function.array-keys.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>Return all the keys of an 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-key-exists.html">array_key_exists</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-map.html">array_map</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-keys" class="refentry"> <div class="refnamediv"> <h1 class="refname">array_keys</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">array_keys</span> — <span class="dc-title">Return all the keys of an array</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">array</span> <span class="methodname"><b><b>array_keys</b></b></span> ( <span class="methodparam"><span class="type">array</span> <tt class="parameter">$input</tt></span> [, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <tt class="parameter">$search_value</tt></span> [, <span class="methodparam"><span class="type">bool</span> <tt class="parameter">$strict</tt></span> ]] )</div> <p class="para rdfs-comment"> <b>array_keys()</b> returns the keys, numeric and string, from the <i><tt class="parameter">input</tt></i> array. </p> <p class="para"> If the optional <i><tt class="parameter">search_value</tt></i> is specified, then only the keys for that value are returned. Otherwise, all the keys from the <i><tt class="parameter">input</tt></i> are returned. As of PHP 5, you can use <i><tt class="parameter">strict</tt></i> parameter for comparison including type (===). </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">input</tt></i></span> <dd> <p class="para"> An array containing keys to return. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">search_value</tt></i></span> <dd> <p class="para"> If specified, then only keys containing these values are returned. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">strict</tt></i></span> <dd> <p class="para"> As of PHP 5, this parameter determines if strict comparision (===) should be used during the search. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns an array of all the keys in <i><tt class="parameter">input</tt></i>. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>array_keys()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= array(</span><span style="color: #0000BB">0 </span><span style="color: #007700">=> </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #DD0000">"color" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"red"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_keys</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"blue"</span><span style="color: #007700">, </span><span style="color: #DD0000">"red"</span><span style="color: #007700">, </span><span style="color: #DD0000">"green"</span><span style="color: #007700">, </span><span style="color: #DD0000">"blue"</span><span style="color: #007700">, </span><span style="color: #DD0000">"blue"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_keys</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">, </span><span style="color: #DD0000">"blue"</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"color" </span><span style="color: #007700">=> array(</span><span style="color: #DD0000">"blue"</span><span style="color: #007700">, </span><span style="color: #DD0000">"red"</span><span style="color: #007700">, </span><span style="color: #DD0000">"green"</span><span style="color: #007700">),<br /> </span><span style="color: #DD0000">"size" </span><span style="color: #007700">=> array(</span><span style="color: #DD0000">"small"</span><span style="color: #007700">, </span><span style="color: #DD0000">"medium"</span><span style="color: #007700">, </span><span style="color: #DD0000">"large"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_keys</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</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"><pre><div class="cdata"><pre>Array( [0] => 0 [1] => color)Array( [0] => 0 [1] => 3 [2] => 4)Array( [0] => color [1] => size)</pre></div> </pre></div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.array-values.html" class="function" rel="rdfs-seeAlso">array_values()</a></li> <li class="member"><a href="function.array-key-exists.html" class="function" rel="rdfs-seeAlso">array_key_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-key-exists.html">array_key_exists</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-map.html">array_map</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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