{"id":1084,"date":"2021-04-13T01:04:06","date_gmt":"2021-04-13T01:04:06","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=1084"},"modified":"2025-04-06T03:42:00","modified_gmt":"2025-04-06T03:42:00","slug":"php-array_key_exists","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-array_key_exists\/","title":{"rendered":"PHP array_key_exists"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you will learn how to use the PHP <code>array_key_exists()<\/code> function to determine if a key exists in an array.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='introduction-to-the-php-array_key_exists-function'>Introduction to the PHP array_key_exists() function <a href=\"#introduction-to-the-php-array_key_exists-function\" class=\"anchor\" id=\"introduction-to-the-php-array_key_exists-function\" title=\"Anchor for Introduction to the PHP array_key_exists() function\">#<\/a><\/h2>\n\n\n\n<p>The PHP <code>array_key_exists()<\/code> function checks if a key exists in an <a href=\"https:\/\/phptutorial.net\/php-tutorial\/php-associative-arrays\/\">array<\/a>. <\/p>\n\n\n\n<p>Here&#8217;s the syntax of the <code>array_key_exists()<\/code> function:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"PHP\" data-shcb-language-slug=\"php\"><span><code class=\"hljs language-php\">array_key_exists ( string|int $key , <span class=\"hljs-keyword\">array<\/span> $array ) : bool<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PHP<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">php<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this syntax:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>$key<\/code> is the key to check.<\/li>\n\n\n\n<li><code>$array<\/code> is an array with keys to check.<\/li>\n<\/ul>\n\n\n\n<p>The <code>array_key_exists()<\/code> function returns <code>true<\/code> if the <code>$key<\/code> exists in the <code>$array<\/code>. Otherwise, it returns <code>false<\/code>.<\/p>\n\n\n\n<p>Note that the <code>array_key_exists()<\/code> function searches for the key in the first dimension of the <code>$array<\/code> only. If the <code>$array<\/code> is <a href=\"https:\/\/phptutorial.net\/php-tutorial\/php-multidimensional-array\/\">multidimensional<\/a>, the <code>array_key_exists()<\/code> function won&#8217;t find the <code>$key<\/code> in the nested dimension.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='php-array_key_exists-function-example'>PHP array_key_exists() function example <a href=\"#php-array_key_exists-function-example\" class=\"anchor\" id=\"php-array_key_exists-function-example\" title=\"Anchor for PHP array_key_exists() function example\">#<\/a><\/h2>\n\n\n\n<p>The following example uses the <code>array_key_exists()<\/code> function to check if the key <code>'admin'<\/code> exists in the <code>$roles<\/code> array:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\"><span class=\"php\"><span class=\"hljs-meta\">&lt;?php<\/span>\n\n$roles = &#91;\n\t<span class=\"hljs-string\">'admin'<\/span> =&gt; <span class=\"hljs-number\">1<\/span>,\n\t<span class=\"hljs-string\">'approver'<\/span> =&gt; <span class=\"hljs-number\">2<\/span>,\n\t<span class=\"hljs-string\">'editor'<\/span> =&gt; <span class=\"hljs-number\">3<\/span>,\n\t<span class=\"hljs-string\">'subscriber'<\/span> =&gt; <span class=\"hljs-number\">4<\/span>\n];\n\n$result = array_key_exists(<span class=\"hljs-string\">'admin'<\/span>, $roles);\n\nvar_dump($result); <span class=\"hljs-comment\">\/\/ bool(true)<\/span><\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/phptutorial.net\/playground\/?q=PD9waHAKCiRyb2xlcyA9IFsKCSdhZG1pbicgPT4gMSwKCSdhcHByb3ZlcicgPT4gMiwKCSdlZGl0b3InID0-IDMsCgknc3Vic2NyaWJlcicgPT4gNApdOwoKJHJlc3VsdCA9IGFycmF5X2tleV9leGlzdHMoJ2FkbWluJywgJHJvbGVzKTsKCnZhcl9kdW1wKCRyZXN1bHQpOyAvLyBib29sKHRydWUp\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\">bool(<span class=\"hljs-literal\">true<\/span>)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The following example returns <code>false<\/code> because the <code>$roles<\/code> array doesn&#8217;t have the key <code>publisher<\/code>:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\"><span class=\"php\"><span class=\"hljs-meta\">&lt;?php<\/span>\n\n$roles = &#91;\n\t<span class=\"hljs-string\">'admin'<\/span> =&gt; <span class=\"hljs-number\">1<\/span>,\n\t<span class=\"hljs-string\">'approver'<\/span> =&gt; <span class=\"hljs-number\">2<\/span>,\n\t<span class=\"hljs-string\">'editor'<\/span> =&gt; <span class=\"hljs-number\">3<\/span>,\n\t<span class=\"hljs-string\">'subscriber'<\/span> =&gt; <span class=\"hljs-number\">4<\/span>\n];\n\n$result = array_key_exists(<span class=\"hljs-string\">'publisher'<\/span>, $roles);\n\nvar_dump($result); <span class=\"hljs-comment\">\/\/ bool(false)<\/span><\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/phptutorial.net\/playground\/?q=PD9waHAKCiRyb2xlcyA9IFsKCSdhZG1pbicgPT4gMSwKCSdhcHByb3ZlcicgPT4gMiwKCSdlZGl0b3InID0-IDMsCgknc3Vic2NyaWJlcicgPT4gNApdOwoKJHJlc3VsdCA9IGFycmF5X2tleV9leGlzdHMoJ3B1Ymxpc2hlcicsICRyb2xlcyk7Cgp2YXJfZHVtcCgkcmVzdWx0KTsgLy8gYm9vbChmYWxzZSk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='php-array_key_exists-vs-isset'>PHP array_key_exists() vs isset() <a href=\"#php-array_key_exists-vs-isset\" class=\"anchor\" id=\"php-array_key_exists-vs-isset\" title=\"Anchor for PHP array_key_exists() vs isset()\">#<\/a><\/h2>\n\n\n\n<p>If the value of the array element is not <code>null<\/code>, both <code>array_key_exists()<\/code> and <code>isset()<\/code> return <code>true<\/code> if the key exists in an array and <code>false<\/code> if it doesn&#8217;t. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\"><span class=\"php\"><span class=\"hljs-meta\">&lt;?php<\/span>\n\n$roles = &#91;\n\t<span class=\"hljs-string\">'admin'<\/span> =&gt; <span class=\"hljs-number\">1<\/span>,\n\t<span class=\"hljs-string\">'approver'<\/span> =&gt; <span class=\"hljs-number\">2<\/span>,\n\t<span class=\"hljs-string\">'editor'<\/span> =&gt; <span class=\"hljs-number\">3<\/span>,\n\t<span class=\"hljs-string\">'subscriber'<\/span> =&gt; <span class=\"hljs-number\">4<\/span>\n];\n\nvar_dump(<span class=\"hljs-keyword\">isset<\/span>($roles&#91;<span class=\"hljs-string\">'approver'<\/span>]));  <span class=\"hljs-comment\">\/\/ bool(true)<\/span>\nvar_dump(array_key_exists(<span class=\"hljs-string\">'approver'<\/span>, $roles)); <span class=\"hljs-comment\">\/\/ bool(true)<\/span><\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/phptutorial.net\/playground\/?q=PD9waHAKCiRyb2xlcyA9IFsKCSdhZG1pbicgPT4gMSwKCSdhcHByb3ZlcicgPT4gMiwKCSdlZGl0b3InID0-IDMsCgknc3Vic2NyaWJlcicgPT4gNApdOwoKdmFyX2R1bXAoaXNzZXQoJHJvbGVzWydhcHByb3ZlciddKSk7ICAvLyBib29sKHRydWUpCnZhcl9kdW1wKGFycmF5X2tleV9leGlzdHMoJ2FwcHJvdmVyJywgJHJvbGVzKSk7IC8vIGJvb2wodHJ1ZSk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>The following example returns <code>false<\/code> because the <code>user<\/code> key doesn&#8217;t exist in the <code>$roles<\/code> array:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\"><span class=\"php\"><span class=\"hljs-meta\">&lt;?php<\/span>\n\n$roles = &#91;\n\t<span class=\"hljs-string\">'admin'<\/span> =&gt; <span class=\"hljs-number\">1<\/span>,\n\t<span class=\"hljs-string\">'approver'<\/span> =&gt; <span class=\"hljs-number\">2<\/span>,\n\t<span class=\"hljs-string\">'editor'<\/span> =&gt; <span class=\"hljs-number\">3<\/span>,\n\t<span class=\"hljs-string\">'subscriber'<\/span> =&gt; <span class=\"hljs-number\">4<\/span>\n];\n\nvar_dump(<span class=\"hljs-keyword\">isset<\/span>($roles&#91;<span class=\"hljs-string\">'user'<\/span>]));  <span class=\"hljs-comment\">\/\/ bool(false)<\/span>\nvar_dump(array_key_exists(<span class=\"hljs-string\">'user'<\/span>, $roles)); <span class=\"hljs-comment\">\/\/ bool(false)<\/span><\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/phptutorial.net\/playground\/?q=PD9waHAKCiRyb2xlcyA9IFsKCSdhZG1pbicgPT4gMSwKCSdhcHByb3ZlcicgPT4gMiwKCSdlZGl0b3InID0-IDMsCgknc3Vic2NyaWJlcicgPT4gNApdOwoKdmFyX2R1bXAoaXNzZXQoJHJvbGVzWyd1c2VyJ10pKTsgIC8vIGJvb2woZmFsc2UpCnZhcl9kdW1wKGFycmF5X2tleV9leGlzdHMoJ3VzZXInLCAkcm9sZXMpKTsgLy8gYm9vbChmYWxzZSk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>However, if the value of a key is <code>null<\/code>, the <code>isset()<\/code> will return <code>false<\/code> while the <code>array_key_exists()<\/code> function returns <code>true<\/code>. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\"><span class=\"php\"><span class=\"hljs-meta\">&lt;?php<\/span>\n\n$post = &#91;\n\t<span class=\"hljs-string\">'title'<\/span> =&gt; <span class=\"hljs-string\">'PHP array_key_exists'<\/span>,\n\t<span class=\"hljs-string\">'thumbnail'<\/span> =&gt; <span class=\"hljs-keyword\">null<\/span>\n];\n\nvar_dump(array_key_exists(<span class=\"hljs-string\">'thumbnail'<\/span>, $post)); <span class=\"hljs-comment\">\/\/ bool(true)<\/span>\nvar_dump(<span class=\"hljs-keyword\">isset<\/span>($post&#91;<span class=\"hljs-string\">'thumbnail'<\/span>])); <span class=\"hljs-comment\">\/\/ bool(false)<\/span><\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/phptutorial.net\/playground\/?q=PD9waHAKCiRwb3N0ID0gWwoJJ3RpdGxlJyA9PiAnUEhQIGFycmF5X2tleV9leGlzdHMnLAoJJ3RodW1ibmFpbCcgPT4gbnVsbApdOwoKdmFyX2R1bXAoYXJyYXlfa2V5X2V4aXN0cygndGh1bWJuYWlsJywgJHBvc3QpKTsgLy8gYm9vbCh0cnVlKQp2YXJfZHVtcChpc3NldCgkcG9zdFsndGh1bWJuYWlsJ10pKTsgLy8gYm9vbChmYWxzZSk\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='summary'>Summary <a href=\"#summary\" class=\"anchor\" id=\"summary\" title=\"Anchor for Summary\">#<\/a><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use the PHP <code>array_key_exists()<\/code> function to check if a key exists in an array.<\/li>\n<\/ul>\n<div class=\"helpful-block-content\" data-title=\"\">\n\t<header>\n\t\t<div class=\"wth-question\">Did you find this tutorial useful?<\/div>\n\t\t<div 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array.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":15,"menu_order":50,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1084","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/pages\/1084","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/comments?post=1084"}],"version-history":[{"count":4,"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/pages\/1084\/revisions"}],"predecessor-version":[{"id":3069,"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/pages\/1084\/revisions\/3069"}],"up":[{"embeddable":true,"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/pages\/15"}],"wp:attachment":[{"href":"https:\/\/www.phptutorial.net\/wp-json\/wp\/v2\/media?parent=1084"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}