<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Gets the first key of an array</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-key-exists.html">array_key_exists</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-key-last.html">array_key_last</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-first" class="refentry"> <div class="refnamediv"> <h1 class="refname">array_key_first</h1> <p class="verinfo">(PHP 7 >= 7.3.0)</p><p class="refpurpose"><span class="refname">array_key_first</span> — <span class="dc-title">Gets the first key of an array</span></p> </div> <div class="refsect1 description" id="refsect1-function.array-key-first-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <span class="methodname"><strong>array_key_first</strong></span> ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span> )</div> <p class="para rdfs-comment"> Get the first key of the given <code class="parameter">array</code> without affecting the internal array pointer. </p> </div> <div class="refsect1 parameters" id="refsect1-function.array-key-first-parameters"> <h3 class="title">Parameters</h3> <dl> <dt> <code class="parameter">array</code></dt> <dd> <p class="para"> An array. </p> </dd> </dl> </div> <div class="refsect1 returnvalues" id="refsect1-function.array-key-first-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the first key of <code class="parameter">array</code> if the array is not empty; <strong><code>NULL</code></strong> otherwise. </p> </div> <div class="refsect1 examples" id="refsect1-function.array-key-first-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-6169"> <p><strong>Example #1 Basic <span class="function"><strong>array_key_first()</strong></span> Usage</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= [</span><span style="color: #DD0000">'a' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'b' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">'c' </span><span style="color: #007700">=> </span><span style="color: #0000BB">3</span><span style="color: #007700">];<br /><br /></span><span style="color: #0000BB">$firstKey </span><span style="color: #007700">= </span><span style="color: #0000BB">array_key_first</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">firstKey</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents screen"> <div class="cdata"><pre> string(1) "a" </pre></div> </div> </div> </p> </div> <div class="refsect1 seealso" id="refsect1-function.array-key-first-seealso"> <h3 class="title">See Also</h3> <ul class="simplelist"> <li class="member"><span class="function"><a href="function.array-key-last.html" class="function" rel="rdfs-seeAlso">array_key_last()</a> - Gets the last key of an array</span></li> <li class="member"><span class="function"><a href="function.reset.html" class="function" rel="rdfs-seeAlso">reset()</a> - Set the internal pointer of an array to its first element</span></li> </ul> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-key-exists.html">array_key_exists</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-key-last.html">array_key_last</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>