<!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>Applies the callback to the elements of the given arrays</title>
</head>
<body><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="function.array-keys.html">array_keys</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.array-merge-recursive.html">array_merge_recursive</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-map" class="refentry">
<div class="refnamediv">
<h1 class="refname">array_map</h1>
<p class="verinfo">(PHP 4 >= 4.0.6, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">array_map</span> — <span class="dc-title">Applies the callback to the elements of the given arrays</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.array-map-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">array</span> <span class="methodname"><strong>array_map</strong></span>
( <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
, <span class="methodparam"><span class="type">array</span> <code class="parameter">$array1</code></span>
[, <span class="methodparam"><span class="type">array</span> <code class="parameter">$...</code></span>
] )</div>
<p class="para rdfs-comment">
<span class="function"><strong>array_map()</strong></span> returns an array containing all
the elements of <code class="parameter">array1</code> after applying the
<code class="parameter">callback</code> function to each one.
The number of parameters that the <code class="parameter">callback</code>
function accepts
should match the number of arrays
passed to the <span class="function"><strong>array_map()</strong></span>
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.array-map-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<code class="parameter">callback</code></dt>
<dd>
<p class="para">
Callback function to run for each element in each array.
</p>
</dd>
<dt>
<code class="parameter">array1</code></dt>
<dd>
<p class="para">
An array to run through the <code class="parameter">callback</code> function.
</p>
</dd>
<dt>
<code class="parameter">...</code></dt>
<dd>
<p class="para">
Variable list of array arguments to run through the
<code class="parameter">callback</code> function.
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.array-map-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns an array containing all the elements of <code class="parameter">array1</code>
after applying the <code class="parameter">callback</code> function to each one.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.array-map-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="function.array-fill.example.basic">
<p><strong>Example #1 <span class="function"><strong>array_map()</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">cube</span><span style="color: #007700">(</span><span style="color: #0000BB">$n</span><span style="color: #007700">)<br />{<br /> return(</span><span style="color: #0000BB">$n </span><span style="color: #007700">* </span><span style="color: #0000BB">$n </span><span style="color: #007700">* </span><span style="color: #0000BB">$n</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= </span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">"cube"</span><span style="color: #007700">, </span><span style="color: #0000BB">$a</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$b</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>
This makes <var class="varname"><var class="varname">$b</var></var> have:
</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-6172">
<p><strong>Example #2 <span class="function"><strong>array_map()</strong></span> using a lambda function (as of PHP 5.3.0)</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$func </span><span style="color: #007700">= function(</span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> return </span><span style="color: #0000BB">$value </span><span style="color: #007700">* </span><span style="color: #0000BB">2</span><span style="color: #007700">;<br />};<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #0000BB">$func</span><span style="color: #007700">, </span><span style="color: #0000BB">range</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">)));<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents screen">
<div class="cdata"><pre>
Array
(
[0] => 2
[1] => 4
[2] => 6
[3] => 8
[4] => 10
)
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-6173">
<p><strong>Example #3 <span class="function"><strong>array_map()</strong></span> - using more arrays</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">show_Spanish</span><span style="color: #007700">(</span><span style="color: #0000BB">$n</span><span style="color: #007700">, </span><span style="color: #0000BB">$m</span><span style="color: #007700">)<br />{<br /> return(</span><span style="color: #DD0000">"The number </span><span style="color: #0000BB">$n</span><span style="color: #DD0000"> is called </span><span style="color: #0000BB">$m</span><span style="color: #DD0000"> in Spanish"</span><span style="color: #007700">);<br />}<br /><br />function </span><span style="color: #0000BB">map_Spanish</span><span style="color: #007700">(</span><span style="color: #0000BB">$n</span><span style="color: #007700">, </span><span style="color: #0000BB">$m</span><span style="color: #007700">)<br />{<br /> return(array(</span><span style="color: #0000BB">$n </span><span style="color: #007700">=> </span><span style="color: #0000BB">$m</span><span style="color: #007700">));<br />}<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"uno"</span><span style="color: #007700">, </span><span style="color: #DD0000">"dos"</span><span style="color: #007700">, </span><span style="color: #DD0000">"tres"</span><span style="color: #007700">, </span><span style="color: #DD0000">"cuatro"</span><span style="color: #007700">, </span><span style="color: #DD0000">"cinco"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= </span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">"show_Spanish"</span><span style="color: #007700">, </span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$d </span><span style="color: #007700">= </span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">"map_Spanish"</span><span style="color: #007700">, </span><span style="color: #0000BB">$a </span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$d</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>
// printout of $c
Array
(
[0] => The number 1 is called uno in Spanish
[1] => The number 2 is called dos in Spanish
[2] => The number 3 is called tres in Spanish
[3] => The number 4 is called cuatro in Spanish
[4] => The number 5 is called cinco in Spanish
)
// printout of $d
Array
(
[0] => Array
(
[1] => uno
)
[1] => Array
(
[2] => dos
)
[2] => Array
(
[3] => tres
)
[3] => Array
(
[4] => cuatro
)
[4] => Array
(
[5] => cinco
)
)
</pre></div>
</div>
</div>
</p>
<p class="para">
Usually when using two or more arrays, they should be of equal length
because the callback function is applied in parallel to the corresponding
elements.
If the arrays are of unequal length, shorter ones will be extended with empty
elements to match the length of the longest.
</p>
<p class="para">
An interesting use of this function is to construct an array of arrays,
which can be easily performed by using <strong><code>NULL</code></strong>
as the name of the callback function
</p>
<p class="para">
<div class="example" id="example-6174">
<p><strong>Example #4 Creating an array of arrays</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"one"</span><span style="color: #007700">, </span><span style="color: #DD0000">"two"</span><span style="color: #007700">, </span><span style="color: #DD0000">"three"</span><span style="color: #007700">, </span><span style="color: #DD0000">"four"</span><span style="color: #007700">, </span><span style="color: #DD0000">"five"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"uno"</span><span style="color: #007700">, </span><span style="color: #DD0000">"dos"</span><span style="color: #007700">, </span><span style="color: #DD0000">"tres"</span><span style="color: #007700">, </span><span style="color: #DD0000">"cuatro"</span><span style="color: #007700">, </span><span style="color: #DD0000">"cinco"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$d </span><span style="color: #007700">= </span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">, </span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$d</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
Array
(
[0] => Array
(
[0] => 1
[1] => one
[2] => uno
)
[1] => Array
(
[0] => 2
[1] => two
[2] => dos
)
[2] => Array
(
[0] => 3
[1] => three
[2] => tres
)
[3] => Array
(
[0] => 4
[1] => four
[2] => cuatro
)
[4] => Array
(
[0] => 5
[1] => five
[2] => cinco
)
)
</pre></div>
</div>
</div>
</p>
<p class="para">
The returned array will preserve the keys of the array argument if and only
if exactly one array is passed. If more than one array is passed, the
returned array will have sequential integer keys.
</p>
<p class="para">
<div class="example" id="example-6175">
<p><strong>Example #5 <span class="function"><strong>array_map()</strong></span> - with string keys</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$arr </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"stringkey" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"value"</span><span style="color: #007700">);<br />function </span><span style="color: #0000BB">cb1</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">) {<br /> return array (</span><span style="color: #0000BB">$a</span><span style="color: #007700">);<br />}<br />function </span><span style="color: #0000BB">cb2</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">) {<br /> return array (</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">);<br />}<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">"cb1"</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">"cb2"</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</span><span style="color: #007700">, </span><span style="color: #0000BB">$arr</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(1) {
["stringkey"]=>
array(1) {
[0]=>
string(5) "value"
}
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
array(1) {
["stringkey"]=>
string(5) "value"
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.array-map-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><span class="function"><a href="function.array-filter.html" class="function" rel="rdfs-seeAlso">array_filter()</a> - Filters elements of an array using a callback function</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 supplied function to every member of an array</span></li>
<li class="member">information about the <a href="language.pseudo-types.html#language.types.callback" class="link">callback</a> type</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-keys.html">array_keys</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.array-merge-recursive.html">array_merge_recursive</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>
