📄 function.array-key-exists.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Checks if the given key or index exists in the array</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-intersect.html">array_intersect</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-keys.html">array_keys</a></div> <div class="up"><a href="ref.array.html">Array Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.array-key-exists" class="refentry"> <div class="refnamediv"> <h1 class="refname">array_key_exists</h1> <p class="verinfo">(PHP 4 >= 4.0.7, PHP 5)</p><p class="refpurpose"><span class="refname">array_key_exists</span> — <span class="dc-title">Checks if the given key or index exists in the array</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><b><b>array_key_exists</b></b></span> ( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <tt class="parameter">$key</tt></span> , <span class="methodparam"><span class="type">array</span> <tt class="parameter">$search</tt></span> )</div> <p class="para rdfs-comment"> <b>array_key_exists()</b> returns <b><tt>TRUE</tt></b> if the given <i><tt class="parameter">key</tt></i> is set in the array. <i><tt class="parameter">key</tt></i> can be any value possible for an array index. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">key</tt></i></span> <dd> <p class="para"> Value to check. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">search</tt></i></span> <dd> <p class="para"> An array with keys to check. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <b><tt>TRUE</tt></b> on success or <b><tt>FALSE</tt></b> on failure. </p> </div> <div class="refsect1 changelog"> <h3 class="title">ChangeLog</h3> <p class="para"> <table class="informaltable"> <colgroup> <thead valign="middle"> <tr valign="middle"> <th colspan="1">Version</th> <th colspan="1">Description</th> </tr> </thead> <tbody valign="middle" class="tbody"> <tr valign="middle"> <td colspan="1" rowspan="1" align="left">5.3.0</td> <td colspan="1" rowspan="1" align="left"> This function doesn't work with objetcs anymore, <a href="function.property-exists.html" class="function">property_exists()</a> should be used in this case. </td> </tr> </tbody> </colgroup> </table> </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>array_key_exists()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$search_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'first' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'second' </span><span style="color: #007700">=> </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br />if (</span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'first'</span><span style="color: #007700">, </span><span style="color: #0000BB">$search_array</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"The 'first' element is in the array"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> <blockquote><p><b class="note">Note</b>: <span class="simpara"> The name of this function is <b>key_exists()</b> in PHP 4.0.6. </span> </p></blockquote> <div class="example"> <p><b>Example #2 <b>array_key_exists()</b> vs <a href="function.isset.html" class="function">isset()</a></b></p> <div class="example-contents"><p> <a href="function.isset.html" class="function">isset()</a> does not return <b><tt>TRUE</tt></b> for array keys that correspond to a <b><tt>NULL</tt></b> value, while <b>array_key_exists()</b> does. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$search_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'first' </span><span style="color: #007700">=> </span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #DD0000">'second' </span><span style="color: #007700">=> </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// returns false<br /></span><span style="color: #007700">isset(</span><span style="color: #0000BB">$search_array</span><span style="color: #007700">[</span><span style="color: #DD0000">'first'</span><span style="color: #007700">]);<br /><br /></span><span style="color: #FF8000">// returns true<br /></span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'first'</span><span style="color: #007700">, </span><span style="color: #0000BB">$search_array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.isset.html" class="function" rel="rdfs-seeAlso">isset()</a></li> <li class="member"><a href="function.array-keys.html" class="function" rel="rdfs-seeAlso">array_keys()</a></li> <li class="member"><a href="function.in-array.html" class="function" rel="rdfs-seeAlso">in_array()</a></li> <li class="member"><a href="function.property-exists.html" class="function" rel="rdfs-seeAlso">property_exists()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-intersect.html">array_intersect</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-keys.html">array_keys</a></div> <div class="up"><a href="ref.array.html">Array Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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