['admin']);\n\nif ($hasAdminPermission) {\n    \/\/ \u7ba1\u7406\u8005\u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>\u8907\u96d1\u306a\u6761\u4ef6\u306f\u95a2\u6570\u306b\u62bd\u51fa\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3068\u518d\u5229\u7528\u6027\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u6761\u4ef6\u30ed\u30b8\u30c3\u30af\u3092\u95a2\u6570\u306b\u62bd\u51fa\nfunction isValidUser($userData) {\n    return !empty($userData['id']) \n        &amp;&amp; !empty($userData['email']) \n        &amp;&amp; (!empty($userData['verified']) || !empty($userData['legacy_account']));\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nif (isValidUser($user)) {\n    \/\/ \u51e6\u7406...\n}\n<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30d2\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u6700\u3082\u5931\u6557\u3059\u308b\u53ef\u80fd\u6027\u304c\u9ad8\u3044\u3001\u307e\u305f\u306f\u8a08\u7b97\u30b3\u30b9\u30c8\u304c\u4f4e\u3044\u6761\u4ef6\u3092\u5148\u306b\u8a55\u4fa1\u3059\u308b<\/li>\n\n\n\n<li>\u76f8\u4e92\u306b\u6392\u4ed6\u7684\u306a\u6761\u4ef6\u306f<code>elseif<\/code>\u3092\u4f7f\u7528\u3057\u3066\u4e0d\u8981\u306a\u8a55\u4fa1\u3092\u907f\u3051\u308b<\/li>\n\n\n\n<li>\u540c\u3058\u6761\u4ef6\u3092\u8907\u6570\u56de\u8a55\u4fa1\u3057\u306a\u3044\uff08\u5909\u6570\u306b\u7d50\u679c\u3092\u4fdd\u5b58\u3059\u308b\uff09<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u52b9\u7387\u7684\u306a\u6761\u4ef6\u5206\u5c90\u306e\u4f8b\nif (empty($data)) {\n    \/\/ \u30c7\u30fc\u30bf\u304c\u7a7a\u306e\u5834\u5408\u306e\u51e6\u7406\uff08\u6700\u3082\u5358\u7d14\u306a\u30c1\u30a7\u30c3\u30af\uff09\n} elseif (empty($data['items'])) {\n    \/\/ \u30a2\u30a4\u30c6\u30e0\u304c\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\n} elseif (count($data['items']) &gt; 100) {\n    \/\/ \u30a2\u30a4\u30c6\u30e0\u304c\u591a\u3059\u304e\u308b\u5834\u5408\u306e\u51e6\u7406\uff08\u8a08\u7b97\u30b3\u30b9\u30c8\u304c\u9ad8\u3044\uff09\n} else {\n    \/\/ \u901a\u5e38\u306e\u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>\u307e\u305f\u3001PHP\u306e<code>empty()<\/code>\u7279\u6709\u306e\u6ce8\u610f\u70b9\u3068\u3057\u3066\u3001\u6570\u5024\u306e\u300c0\u300d\u3084\u6587\u5b57\u5217\u306e\u300c0\u300d\u3082\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u304c\u554f\u984c\u306b\u306a\u308b\u5834\u5408\u306f\u3001\u3088\u308a\u53b3\u5bc6\u306a\u6bd4\u8f03\u3092\u884c\u3046\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=\"\">\/\/ \u6570\u5024\u3092\u6271\u3046\u5834\u5408\u306e\u6761\u4ef6\u5206\u5c90\n$quantity = $_POST['quantity'] ?? null;\n\n\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9 - 0\u3082\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u308b\nif (empty($quantity)) {\n    echo \"\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n}\n\n\/\/ \u3088\u308a\u9069\u5207\u306a\u30b3\u30fc\u30c9\nif (!isset($quantity) || $quantity === '') {\n    echo \"\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} elseif (!is_numeric($quantity) || $quantity &lt; 0) {\n    echo \"\u6709\u52b9\u306a\u6570\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n}\n<\/pre>\n\n\n\n<p>\u6761\u4ef6\u5206\u5c90\u3067\u306e<code>empty()<\/code>\u306e\u4f7f\u7528\u306f\u3001\u9069\u5207\u306a\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3067\u884c\u3046\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u30b7\u30f3\u30d7\u30eb\u306a\u300c\u7a7a\u304b\u3069\u3046\u304b\u300d\u306e\u30c1\u30a7\u30c3\u30af\u306b\u306f\u512a\u308c\u3066\u3044\u307e\u3059\u304c\u3001\u3088\u308a\u8907\u96d1\u306a\u30ed\u30b8\u30c3\u30af\u3084\u53b3\u5bc6\u306a\u578b\u30c1\u30a7\u30c3\u30af\u304c\u5fc5\u8981\u306a\u5834\u5408\u306f\u3001\u4ed6\u306e\u65b9\u6cd5\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u304b\u3001\u30ab\u30b9\u30bf\u30e0\u95a2\u6570\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u3092\u691c\u8a0e\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-20\">\u5b9f\u8df5\u4f8b5: \u6570\u5024\u3068empty()\u306e\u610f\u5916\u306a\u95a2\u4fc2<\/h2>\n\n\n\n<p>PHP\u306e<code>empty()<\/code>\u95a2\u6570\u3068\u6570\u5024\u3068\u306e\u95a2\u4fc2\u306f\u3001\u521d\u5fc3\u8005\u3060\u3051\u3067\u306a\u304f\u7d4c\u9a13\u8c4a\u5bcc\u306a\u958b\u767a\u8005\u306b\u3068\u3063\u3066\u3082\u6df7\u4e71\u306e\u5143\u306b\u306a\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u7279\u306b\u6570\u5024\u306e\u300c0\u300d\u3068\u6587\u5b57\u5217\u306e\u300c\u201d0\u2033\u300d\u306e\u6271\u3044\u306f\u3001\u30d0\u30b0\u3092\u5f15\u304d\u8d77\u3053\u3059\u539f\u56e0\u3068\u306a\u308a\u304c\u3061\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-21\">\u6570\u50240\u3068\u6587\u5b57\u5217\u201d0\u2033\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u66d6\u6627\u3055\u3092\u89e3\u6d88\u3059\u308b<\/h3>\n\n\n\n<p><code>empty()<\/code>\u95a2\u6570\u306e\u4ed5\u69d8\u306b\u3088\u308a\u3001\u6570\u5024\u306e\u300c0\u300d\u3068\u6587\u5b57\u5217\u306e\u300c\u201d0\u2033\u300d\u306f\u4e21\u65b9\u3068\u3082\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u307e\u3059\u3002\u3053\u308c\u306f\u6642\u306b\u76f4\u611f\u306b\u53cd\u3059\u308b\u52d5\u4f5c\u3092\u3082\u305f\u3089\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=\"\">\/\/ \u6570\u5024\u3068\u6587\u5b57\u5217\u306e0\u306b\u5bfe\u3059\u308bempty()\u306e\u6319\u52d5\n$numZero = 0;\n$strZero = \"0\";\n$numPositive = 42;\n$strNumeric = \"42\";\n\nvar_dump(empty($numZero));     \/\/ bool(true) - \u6570\u5024\u306e0\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u308b\nvar_dump(empty($strZero));     \/\/ bool(true) - \u6587\u5b57\u5217\u306e\"0\"\u3082\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3055\u308c\u308b\nvar_dump(empty($numPositive)); \/\/ bool(false) - 0\u4ee5\u5916\u306e\u6570\u5024\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044\nvar_dump(empty($strNumeric));  \/\/ bool(false) - \u6570\u5024\u3092\u542b\u3080\u6587\u5b57\u5217\u306f\u300c\u7a7a\u300d\u3067\u306f\u306a\u3044\n<\/pre>\n\n\n\n<p>\u3053\u306e\u6319\u52d5\u304c\u554f\u984c\u306b\u306a\u308b\u306e\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30b1\u30fc\u30b9\u3067\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u691c\u8a3c<\/strong>\uff1a\u30e6\u30fc\u30b6\u30fc\u304c\u300c0\u300d\u3068\u5165\u529b\u3057\u305f\u5834\u5408\uff08\u6570\u91cf\u3001\u8a55\u4fa1\u306a\u3069\uff09<\/li>\n\n\n\n<li><strong>API\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u6570\u5024\u51e6\u7406<\/strong>\uff1a\u300c0\u300d\u304c\u6709\u52b9\u306a\u5024\u3067\u3042\u308b\u5834\u5408<\/li>\n\n\n\n<li><strong>\u6761\u4ef6\u5206\u5c90<\/strong>\uff1a\u5024\u304c\u300c0\u300d\u304b\u4f55\u304b\u4ed6\u306e\u5024\u304b\u3067\u51e6\u7406\u3092\u5206\u3051\u308b\u5fc5\u8981\u304c\u3042\u308b\u5834\u5408<\/li>\n<\/ol>\n\n\n\n<p>\u7279\u306b\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u3067\u306f\u3001\u5168\u3066\u306e\u5024\u304c\u6587\u5b57\u5217\u3068\u3057\u3066\u9001\u4fe1\u3055\u308c\u308b\u70b9\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30d5\u30a9\u30fc\u30e0\u304b\u3089\u9001\u4fe1\u3055\u308c\u305f\u5024\u306e\u4f8b\n$_POST['quantity'] = \"0\";  \/\/ \u30e6\u30fc\u30b6\u30fc\u304c0\u3092\u5165\u529b\u3057\u305f\u5834\u5408\n\n\/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nif (empty($_POST['quantity'])) {\n    echo \"\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\"; \/\/ \u3053\u306e\u884c\u304c\u5b9f\u884c\u3055\u308c\u308b\uff08\u610f\u56f3\u3057\u306a\u3044\u52d5\u4f5c\uff09\n}\n\n\/\/ \u6570\u91cf\u306f\u5165\u529b\u3055\u308c\u3066\u3044\u308b\u304c\u3001empty()\u306f\u300c\u7a7a\u300d\u3068\u5224\u65ad\u3057\u3066\u3057\u307e\u3046\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-22\">\u6570\u5024\u691c\u8a3c\u306e\u6b63\u3057\u3044\u30a2\u30d7\u30ed\u30fc\u30c1<\/h3>\n\n\n\n<p>\u6570\u5024\u3092\u9069\u5207\u306b\u691c\u8a3c\u3059\u308b\u305f\u3081\u306b\u306f\u3001<code>empty()<\/code>\u3060\u3051\u306b\u983c\u3089\u305a\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30a2\u30d7\u30ed\u30fc\u30c1\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\uff1a<\/p>\n\n\n\n<p><strong>1. \u5b58\u5728\u30c1\u30a7\u30c3\u30af\u3068\u5024\u30c1\u30a7\u30c3\u30af\u3092\u5206\u96e2\u3059\u308b<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u6570\u91cf\u5165\u529b\u306e\u3088\u308a\u9069\u5207\u306a\u691c\u8a3c\nif (!isset($_POST['quantity']) || $_POST['quantity'] === '') {\n    echo \"\u6570\u91cf\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} elseif (!is_numeric($_POST['quantity'])) {\n    echo \"\u6570\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} elseif ((int)$_POST['quantity'] &lt; 0) {\n    echo \"0\u4ee5\u4e0a\u306e\u6570\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} else {\n    $quantity = (int)$_POST['quantity']; \/\/ \u5b89\u5168\u306b\u578b\u5909\u63db\n    \/\/ \u51e6\u7406\u3092\u7d9a\u884c...\n}\n<\/pre>\n\n\n\n<p><strong>2. \u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u95a2\u6570\u3092\u4f7f\u7528\u3059\u308b<\/strong><\/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=\"\">\/\/ filter_var()\u3092\u4f7f\u7528\u3057\u305f\u691c\u8a3c\n$quantity = filter_var($_POST['quantity'], FILTER_VALIDATE_INT);\n\nif ($quantity === false) {\n    \/\/ \u6574\u6570\u3067\u306a\u3044\u5834\u5408\n    echo \"\u6709\u52b9\u306a\u6574\u6570\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} elseif ($quantity &lt; 0) {\n    \/\/ \u8ca0\u306e\u6570\u306e\u5834\u5408\n    echo \"0\u4ee5\u4e0a\u306e\u6570\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} else {\n    \/\/ $quantity\u306f\u691c\u8a3c\u6e08\u307f\u306e\u6574\u6570\u5024\n    \/\/ \u51e6\u7406\u3092\u7d9a\u884c...\n}\n\n\/\/ 0\u3092\u8a31\u5bb9\u3059\u308b\u5834\u5408\u306e\u6ce8\u610f\u70b9\n\/\/ filter_var(0, FILTER_VALIDATE_INT)\u306f0\u3092\u8fd4\u3059\uff08false\u3067\u306f\u306a\u3044\uff09\n<\/pre>\n\n\n\n<p><strong>3. \u578b\u3092\u610f\u8b58\u3057\u305f\u6bd4\u8f03\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\u3059\u308b<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u53b3\u5bc6\u306a\u6bd4\u8f03\u6f14\u7b97\u5b50\uff08===\uff09\u306e\u4f7f\u7528\n$value = $_POST['value'] ?? null;\n\n\/\/ \u7a7a\u6587\u5b57\u5217\u304bnull\u306e\u5834\u5408\u306e\u307f\u30a8\u30e9\u30fc\nif ($value === '' || $value === null) {\n    echo \"\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n}\n\n\/\/ 0\u3092\u8a31\u5bb9\u3059\u308b\u6761\u4ef6\u5206\u5c90\nif ($value !== null &amp;&amp; $value !== '' &amp;&amp; is_numeric($value)) {\n    $numericValue = (float)$value;\n    \/\/ \u51e6\u7406\u3092\u7d9a\u884c...\n}\n<\/pre>\n\n\n\n<p><strong>4. Null\u30c1\u30a7\u30c3\u30af\u3068\u7d44\u307f\u5408\u308f\u305b\u305f\u30d1\u30bf\u30fc\u30f3<\/strong><\/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\u3068\u578b\u30ad\u30e3\u30b9\u30c8\u306e\u7d44\u307f\u5408\u308f\u305b\n$price = isset($_POST['price']) ? (float)$_POST['price'] : null;\n\n\/\/ \u660e\u793a\u7684\u306bnull\u30680\u3092\u533a\u5225\nif ($price === null) {\n    echo \"\u4fa1\u683c\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n} elseif ($price &lt; 0) {\n    echo \"0\u4ee5\u4e0a\u306e\u4fa1\u683c\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n}\n<\/pre>\n\n\n\n<p>\u5b9f\u969b\u306e\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u4e00\u822c\u7684\u3067\u3059\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5b9f\u8df5\u7684\u306a\u6570\u5024\u691c\u8a3c\u306e\u4f8b\nfunction validateNumericInput($value, $fieldName, $allowZero = true, $allowNegative = false) {\n    $errors = [];\n    \n    \/\/ \u5165\u529b\u304c\u5b58\u5728\u3059\u308b\u304b\u30c1\u30a7\u30c3\u30af\n    if (!isset($value) || $value === '') {\n        $errors[] = \"{$fieldName}\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n        return $errors;\n    }\n    \n    \/\/ \u6570\u5024\u304b\u3069\u3046\u304b\u30c1\u30a7\u30c3\u30af\n    if (!is_numeric($value)) {\n        $errors[] = \"{$fieldName}\u306f\u6570\u5024\u3067\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n        return $errors;\n    }\n    \n    \/\/ \u6570\u5024\u306b\u5909\u63db\n    $numericValue = (float)$value;\n    \n    \/\/ 0\u306e\u8a31\u5bb9\u30c1\u30a7\u30c3\u30af\n    if ($numericValue === 0.0 &amp;&amp; !$allowZero) {\n        $errors[] = \"{$fieldName}\u306f0\u4ee5\u5916\u306e\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    \/\/ \u8ca0\u306e\u5024\u306e\u30c1\u30a7\u30c3\u30af\n    if ($numericValue &lt; 0 &amp;&amp; !$allowNegative) {\n        $errors[] = \"{$fieldName}\u306f0\u4ee5\u4e0a\u306e\u5024\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044\";\n    }\n    \n    return $errors;\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$errors = validateNumericInput($_POST['price'] ?? null, '\u4fa1\u683c');\n$errors = array_merge($errors, validateNumericInput($_POST['rating'] ?? null, '\u8a55\u4fa1', true, false));\n<\/pre>\n\n\n\n<p>\u6570\u5024\u3068<code>empty()<\/code>\u306e\u95a2\u4fc2\u3092\u6b63\u3057\u304f\u7406\u89e3\u3057\u3001\u9069\u5207\u306a\u691c\u8a3c\u65b9\u6cd5\u3092\u9078\u629e\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u69cb\u7bc9\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u7279\u306b0\u304c\u6709\u52b9\u306a\u5024\u3068\u306a\u308b\u5834\u9762\uff08\u4fa1\u683c\u3001\u6570\u91cf\u3001\u8a55\u4fa1\u306a\u3069\uff09\u3067\u306f\u3001<code>empty()<\/code>\u3060\u3051\u306b\u983c\u3089\u305a\u3001\u578b\u3092\u610f\u8b58\u3057\u305f\u691c\u8a3c\u3092\u884c\u3046\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-23\">\u5b9f\u8df5\u4f8b6: \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fempty()\u306e\u4f7f\u7528<\/h2>\n\n\n\n<p>\u5927\u898f\u6a21\u306aWeb\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3084\u30c7\u30fc\u30bf\u51e6\u7406\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u91cd\u8981\u306a\u8981\u7d20\u3068\u306a\u308a\u307e\u3059\u3002PHP\u306e<code>empty()<\/code>\u95a2\u6570\u306f\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u3067\u3059\u304c\u3001\u4f7f\u3044\u65b9\u306b\u3088\u3063\u3066\u306f\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u5168\u4f53\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001<code>empty()<\/code>\u306e\u5185\u90e8\u52d5\u4f5c\u3092\u7406\u89e3\u3057\u3001\u52b9\u7387\u7684\u306b\u4f7f\u7528\u3059\u308b\u305f\u3081\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-24\">empty()\u306e\u5185\u90e8\u52d5\u4f5c\u3068\u30e1\u30e2\u30ea\u52b9\u7387<\/h3>\n\n\n\n<p><code>empty()<\/code>\u306fPHP\u306e\u8a00\u8a9e\u69cb\u9020\uff08language construct\uff09\u3067\u3042\u308a\u3001\u901a\u5e38\u306e\u95a2\u6570\u3068\u306f\u7570\u306a\u308b\u52d5\u4f5c\u3092\u3057\u307e\u3059\u3002\u3053\u308c\u306f<code>isset()<\/code>\u3084<code>unset()<\/code>\u306a\u3069\u3068\u540c\u69d8\u306b\u3001\u8a00\u8a9e\u306e\u4e00\u90e8\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308b\u305f\u3081\u3001\u95a2\u6570\u547c\u3073\u51fa\u3057\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u3042\u308a\u307e\u305b\u3093\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=\"\">\/\/ empty()\u306f\u8a00\u8a9e\u69cb\u9020\u306e\u305f\u3081\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u62ec\u5f27\u306a\u3057\u3067\u3082\u4f7f\u7528\u3067\u304d\u308b\n\/\/ \uff08\u305f\u3060\u3057\u73fe\u4ee3\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u898f\u7d04\u3067\u306f\u975e\u63a8\u5968\uff09\nif (empty $variable) { \/* ... *\/ }  \/\/ \u6a5f\u80fd\u3059\u308b\u304c\u63a8\u5968\u3055\u308c\u306a\u3044\nif (empty($variable)) { \/* ... *\/ } \/\/ \u6a19\u6e96\u7684\u306a\u4f7f\u3044\u65b9\n<\/pre>\n\n\n\n<p>\u5185\u90e8\u7684\u306b\u306f\u3001<code>empty()<\/code>\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30ed\u30b8\u30c3\u30af\u3067\u52d5\u4f5c\u3057\u3066\u3044\u307e\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5909\u6570\u304c\u5b58\u5728\u3059\u308b\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\uff08<code>isset()<\/code>\u76f8\u5f53\uff09<\/li>\n\n\n\n<li>\u5b58\u5728\u3059\u308b\u5834\u5408\u3001\u305d\u306e\u5024\u304c\u300c\u7a7a\u300d\u3068\u3057\u3066\u5b9a\u7fa9\u3055\u308c\u308b8\u7a2e\u985e\u306e\u3044\u305a\u308c\u304b\u3068\u4e00\u81f4\u3059\u308b\u304b\u30c1\u30a7\u30c3\u30af<\/li>\n<\/ol>\n\n\n\n<p>\u3053\u306e2\u6bb5\u968e\u306e\u30d7\u30ed\u30bb\u30b9\u306f\u6700\u9069\u5316\u3055\u308c\u3066\u304a\u308a\u3001\u7279\u306b\u672a\u5b9a\u7fa9\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066\u3082\u5b89\u5168\u306b\u52d5\u4f5c\u3059\u308b\u3088\u3046\u8a2d\u8a08\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u30e1\u30e2\u30ea\u52b9\u7387\u306e\u9762\u3067\u306f\u3001<code>empty()<\/code>\u81ea\u4f53\u306f\u8ffd\u52a0\u306e\u30e1\u30e2\u30ea\u3092\u6d88\u8cbb\u305b\u305a\u3001\u5358\u306b\u5024\u306e\u8a55\u4fa1\u3092\u884c\u3046\u3060\u3051\u3067\u3059\u3002<\/p>\n\n\n\n<p><strong>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03:<\/strong><\/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=\"\">\/\/ 1,000,000\u56de\u306e\u7e70\u308a\u8fd4\u3057\u3067\u306e\u5b9f\u884c\u6642\u9593\u306e\u6bd4\u8f03\uff08\u6982\u7b97\uff09\n$start = microtime(true);\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $result = empty($var);\n}\necho \"empty(): \" . (microtime(true) - $start) . \" \u79d2\\n\";\n\n$start = microtime(true);\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $result = isset($var) &amp;&amp; $var == false;\n}\necho \"isset() &amp;&amp; == false: \" . (microtime(true) - $start) . \" \u79d2\\n\";\n\n$start = microtime(true);\nfor ($i = 0; $i &lt; 1000000; $i++) {\n    $result = $var === null || $var === '' || $var === 0 || $var === '0' || $var === false || $var === [];\n}\necho \"\u500b\u5225\u6761\u4ef6\u306e\u660e\u793a\u7684\u30c1\u30a7\u30c3\u30af: \" . (microtime(true) - $start) . \" \u79d2\\n\";\n<\/pre>\n\n\n\n<p>\u4e00\u822c\u7684\u306b\u3001<code>empty()<\/code>\u306f\u6700\u3082\u9ad8\u901f\u3067\u3059\u304c\u3001\u5177\u4f53\u7684\u306a\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5dee\u306fPHP\u306e\u30d0\u30fc\u30b8\u30e7\u30f3\u3084\u30b5\u30fc\u30d0\u30fc\u74b0\u5883\u306b\u3088\u3063\u3066\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-25\">\u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u3067\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p>\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u3001<code>empty()<\/code>\u306e\u4f7f\u7528\u65b9\u6cd5\u306b\u3088\u3063\u3066\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u5927\u304d\u304f\u5909\u308f\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u4ee5\u4e0b\u306b\u3001\u3044\u304f\u3064\u304b\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p><strong>1. \u30eb\u30fc\u30d7\u5185\u3067\u306e\u30ad\u30e3\u30c3\u30b7\u30e5<\/strong><\/p>\n\n\n\n<p>\u30eb\u30fc\u30d7\u5185\u3067\u540c\u3058\u5024\u3084\u5f0f\u3092\u7e70\u308a\u8fd4\u3057<code>empty()<\/code>\u3067\u30c1\u30a7\u30c3\u30af\u3059\u308b\u306e\u306f\u975e\u52b9\u7387\u7684\u3067\u3059\u3002\u4ee3\u308f\u308a\u306b\u3001\u7d50\u679c\u3092\u30ad\u30e3\u30c3\u30b7\u30e5\u3057\u3066\u518d\u5229\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u975e\u52b9\u7387\u306a\u4f8b\nforeach ($items as $item) {\n    if (!empty($config['debug_mode'])) {\n        \/\/ \u30c7\u30d0\u30c3\u30b0\u30e2\u30fc\u30c9\u306e\u51e6\u7406\n    }\n    \/\/ \u305d\u306e\u4ed6\u306e\u51e6\u7406...\n}\n\n\/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u4f8b\n$debugModeEnabled = !empty($config['debug_mode']);\nforeach ($items as $item) {\n    if ($debugModeEnabled) {\n        \/\/ \u30c7\u30d0\u30c3\u30b0\u30e2\u30fc\u30c9\u306e\u51e6\u7406\n    }\n    \/\/ \u305d\u306e\u4ed6\u306e\u51e6\u7406...\n}\n<\/pre>\n\n\n\n<p><strong>2. \u5927\u304d\u306a\u914d\u5217\u3084\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u306e\u52b9\u7387\u7684\u306a\u51e6\u7406<\/strong><\/p>\n\n\n\n<p>\u5927\u304d\u306a\u914d\u5217\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u3001\u5168\u4f53\u306b\u5bfe\u3057\u3066<code>empty()<\/code>\u3092\u30c1\u30a7\u30c3\u30af\u3057\u3066\u304b\u3089\u51e6\u7406\u3092\u59cb\u3081\u308b\u3068\u52b9\u7387\u7684\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=\"\">\/\/ \u5927\u304d\u306a\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u306e\u51e6\u7406\u4f8b\nfunction processLargeDataset($data) {\n    \/\/ \u6700\u521d\u306b\u7a7a\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\n    if (empty($data)) {\n        return [];\n    }\n    \n    \/\/ \u6b21\u306b\u30c7\u30fc\u30bf\u304c\u914d\u5217\u304b\u3069\u3046\u304b\u78ba\u8a8d\n    if (!is_array($data)) {\n        throw new InvalidArgumentException('\u914d\u5217\u304c\u671f\u5f85\u3055\u308c\u3066\u3044\u307e\u3059');\n    }\n    \n    $result = [];\n    \n    \/\/ \u30c7\u30fc\u30bf\u306e\u51e6\u7406\uff08\u30c1\u30e3\u30f3\u30af\u5358\u4f4d\u3067\uff09\n    $chunks = array_chunk($data, 1000);\n    foreach ($chunks as $chunk) {\n        $result = array_merge($result, processChunk($chunk));\n    }\n    \n    return $result;\n}\n<\/pre>\n\n\n\n<p><strong>3. \u6761\u4ef6\u8a55\u4fa1\u306e\u6700\u9069\u5316<\/strong><\/p>\n\n\n\n<p>\u8907\u6570\u306e\u6761\u4ef6\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u5834\u5408\u3001\u8a55\u4fa1\u9806\u5e8f\u3092\u8003\u616e\u3059\u308b\u3053\u3068\u3067\u51e6\u7406\u3092\u52b9\u7387\u5316\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u8a08\u7b97\u30b3\u30b9\u30c8\u306e\u9ad8\u3044\u64cd\u4f5c\u306f\u5f8c\u56de\u3057\u306b\u3059\u308b\nfunction isValidRecord($record) {\n    \/\/ \u307e\u305a\u57fa\u672c\u7684\u306a\u691c\u8a3c\uff08\u8efd\u91cf\uff09\n    if (empty($record)) {\n        return false;\n    }\n    \n    \/\/ \u6b21\u306b\u5fc5\u9808\u30ad\u30fc\u306e\u5b58\u5728\u78ba\u8a8d\n    if (empty($record['id']) || empty($record['type'])) {\n        return false;\n    }\n    \n    \/\/ \u6700\u5f8c\u306b\u3088\u308a\u8a08\u7b97\u30b3\u30b9\u30c8\u306e\u9ad8\u3044\u691c\u8a3c\n    if ($record['type'] === 'special' &amp;&amp; !validateSpecialRecord($record)) {\n        return false;\n    }\n    \n    return true;\n}\n<\/pre>\n\n\n\n<p><strong>4. \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30af\u30a8\u30ea\u3068\u306e\u7d44\u307f\u5408\u308f\u305b<\/strong><\/p>\n\n\n\n<p>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u3089\u306e\u7d50\u679c\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u3001<code>empty()<\/code>\u3092\u4f7f\u3063\u3066\u52b9\u7387\u7684\u306b\u30c1\u30a7\u30c3\u30af\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u7d50\u679c\u306e\u52b9\u7387\u7684\u306a\u51e6\u7406\n$stmt = $pdo-&gt;prepare(\"SELECT * FROM users WHERE status = ?\");\n$stmt-&gt;execute(['active']);\n$users = $stmt-&gt;fetchAll(PDO::FETCH_ASSOC);\n\n\/\/ \u7d50\u679c\u304c\u7a7a\u304b\u3069\u3046\u304b\u3092\u4e00\u5ea6\u3060\u3051\u30c1\u30a7\u30c3\u30af\nif (empty($users)) {\n    echo \"\u30a2\u30af\u30c6\u30a3\u30d6\u306a\u30e6\u30fc\u30b6\u30fc\u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\u3067\u3057\u305f\";\n    return;\n}\n\n\/\/ \u7d50\u679c\u304c\u5b58\u5728\u3059\u308b\u3053\u3068\u304c\u78ba\u8a8d\u3067\u304d\u305f\u306e\u3067\u51e6\u7406\u3092\u7d9a\u884c\nforeach ($users as $user) {\n    \/\/ \u5404\u30e6\u30fc\u30b6\u30fc\u306e\u51e6\u7406...\n}\n<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316\u3059\u308b\u969b\u306e\u4e00\u822c\u7684\u306a\u539f\u5247\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u4e0d\u8981\u306a\u8a55\u4fa1\u3092\u907f\u3051\u308b<\/strong>: \u540c\u3058\u6761\u4ef6\u3092\u7e70\u308a\u8fd4\u3057\u30c1\u30a7\u30c3\u30af\u3057\u306a\u3044<\/li>\n\n\n\n<li><strong>\u8efd\u91cf\u306a\u6761\u4ef6\u3092\u5148\u306b\u8a55\u4fa1<\/strong>: \u8a08\u7b97\u30b3\u30b9\u30c8\u306e\u4f4e\u3044\u6761\u4ef6\u3092\u5148\u306b\u30c1\u30a7\u30c3\u30af\u3059\u308b<\/li>\n\n\n\n<li><strong>\u30d0\u30c3\u30c1\u51e6\u7406\u3092\u6d3b\u7528<\/strong>: \u5927\u91cf\u30c7\u30fc\u30bf\u306f\u9069\u5207\u306a\u30b5\u30a4\u30ba\u306e\u30c1\u30e3\u30f3\u30af\u306b\u5206\u3051\u3066\u51e6\u7406\u3059\u308b<\/li>\n\n\n\n<li><strong>\u7d50\u679c\u3092\u30ad\u30e3\u30c3\u30b7\u30e5\u3059\u308b<\/strong>: \u7e70\u308a\u8fd4\u3057\u4f7f\u7528\u3059\u308b\u5024\u306f\u5909\u6570\u306b\u4fdd\u5b58\u3059\u308b<\/li>\n\n\n\n<li><strong>\u8a00\u8a9e\u69cb\u9020\u3092\u6d3b\u7528\u3059\u308b<\/strong>: <code>empty()<\/code>\u3084<code>isset()<\/code>\u306f\u4e00\u822c\u7684\u306a\u95a2\u6570\u3088\u308a\u3082\u9ad8\u901f<\/li>\n<\/ol>\n\n\n\n<p><code>empty()<\/code>\u95a2\u6570\u306f\u5c0f\u3055\u306a\u6700\u9069\u5316\u3067\u3059\u304c\u3001\u7279\u306b\u9ad8\u30c8\u30e9\u30d5\u30a3\u30c3\u30af\u306e\u30a6\u30a7\u30d6\u30b5\u30a4\u30c8\u3084\u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u3092\u884c\u3046\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u3046\u3057\u305f\u6700\u9069\u5316\u306e\u7a4d\u307f\u91cd\u306d\u304c\u5168\u4f53\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u5927\u304d\u304f\u5de6\u53f3\u3057\u307e\u3059\u3002\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u5fdc\u7b54\u6027\u306e\u9ad8\u3044\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u69cb\u7bc9\u3067\u304d\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-26\">\u5b9f\u8df5\u4f8b7: \u30bb\u30ad\u30e5\u30a2\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3068empty()<\/h2>\n\n\n\n<p>\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u306fWeb\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u306b\u304a\u3044\u3066\u6700\u3082\u91cd\u8981\u306a\u5074\u9762\u306e\u4e00\u3064\u3067\u3059\u3002PHP\u306e<code>empty()<\/code>\u95a2\u6570\u306f\u30b7\u30f3\u30d7\u30eb\u3067\u3059\u304c\u3001\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u5bfe\u7b56\u306e\u4e00\u90e8\u3068\u3057\u3066\u6a5f\u80fd\u3057\u307e\u3059\u3002\u305f\u3060\u3057\u3001<code>empty()<\/code>\u3060\u3051\u3067\u306f\u5341\u5206\u306a\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u3092\u78ba\u4fdd\u3067\u304d\u306a\u3044\u3053\u3068\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-27\">\u5916\u90e8\u5165\u529b\u30c7\u30fc\u30bf\u3092\u691c\u8a3c\u3059\u308b\u969b\u306e\u5b89\u5168\u5bfe\u7b56<\/h3>\n\n\n\n<p>\u5916\u90e8\u304b\u3089\u306e\u5165\u529b\uff08\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3001API\u30ec\u30b9\u30dd\u30f3\u30b9\u3001\u30d5\u30a1\u30a4\u30eb\u30a2\u30c3\u30d7\u30ed\u30fc\u30c9\u306a\u3069\uff09\u306f\u3001\u5e38\u306b\u6f5c\u5728\u7684\u306a\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u30ea\u30b9\u30af\u3068\u3057\u3066\u6271\u3046\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<code>empty()<\/code>\u306f\u3053\u308c\u3089\u306e\u5165\u529b\u3092\u691c\u8a3c\u3059\u308b\u6700\u521d\u306e\u30b9\u30c6\u30c3\u30d7\u3068\u3057\u3066\u5f79\u7acb\u3061\u307e\u3059\u304c\u3001\u305d\u308c\u3060\u3051\u3067\u306f\u4e0d\u5341\u5206\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=\"\">\/\/ \u57fa\u672c\u7684\u306a\u5165\u529b\u691c\u8a3c\u306e\u4f8b\nif (empty($_POST['username'])) {\n    $errors[] = '\u30e6\u30fc\u30b6\u30fc\u540d\u306f\u5fc5\u9808\u3067\u3059';\n} elseif (!preg_match('\/^[a-zA-Z0-9_]{3,16}$\/', $_POST['username'])) {\n    $errors[] = '\u30e6\u30fc\u30b6\u30fc\u540d\u306f3\u301c16\u6587\u5b57\u306e\u82f1\u6570\u5b57\u3068\u30a2\u30f3\u30c0\u30fc\u30b9\u30b3\u30a2\u306e\u307f\u4f7f\u7528\u3067\u304d\u307e\u3059';\n}\n\n\/\/ \u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306e\u691c\u8a3c\u4f8b\nif (empty($_POST['email'])) {\n    $errors[] = '\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306f\u5fc5\u9808\u3067\u3059';\n} elseif (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {\n    $errors[] = '\u6709\u52b9\u306a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n}\n<\/pre>\n\n\n\n<p>\u30bb\u30ad\u30e5\u30a2\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3067\u306f\u3001\u4ee5\u4e0b\u306e\u539f\u5247\u306b\u5f93\u3063\u3066<code>empty()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u5b58\u5728\u30c1\u30a7\u30c3\u30af\u3068\u691c\u8a3c\u306e\u5206\u96e2<\/strong>: <code>empty()<\/code>\u3067\u5024\u306e\u5b58\u5728\u3092\u30c1\u30a7\u30c3\u30af\u3057\u305f\u5f8c\u3001\u5225\u306e\u65b9\u6cd5\u3067\u5024\u306e\u59a5\u5f53\u6027\u3092\u691c\u8a3c\u3059\u308b<\/li>\n\n\n\n<li><strong>\u9069\u5207\u306a\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3067\u306e\u4f7f\u7528<\/strong>: \u6587\u8108\u306b\u5fdc\u3058\u3066<code>empty()<\/code>\u3068\u4ed6\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u624b\u6cd5\u3092\u7d44\u307f\u5408\u308f\u305b\u308b<\/li>\n\n\n\n<li><strong>\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u306e\u9069\u5207\u306a\u8a2d\u8a08<\/strong>: \u6280\u8853\u7684\u306a\u8a73\u7d30\u3092\u660e\u304b\u3055\u306a\u3044\u5b89\u5168\u306a\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u3092\u8003\u616e\u3057\u305f\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u306e\u4f8b\nfunction processUserInput($input) {\n    $safeData = [];\n    $errors = [];\n    \n    \/\/ \u30e6\u30fc\u30b6\u30fc\u540d\u306e\u691c\u8a3c\n    if (empty($input['username'])) {\n        $errors['username'] = '\u5fc5\u9808\u9805\u76ee\u3067\u3059';\n    } elseif (!preg_match('\/^[a-zA-Z0-9_]{3,16}$\/', $input['username'])) {\n        $errors['username'] = '\u7121\u52b9\u306a\u5f62\u5f0f\u3067\u3059';\n    } else {\n        $safeData['username'] = htmlspecialchars($input['username'], ENT_QUOTES, 'UTF-8');\n    }\n    \n    \/\/ \u30d1\u30b9\u30ef\u30fc\u30c9\u306e\u691c\u8a3c\n    if (empty($input['password'])) {\n        $errors['password'] = '\u5fc5\u9808\u9805\u76ee\u3067\u3059';\n    } elseif (strlen($input['password']) &lt; 8) {\n        $errors['password'] = '8\u6587\u5b57\u4ee5\u4e0a\u5fc5\u8981\u3067\u3059';\n    } else {\n        \/\/ \u30d1\u30b9\u30ef\u30fc\u30c9\u306f\u30cf\u30c3\u30b7\u30e5\u5316\u3057\u3066\u4fdd\u5b58\n        $safeData['password'] = password_hash($input['password'], PASSWORD_DEFAULT);\n    }\n    \n    \/\/ \u4ed6\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u3082\u540c\u69d8\u306b\u691c\u8a3c...\n    \n    return ['data' =&gt; $safeData, 'errors' =&gt; $errors];\n}\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-28\">\u578b\u306e\u53b3\u5bc6\u306a\u691c\u8a3c\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u30ed\u30d0\u30b9\u30c8\u306a\u5b9f\u88c5\u4f8b<\/h3>\n\n\n\n<p><code>empty()<\/code>\u3068\u578b\u306e\u53b3\u5bc6\u306a\u691c\u8a3c\u3092\u7d44\u307f\u5408\u308f\u305b\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\u306bPHP 7\u4ee5\u964d\u3067\u306f\u3001\u578b\u5ba3\u8a00\uff08\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\uff09\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u304c\u63a8\u5968\u3055\u308c\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=\"\">\/**\n * \u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3092\u5b89\u5168\u306b\u51e6\u7406\u3059\u308b\u30af\u30e9\u30b9\u306e\u4f8b\n *\/\nclass InputValidator {\n    \/**\n     * \u6574\u6570\u5024\u3092\u691c\u8a3c\u3057\u3066\u8fd4\u3059\n     * @param mixed $value \u691c\u8a3c\u3059\u308b\u5024\n     * @param int $min \u6700\u5c0f\u5024\n     * @param int $max \u6700\u5927\u5024\n     * @return int|null \u691c\u8a3c\u6e08\u307f\u306e\u6574\u6570\u307e\u305f\u306f\u7121\u52b9\u306a\u5834\u5408\u306fnull\n     *\/\n    public function validateInteger($value, int $min = PHP_INT_MIN, int $max = PHP_INT_MAX): ?int {\n        if (empty($value) &amp;&amp; $value !== '0' &amp;&amp; $value !== 0) {\n            return null;\n        }\n        \n        \/\/ \u6574\u6570\u30c1\u30a7\u30c3\u30af\n        $filtered = filter_var($value, FILTER_VALIDATE_INT);\n        if ($filtered === false) {\n            return null;\n        }\n        \n        \/\/ \u7bc4\u56f2\u30c1\u30a7\u30c3\u30af\n        if ($filtered &lt; $min || $filtered &gt; $max) {\n            return null;\n        }\n        \n        return $filtered;\n    }\n    \n    \/**\n     * \u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u691c\u8a3c\u3057\u3066\u8fd4\u3059\n     * @param mixed $value \u691c\u8a3c\u3059\u308b\u5024\n     * @return string|null \u691c\u8a3c\u6e08\u307f\u306e\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u307e\u305f\u306f\u7121\u52b9\u306a\u5834\u5408\u306fnull\n     *\/\n    public function validateEmail($value): ?string {\n        if (empty($value)) {\n            return null;\n        }\n        \n        $filtered = filter_var($value, FILTER_VALIDATE_EMAIL);\n        if ($filtered === false) {\n            return null;\n        }\n        \n        return $filtered;\n    }\n    \n    \/**\n     * SQL\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u5bfe\u7b56\u306e\u305f\u3081\u306e\u5b89\u5168\u306a\u6587\u5b57\u5217\u3092\u8fd4\u3059\n     * @param mixed $value \u691c\u8a3c\u3059\u308b\u5024\n     * @param int $maxLength \u6700\u5927\u9577\n     * @return string|null \u691c\u8a3c\u6e08\u307f\u306e\u6587\u5b57\u5217\u307e\u305f\u306f\u7121\u52b9\u306a\u5834\u5408\u306fnull\n     *\/\n    public function validateString($value, int $maxLength = 255): ?string {\n        if (empty($value) &amp;&amp; $value !== '0') {\n            return null;\n        }\n        \n        \/\/ \u6587\u5b57\u5217\u578b\u3092\u5f37\u5236\n        $stringValue = (string)$value;\n        \n        \/\/ \u9577\u3055\u30c1\u30a7\u30c3\u30af\n        if (mb_strlen($stringValue) &gt; $maxLength) {\n            return null;\n        }\n        \n        \/\/ HTML\u30a8\u30b9\u30b1\u30fc\u30d7\uff08XSS\u5bfe\u7b56\uff09\n        return htmlspecialchars($stringValue, ENT_QUOTES, 'UTF-8');\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\n$validator = new InputValidator();\n$userId = $validator-&gt;validateInteger($_GET['user_id'] ?? null, 1);\n$email = $validator-&gt;validateEmail($_POST['email'] ?? null);\n$comment = $validator-&gt;validateString($_POST['comment'] ?? null, 1000);\n\n\/\/ \u691c\u8a3c\u7d50\u679c\u306b\u57fa\u3065\u3044\u305f\u51e6\u7406\nif ($userId !== null &amp;&amp; $email !== null) {\n    \/\/ \u5b89\u5168\u306b\u51e6\u7406\u3092\u5b9f\u884c\n    processUserData($userId, $email, $comment);\n} else {\n    \/\/ \u30a8\u30e9\u30fc\u51e6\u7406\n    handleValidationError();\n}\n<\/pre>\n\n\n\n<p>\u30bb\u30ad\u30e5\u30a2\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3067\u306f\u3001\u4ee5\u4e0b\u306e\u70b9\u306b\u7279\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>SQL\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u5bfe\u7b56<\/strong>: <code>empty()<\/code>\u3067\u306e\u30c1\u30a7\u30c3\u30af\u5f8c\u3001\u30d7\u30ea\u30da\u30a2\u30c9\u30b9\u30c6\u30fc\u30c8\u30e1\u30f3\u30c8\u3092\u4f7f\u7528\u3059\u308b<\/li>\n\n\n\n<li><strong>XSS\u5bfe\u7b56<\/strong>: \u51fa\u529b\u524d\u306b\u9069\u5207\u306bHTML\u30a8\u30b9\u30b1\u30fc\u30d7\u3059\u308b<\/li>\n\n\n\n<li><strong>CSRF\u30c8\u30fc\u30af\u30f3<\/strong>: \u30d5\u30a9\u30fc\u30e0\u9001\u4fe1\u306b\u5bfe\u3057\u3066\u30c8\u30fc\u30af\u30f3\u3092\u691c\u8a3c\u3059\u308b<\/li>\n\n\n\n<li><strong>\u30d5\u30a1\u30a4\u30eb\u30a2\u30c3\u30d7\u30ed\u30fc\u30c9<\/strong>: MIME\u30bf\u30a4\u30d7\u3084\u30b5\u30a4\u30ba\u306e\u691c\u8a3c\u3092\u53b3\u5bc6\u306b\u884c\u3046<\/li>\n\n\n\n<li><strong>\u30bb\u30c3\u30b7\u30e7\u30f3<\/strong>: \u30bb\u30c3\u30b7\u30e7\u30f3\u30c7\u30fc\u30bf\u306e\u691c\u8a3c\u3092\u53b3\u683c\u306b\u884c\u3046<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ SQL\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u5bfe\u7b56\u306e\u4f8b\n$userId = !empty($_GET['id']) ? (int)$_GET['id'] : 0;\nif ($userId &gt; 0) {\n    $stmt = $pdo-&gt;prepare(\"SELECT * FROM users WHERE id = ?\");\n    $stmt-&gt;execute([$userId]);\n    $user = $stmt-&gt;fetch(PDO::FETCH_ASSOC);\n} else {\n    \/\/ \u7121\u52b9\u306aID\n}\n\n\/\/ XSS\u5bfe\u7b56\u306e\u4f8b\n$username = !empty($_POST['username']) ? htmlspecialchars($_POST['username'], ENT_QUOTES, 'UTF-8') : '';\necho \"\u3088\u3046\u3053\u305d\u3001{$username}\u3055\u3093\";\n<\/pre>\n\n\n\n<p><code>empty()<\/code>\u306f\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u5bfe\u7b56\u306e\u4e00\u90e8\u3068\u3057\u3066\u306f\u6709\u7528\u3067\u3059\u304c\u3001\u5b8c\u5168\u306a\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u30bd\u30ea\u30e5\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u306a\u3044\u3053\u3068\u3092\u7406\u89e3\u3057\u3001\u5e38\u306b\u8907\u6570\u306e\u691c\u8a3c\u30ec\u30a4\u30e4\u30fc\u3092\u5b9f\u88c5\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u9069\u5207\u306a\u578b\u30c1\u30a7\u30c3\u30af\u3001\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u3001\u30a8\u30b9\u30b1\u30fc\u30d7\u51e6\u7406\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5b89\u5168\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u69cb\u7bc9\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-29\">empty()\u95a2\u6570\u3092\u4f7f\u3044\u3053\u306a\u3059\u305f\u3081\u306e7\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n\n\n\n<p>\u3053\u3053\u307e\u3067<code>empty()<\/code>\u95a2\u6570\u306e\u57fa\u790e\u304b\u3089\u5b9f\u8df5\u7684\u306a\u4f7f\u7528\u4f8b\u307e\u3067\u898b\u3066\u304d\u307e\u3057\u305f\u3002\u6700\u5f8c\u306b\u3001<code>empty()<\/code>\u3092\u52b9\u679c\u7684\u306b\u4f7f\u3044\u3053\u306a\u3059\u305f\u3081\u306e7\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u307e\u3068\u3081\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u65e5\u3005\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u306b\u53d6\u308a\u5165\u308c\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044PHP\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-30\">\u53ef\u8aad\u6027\u3092\u9ad8\u3081\u308b\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b9\u30bf\u30a4\u30eb<\/h3>\n\n\n\n<p>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u306f\u3001\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u6027\u3084\u54c1\u8cea\u306b\u76f4\u7d50\u3059\u308b\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002<code>empty()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u969b\u3082\u3001\u53ef\u8aad\u6027\u3092\u610f\u8b58\u3057\u305f\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3092\u5fc3\u304c\u3051\u307e\u3057\u3087\u3046\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=\"\">\/\/ \u53ef\u8aad\u6027\u306e\u4f4e\u3044\u30b3\u30fc\u30c9\nif(!empty($user)&amp;&amp;!empty($user['permissions'])&amp;&amp;!empty($user['permissions']['admin'])){\n    \/\/ \u7ba1\u7406\u8005\u51e6\u7406\n}\n\n\/\/ \u53ef\u8aad\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\nif (\n    !empty($user) &amp;&amp;\n    !empty($user['permissions']) &amp;&amp;\n    !empty($user['permissions']['admin'])\n) {\n    \/\/ \u7ba1\u7406\u8005\u51e6\u7406\n}\n\n\/\/ \u3055\u3089\u306b\u6539\u5584\u3057\u305f\u30b3\u30fc\u30c9\n$isAdmin = !empty($user) &amp;&amp;\n           !empty($user['permissions']) &amp;&amp;\n           !empty($user['permissions']['admin']);\n\nif ($isAdmin) {\n    \/\/ \u7ba1\u7406\u8005\u51e6\u7406\n}\n<\/pre>\n\n\n\n<p>\u53ef\u8aad\u6027\u3092\u9ad8\u3081\u308b\u305f\u3081\u306e\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u9069\u5207\u306a\u30a4\u30f3\u30c7\u30f3\u30c8\u3068\u6539\u884c<\/strong>: \u8907\u6570\u306e\u6761\u4ef6\u3092\u6301\u3064\u5834\u5408\u306f\u3001\u6539\u884c\u3068\u30a4\u30f3\u30c7\u30f3\u30c8\u3067\u69cb\u9020\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n\n\n\n<li><strong>\u8aac\u660e\u7684\u306a\u5909\u6570\u540d<\/strong>: \u8907\u96d1\u306a\u6761\u4ef6\u306f\u4e2d\u9593\u5909\u6570\u306b\u4ee3\u5165\u3057\u3001\u305d\u306e\u610f\u56f3\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n\n\n\n<li><strong>\u4e00\u8cab\u6027\u306e\u3042\u308b\u8a18\u8ff0\u30d1\u30bf\u30fc\u30f3<\/strong>: \u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5185\u3067<code>empty()<\/code>\u306e\u4f7f\u7528\u30d1\u30bf\u30fc\u30f3\u3092\u7d71\u4e00\u3059\u308b<\/li>\n\n\n\n<li><strong>PHPDoc\u30b3\u30e1\u30f3\u30c8<\/strong>: \u8907\u96d1\u306a\u30ed\u30b8\u30c3\u30af\u306b\u306f\u9069\u5207\u306a\u30b3\u30e1\u30f3\u30c8\u3092\u8ffd\u52a0\u3059\u308b<\/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=\"\">\/**\n * \u30e6\u30fc\u30b6\u30fc\u304c\u7ba1\u7406\u8005\u6a29\u9650\u3092\u6301\u3063\u3066\u3044\u308b\u304b\u30c1\u30a7\u30c3\u30af\u3059\u308b\n *\n * @param array|null $user \u30e6\u30fc\u30b6\u30fc\u30c7\u30fc\u30bf\u914d\u5217\n * @return bool \u7ba1\u7406\u8005\u6a29\u9650\u304c\u3042\u308b\u5834\u5408\u306ftrue\n *\/\nfunction isAdmin(?array $user): bool\n{\n    return !empty($user) &amp;&amp;\n           !empty($user['permissions']) &amp;&amp;\n           !empty($user['permissions']['admin']);\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nif (isAdmin($currentUser)) {\n    \/\/ \u7ba1\u7406\u8005\u51e6\u7406\n}\n<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-31\">\u30e6\u30cb\u30c3\u30c8\u30c6\u30b9\u30c8\u3067\u306eempty()\u306e\u30c6\u30b9\u30c8\u65b9\u6cd5<\/h3>\n\n\n\n<p><code>empty()<\/code>\u3092\u4f7f\u7528\u3057\u305f\u30b3\u30fc\u30c9\u306e\u30c6\u30b9\u30c8\u306f\u3001\u3055\u307e\u3056\u307e\u306a\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u8003\u616e\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002PHPUnit\u3092\u4f7f\u7528\u3057\u305f\u57fa\u672c\u7684\u306a\u30c6\u30b9\u30c8\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">use PHPUnit\\Framework\\TestCase;\n\nclass UserValidatorTest extends TestCase\n{\n    \/**\n     * @dataProvider emptyValueProvider\n     *\/\n    public function testIsEmptyDetectsEmptyValues($value, $expected)\n    {\n        $validator = new UserValidator();\n        $this-&gt;assertSame($expected, $validator-&gt;isEmpty($value));\n    }\n    \n    public function emptyValueProvider()\n    {\n        return [\n            'null' =&gt; [null, true],\n            'empty string' =&gt; ['', true],\n            'zero as integer' =&gt; [0, true],\n            'zero as string' =&gt; ['0', true],\n            'false' =&gt; [false, true],\n            'empty array' =&gt; [[], true],\n            'non-empty string' =&gt; ['text', false],\n            'positive number' =&gt; [42, false],\n            'array with elements' =&gt; [[1, 2, 3], false],\n        ];\n    }\n    \n    public function testFormValidation()\n    {\n        $validator = new UserValidator();\n        \n        \/\/ \u7a7a\u306e\u30c7\u30fc\u30bf\u306e\u30c6\u30b9\u30c8\n        $emptyData = [];\n        $result = $validator-&gt;validateForm($emptyData);\n        $this-&gt;assertFalse($result['valid']);\n        $this-&gt;assertNotEmpty($result['errors']['username']);\n        \n        \/\/ \u6709\u52b9\u306a\u30c7\u30fc\u30bf\u306e\u30c6\u30b9\u30c8\n        $validData = ['username' =&gt; 'john_doe', 'email' =&gt; 'john@example.com'];\n        $result = $validator-&gt;validateForm($validData);\n        $this-&gt;assertTrue($result['valid']);\n        $this-&gt;assertEmpty($result['errors']);\n    }\n}\n<\/pre>\n\n\n\n<p><code>empty()<\/code>\u3092\u30c6\u30b9\u30c8\u3059\u308b\u969b\u306e\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30c7\u30fc\u30bf\u30d7\u30ed\u30d0\u30a4\u30c0\u306e\u6d3b\u7528<\/strong>: \u3055\u307e\u3056\u307e\u306a\u5165\u529b\u5024\u3068\u305d\u306e\u671f\u5f85\u3055\u308c\u308b\u7d50\u679c\u3092\u7db2\u7f85\u7684\u306b\u30c6\u30b9\u30c8\u3059\u308b<\/li>\n\n\n\n<li><strong>\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u306e\u30c6\u30b9\u30c8<\/strong>: \u7279\u306b\u6570\u5024\u306e<code>0<\/code>\u3084\u6587\u5b57\u5217\u306e<code>\"0\"<\/code>\u306a\u3069\u3001\u8aa4\u308a\u3084\u3059\u3044\u30b1\u30fc\u30b9\u3092\u660e\u793a\u7684\u306b\u30c6\u30b9\u30c8<\/li>\n\n\n\n<li><strong>\u7d71\u5408\u30c6\u30b9\u30c8<\/strong>: \u30d5\u30a9\u30fc\u30e0\u691c\u8a3c\u306a\u3069\u306e\u5b9f\u969b\u306e\u4f7f\u7528\u30b7\u30fc\u30f3\u3082\u542b\u3081\u3066\u30c6\u30b9\u30c8\u3059\u308b<\/li>\n\n\n\n<li><strong>\u30e2\u30c3\u30af\u306e\u6d3b\u7528<\/strong>: \u5916\u90e8\u4f9d\u5b58\uff08\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306a\u3069\uff09\u304c\u3042\u308b\u5834\u5408\u306f\u30e2\u30c3\u30af\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-32\">\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\u3068\u52b9\u679c\u7684\u306a\u4f75\u7528<\/h3>\n\n\n\n<p>PHP 7\u4ee5\u964d\u3067\u306f\u3001\u578b\u5ba3\u8a00\uff08\u30bf\u30a4\u30d7\u30d2\u30f3\u30c6\u30a3\u30f3\u30b0\uff09\u304c\u5f37\u5316\u3055\u308c\u3001\u3088\u308a\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002<code>empty()<\/code>\u3068\u578b\u5ba3\u8a00\u3092\u52b9\u679c\u7684\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3055\u3089\u306b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\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=\"\">\/**\n * User entity class with type declarations\n *\/\nclass User\n{\n    public function __construct(\n        private int $id,\n        private string $username,\n        private ?string $email = null,\n        private array $roles = []\n    ) {}\n    \n    public function getEmail(): ?string\n    {\n        return $this-&gt;email;\n    }\n    \n    public function hasEmail(): bool\n    {\n        return !empty($this-&gt;email);\n    }\n    \n    public function hasRole(string $role): bool\n    {\n        return !empty($this-&gt;roles) &amp;&amp; in_array($role, $this-&gt;roles);\n    }\n}\n\n\/**\n * Email sending service with type declarations\n *\/\nclass EmailService\n{\n    \/**\n     * Send email to user if they have an email address\n     *\/\n    public function sendNotification(User $user, string $message): bool\n    {\n        if (empty($user) || !$user-&gt;hasEmail()) {\n            return false;\n        }\n        \n        $email = $user-&gt;getEmail();\n        \/\/ Here we can safely use $email because we checked with hasEmail()\n        \/\/ and we know from the return type it's either string or null\n        \n        \/\/ Send email logic...\n        return true;\n    }\n}\n<\/pre>\n\n\n\n<p>\u578b\u5ba3\u8a00\u3068<code>empty()<\/code>\u3092\u4f75\u7528\u3059\u308b\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Nullable\u578b\u306e\u6d3b\u7528<\/strong>: <code>?string<\/code>\u306e\u3088\u3046\u306b\u3001null\u3092\u8a31\u5bb9\u3059\u308b\u578b\u3092\u660e\u793a\u3059\u308b<\/li>\n\n\n\n<li><strong>\u8fd4\u308a\u5024\u306e\u578b\u5ba3\u8a00<\/strong>: \u30e1\u30bd\u30c3\u30c9\u306e\u8fd4\u308a\u5024\u306e\u578b\u3092\u660e\u78ba\u306b\u3059\u308b<\/li>\n\n\n\n<li><strong>\u53b3\u683c\u306a\u578b\u30c1\u30a7\u30c3\u30af<\/strong>: <code>declare(strict_types=1);<\/code>\u3092\u4f7f\u7528\u3057\u3066\u578b\u30c1\u30a7\u30c3\u30af\u3092\u53b3\u683c\u306b\u3059\u308b<\/li>\n\n\n\n<li><strong>\u30d8\u30eb\u30d1\u30fc\u30e1\u30bd\u30c3\u30c9\u306e\u4f5c\u6210<\/strong>: \u8907\u96d1\u306a\u7a7a\u30c1\u30a7\u30c3\u30af\u306f\u30e1\u30bd\u30c3\u30c9\u306b\u62bd\u51fa\u3059\u308b<\/li>\n\n\n\n<li><strong>PHPDoc\u3068\u306e\u4f75\u7528<\/strong>: \u578b\u5ba3\u8a00\u3060\u3051\u3067\u306a\u304f\u3001\u8a73\u7d30\u306a\u60c5\u5831\u3092PHPDoc\u3067\u88dc\u5b8c\u3059\u308b<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-33\">\u305d\u306e\u4ed6\u306e4\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-34\">1. \u76ee\u7684\u306b\u5408\u3063\u305f\u95a2\u6570\u306e\u9078\u629e<\/h4>\n\n\n\n<p>\u305d\u308c\u305e\u308c\u306e\u95a2\u6570\u306e\u7279\u6027\u3092\u7406\u89e3\u3057\u3001\u76ee\u7684\u306b\u5408\u3063\u305f\u95a2\u6570\u3092\u9078\u629e\u3057\u307e\u3057\u3087\u3046\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\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif (isset($var)) { \/* ... *\/ }\n\n\/\/ \u5909\u6570\u304cnull\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif (is_null($var)) { \/* ... *\/ }\n\n\/\/ \u5909\u6570\u304c\u300c\u7a7a\u300d\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif (empty($var)) { \/* ... *\/ }\n\n\/\/ \u6587\u5b57\u5217\u304c\u7a7a\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif ($str === '') { \/* ... *\/ }\n\n\/\/ \u914d\u5217\u304c\u7a7a\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif (count($array) === 0) { \/* ... *\/ }\n\n\/\/ \u6570\u5024\u304c0\u304b\u3069\u3046\u304b\u306e\u30c1\u30a7\u30c3\u30af\nif ($num === 0) { \/* ... *\/ }\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-35\">2. \u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306b\u5fdc\u3058\u305f\u9069\u5207\u306a\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0<\/h4>\n\n\n\n<p>\u5358\u306b\u30a8\u30e9\u30fc\u3092\u51fa\u3059\u3060\u3051\u3067\u306a\u304f\u3001\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306b\u5fdc\u3058\u305f\u9069\u5207\u306a\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0\u3092\u884c\u3044\u307e\u3057\u3087\u3046\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=\"\">function getConfig(string $key)\n{\n    global $config;\n    \n    if (empty($config[$key])) {\n        \/\/ \u958b\u767a\u74b0\u5883\u3067\u306f\u8a73\u7d30\u60c5\u5831\u3092\n        if (ENVIRONMENT === 'development') {\n            throw new Exception(\"\u8a2d\u5b9a\u30ad\u30fc '{$key}' \u304c\u898b\u3064\u304b\u308a\u307e\u305b\u3093\");\n        }\n        \n        \/\/ \u672c\u756a\u74b0\u5883\u3067\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u4f7f\u7528\n        return null;\n    }\n    \n    return $config[$key];\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-36\">3. \u5165\u529b\u5024\u306e\u691c\u8a3c\u3068\u51e6\u7406\u306e\u5206\u96e2<\/h4>\n\n\n\n<p>\u5165\u529b\u5024\u306e\u691c\u8a3c\u3068\u5b9f\u969b\u306e\u51e6\u7406\u3092\u5206\u96e2\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u8cac\u4efb\u5206\u96e2\u3068\u518d\u5229\u7528\u6027\u304c\u5411\u4e0a\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=\"\">\/\/ Validation class\nclass Validator\n{\n    public function validateUserInput(array $input): array\n    {\n        $errors = [];\n        \n        if (empty($input['username'])) {\n            $errors['username'] = '\u30e6\u30fc\u30b6\u30fc\u540d\u306f\u5fc5\u9808\u3067\u3059';\n        }\n        \n        if (empty($input['email'])) {\n            $errors['email'] = '\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306f\u5fc5\u9808\u3067\u3059';\n        } elseif (!filter_var($input['email'], FILTER_VALIDATE_EMAIL)) {\n            $errors['email'] = '\u6709\u52b9\u306a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u5165\u529b\u3057\u3066\u304f\u3060\u3055\u3044';\n        }\n        \n        return $errors;\n    }\n}\n\n\/\/ User service\nclass UserService\n{\n    private $validator;\n    \n    public function __construct(Validator $validator)\n    {\n        $this-&gt;validator = $validator;\n    }\n    \n    public function registerUser(array $input): array\n    {\n        \/\/ \u691c\u8a3c\u3068\u51e6\u7406\u306e\u5206\u96e2\n        $errors = $this-&gt;validator-&gt;validateUserInput($input);\n        \n        if (!empty($errors)) {\n            return ['success' =&gt; false, 'errors' =&gt; $errors];\n        }\n        \n        \/\/ \u691c\u8a3c\u304c\u901a\u904e\u3057\u305f\u3089\u51e6\u7406\u3092\u5b9f\u884c\n        $userId = $this-&gt;createUser($input);\n        \n        return ['success' =&gt; true, 'user_id' =&gt; $userId];\n    }\n    \n    private function createUser(array $input): int\n    {\n        \/\/ \u30e6\u30fc\u30b6\u30fc\u4f5c\u6210\u51e6\u7406\n        return 123; \/\/ \u4eee\u306e\u30e6\u30fc\u30b6\u30fcID\n    }\n}\n<\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"i-37\">4. \u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u3084\u30e9\u30a4\u30d6\u30e9\u30ea\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306b\u5f93\u3046<\/h4>\n\n\n\n<p>\u5229\u7528\u3057\u3066\u3044\u308b\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u3084\u30e9\u30a4\u30d6\u30e9\u30ea\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306b\u5f93\u3046\u3053\u3068\u3067\u3001\u4e00\u8cab\u6027\u306e\u3042\u308b\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\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=\"\">\/\/ Laravel\u306e\u4f8b\npublic function store(Request $request)\n{\n    \/\/ Laravel\u306e\u5834\u5408\u3001empty()\u3088\u308a\u3082validate\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u7528\u304c\u63a8\u5968\u3055\u308c\u308b\n    $validated = $request-&gt;validate([\n        'title' =&gt; 'required|max:255',\n        'body' =&gt; 'required',\n        'published' =&gt; 'boolean',\n    ]);\n    \n    $post = Post::create($validated);\n    \n    return redirect()-&gt;route('posts.show', $post);\n}\n\n\/\/ Symfony\u306e\u4f8b\npublic function processForm(Request $request)\n{\n    $form = $this-&gt;createForm(UserType::class);\n    $form-&gt;handleRequest($request);\n    \n    if ($form-&gt;isSubmitted() &amp;&amp; $form-&gt;isValid()) {\n        $user = $form-&gt;getData();\n        $this-&gt;entityManager-&gt;persist($user);\n        $this-&gt;entityManager-&gt;flush();\n        \n        return $this-&gt;redirectToRoute('user_success');\n    }\n    \n    return $this-&gt;render('user\/form.html.twig', [\n        'form' =&gt; $form-&gt;createView(),\n    ]);\n}\n<\/pre>\n\n\n\n<p>\u4ee5\u4e0a\u306e7\u3064\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u610f\u8b58\u3059\u308b\u3053\u3068\u3067\u3001<code>empty()<\/code>\u95a2\u6570\u3092\u3088\u308a\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3057\u3001\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u6027\u3068\u5b89\u5168\u6027\u306e\u9ad8\u3044PHP\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Warning: Undefined array key &#8220;is_admin&#8221; in \/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/ &#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],"tags":[],"class_list":{"0":"post-3399","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-php","7":"nothumb"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3399","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=3399"}],"version-history":[{"count":1,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3399\/revisions"}],"predecessor-version":[{"id":3400,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/3399\/revisions\/3400"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3399"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3399"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3399"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}