<!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>Exchanges all keys with their associated values in 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-filter.html">array_filter</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-intersect-assoc.html">array_intersect_assoc</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-flip" class="refentry"> <div class="refnamediv"> <h1 class="refname">array_flip</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">array_flip</span> — <span class="dc-title">Exchanges all keys with their associated values in an array</span></p> </div> <div class="refsect1 description" id="refsect1-function.array-flip-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">array</span> <span class="methodname"><strong>array_flip</strong></span> ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span> )</div> <p class="para rdfs-comment"> <span class="function"><strong>array_flip()</strong></span> returns an <span class="type"><a href="language.types.array.html" class="type array">array</a></span> in flip order, i.e. keys from <em><code class="parameter">array</code></em> become values and values from <em><code class="parameter">array</code></em> become keys. </p> <p class="para"> Note that the values of <em><code class="parameter">array</code></em> need to be valid keys, i.e. they need to be either <span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> or <span class="type"><a href="language.types.string.html" class="type string">string</a></span>. A warning will be emitted if a value has the wrong type, and the key/value pair in question <em class="emphasis">will not be included in the result</em>. </p> <p class="para"> If a value has several occurrences, the latest key will be used as its value, and all others will be lost. </p> </div> <div class="refsect1 parameters" id="refsect1-function.array-flip-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><em><code class="parameter">array</code></em></span> <dd> <p class="para"> An array of key/value pairs to be flipped. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.array-flip-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the flipped array on success and <strong><code>NULL</code></strong> on failure. </p> </div> <div class="refsect1 examples" id="refsect1-function.array-flip-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-4947"> <p><strong>Example #1 <span class="function"><strong>array_flip()</strong></span> example</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$trans </span><span style="color: #007700">= </span><span style="color: #0000BB">array_flip</span><span style="color: #007700">(</span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$original </span><span style="color: #007700">= </span><span style="color: #0000BB">strtr</span><span style="color: #007700">(</span><span style="color: #0000BB">$str</span><span style="color: #007700">, </span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> </div> </p> <p class="para"> <div class="example" id="example-4948"> <p><strong>Example #2 <span class="function"><strong>array_flip()</strong></span> example : collision</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$trans </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"a" </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">"b" </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">"c" </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$trans </span><span style="color: #007700">= </span><span style="color: #0000BB">array_flip</span><span style="color: #007700">(</span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$trans</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p> now <var class="varname"><var class="varname">$trans</var></var> is: </p></div> <div class="example-contents screen"> <div class="cdata"><pre> Array ( [1] => b [2] => c ) </pre></div> </div> </div> </p> </div> <div class="refsect1 seealso" id="refsect1-function.array-flip-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"> <span class="function"><a href="function.array-values.html" class="function" rel="rdfs-seeAlso">array_values()</a> - Return all the values of an array</span></li> <li class="member"> <span class="function"><a href="function.array-keys.html" class="function" rel="rdfs-seeAlso">array_keys()</a> - Return all the keys or a subset of the keys of an array</span></li> <li class="member"> <span class="function"><a href="function.array-reverse.html" class="function" rel="rdfs-seeAlso">array_reverse()</a> - Return an array with elements in reverse order</span></li> </ul> </p> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-filter.html">array_filter</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-intersect-assoc.html">array_intersect_assoc</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>