<!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>Filters elements of an array using a callback function</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.array-fill.html">array_fill</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-flip.html">array_flip</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-filter" class="refentry"> <div class="refnamediv"> <h1 class="refname">array_filter</h1> <p class="verinfo">(PHP 4 >= 4.0.6, PHP 5)</p><p class="refpurpose"><span class="refname">array_filter</span> — <span class="dc-title">Filters elements of an array using a callback function</span></p> </div> <div class="refsect1 description" id="refsect1-function.array-filter-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">array</span> <span class="methodname"><strong>array_filter</strong></span> ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span> [, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span> ] )</div> <p class="para rdfs-comment"> Iterates over each value in the <em><code class="parameter">array</code></em> passing them to the <em><code class="parameter">callback</code></em> function. If the <em><code class="parameter">callback</code></em> function returns true, the current value from <em><code class="parameter">array</code></em> is returned into the result array. Array keys are preserved. </p> </div> <div class="refsect1 parameters" id="refsect1-function.array-filter-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"> The array to iterate over </p> </dd> </dt> <dt> <span class="term"><em><code class="parameter">callback</code></em></span> <dd> <p class="para"> The callback function to use </p> <p class="para"> If no <em><code class="parameter">callback</code></em> is supplied, all entries of <em><code class="parameter">array</code></em> equal to <strong><code>FALSE</code></strong> (see <a href="language.types.boolean.html#language.types.boolean.casting" class="link">converting to boolean</a>) will be removed. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.array-filter-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the filtered array. </p> </div> <div class="refsect1 examples" id="refsect1-function.array-filter-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-4945"> <p><strong>Example #1 <span class="function"><strong>array_filter()</strong></span> example</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">odd</span><span style="color: #007700">(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #FF8000">// returns whether the input integer is odd<br /> </span><span style="color: #007700">return(</span><span style="color: #0000BB">$var </span><span style="color: #007700">& </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br />}<br /><br />function </span><span style="color: #0000BB">even</span><span style="color: #007700">(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #FF8000">// returns whether the input integer is even<br /> </span><span style="color: #007700">return(!(</span><span style="color: #0000BB">$var </span><span style="color: #007700">& </span><span style="color: #0000BB">1</span><span style="color: #007700">));<br />}<br /><br /></span><span style="color: #0000BB">$array1 </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"a"</span><span style="color: #007700">=></span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">"b"</span><span style="color: #007700">=></span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">"c"</span><span style="color: #007700">=></span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #DD0000">"d"</span><span style="color: #007700">=></span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #DD0000">"e"</span><span style="color: #007700">=></span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$array2 </span><span style="color: #007700">= array(</span><span style="color: #0000BB">6</span><span style="color: #007700">, </span><span style="color: #0000BB">7</span><span style="color: #007700">, </span><span style="color: #0000BB">8</span><span style="color: #007700">, </span><span style="color: #0000BB">9</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">11</span><span style="color: #007700">, </span><span style="color: #0000BB">12</span><span style="color: #007700">);<br /><br />echo </span><span style="color: #DD0000">"Odd :\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$array1</span><span style="color: #007700">, </span><span style="color: #DD0000">"odd"</span><span style="color: #007700">));<br />echo </span><span style="color: #DD0000">"Even:\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$array2</span><span style="color: #007700">, </span><span style="color: #DD0000">"even"</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> Odd : Array ( [a] => 1 [c] => 3 [e] => 5 ) Even: Array ( [0] => 6 [2] => 8 [4] => 10 [6] => 12 ) </pre></div> </div> </div> <div class="example" id="example-4946"> <p><strong>Example #2 <span class="function"><strong>array_filter()</strong></span> without <em><code class="parameter">callback</code></em></strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br />$entry </span><span style="color: #007700">= array(<br /> </span><span style="color: #0000BB">0 </span><span style="color: #007700">=> </span><span style="color: #DD0000">'foo'</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">1 </span><span style="color: #007700">=> </span><span style="color: #0000BB">false</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">2 </span><span style="color: #007700">=> -</span><span style="color: #0000BB">1</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">3 </span><span style="color: #007700">=> </span><span style="color: #0000BB">null</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">4 </span><span style="color: #007700">=> </span><span style="color: #DD0000">''<br /> </span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$entry</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> Array ( [0] => foo [2] => -1 ) </pre></div> </div> </div> </p> </div> <div class="refsect1 notes" id="refsect1-function.array-filter-notes"> <h3 class="title">Notes</h3> <div class="caution"><strong class="caution">Caution</strong> <p class="para"> If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined. </p> </div> </div> <div class="refsect1 seealso" id="refsect1-function.array-filter-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"> <span class="function"><a href="function.array-map.html" class="function" rel="rdfs-seeAlso">array_map()</a> - Applies the callback to the elements of the given arrays</span></li> <li class="member"> <span class="function"><a href="function.array-reduce.html" class="function" rel="rdfs-seeAlso">array_reduce()</a> - Iteratively reduce the array to a single value using a callback function</span></li> <li class="member"> <span class="function"><a href="function.array-walk.html" class="function" rel="rdfs-seeAlso">array_walk()</a> - Apply a user function to every member of an array</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-fill.html">array_fill</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.array-flip.html">array_flip</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>