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<title>Sort multiple or multi-dimensional arrays</title>
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<div class="refnamediv">
<h1 class="refname">array_multisort</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">array_multisort</span> — <span class="dc-title">Sort multiple or multi-dimensional arrays</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.array-multisort-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>array_multisort</strong></span>
( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array1</code></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$array1_sort_order</code><span class="initializer"> = SORT_ASC</span></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$array1_sort_flags</code><span class="initializer"> = SORT_REGULAR</span></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$...</code></span>
]]] )</div>
<p class="para rdfs-comment">
<span class="function"><strong>array_multisort()</strong></span> can be used to sort several
arrays at once, or a multi-dimensional array by one or more
dimensions.
</p>
<p class="para">
Associative (<span class="type"><a href="language.types.string.html" class="type string">string</a></span>) keys will be maintained, but numeric
keys will be re-indexed.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.array-multisort-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">array1</code></em></span>
<dd>
<p class="para">
An <span class="type"><a href="language.types.array.html" class="type array">array</a></span> being sorted.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">array1_sort_order</code></em></span>
<dd>
<p class="para">
The order used to sort the previous <span class="type"><a href="language.types.array.html" class="type array">array</a></span> argument. Either
<strong><code>SORT_ASC</code></strong> to sort ascendingly or <strong><code>SORT_DESC</code></strong>
to sort descendingly.
</p>
<p class="para">
This argument can be swapped with <em><code class="parameter">array1_sort_flags</code></em>
or omitted entirely, in which case <strong><code>SORT_ASC</code></strong> is assumed.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">array1_sort_flags</code></em></span>
<dd>
<p class="para">
Sort options for the previous <span class="type"><a href="language.types.array.html" class="type array">array</a></span> argument:
</p>
<p class="para">
Sorting type flags:
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara"><strong><code>SORT_REGULAR</code></strong> - compare items normally
(don't change types)</span>
</li>
<li class="listitem">
<span class="simpara"><strong><code>SORT_NUMERIC</code></strong> - compare items numerically</span>
</li>
<li class="listitem">
<span class="simpara"><strong><code>SORT_STRING</code></strong> - compare items as strings</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>SORT_LOCALE_STRING</code></strong> - compare items as
strings, based on the current locale. It uses the locale,
which can be changed using <span class="function"><a href="function.setlocale.html" class="function">setlocale()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>SORT_NATURAL</code></strong> - compare items as strings
using "natural ordering" like <span class="function"><a href="function.natsort.html" class="function">natsort()</a></span>
</span>
</li>
<li class="listitem">
<span class="simpara">
<strong><code>SORT_FLAG_CASE</code></strong> - can be combined
(bitwise OR) with
<strong><code>SORT_STRING</code></strong> or
<strong><code>SORT_NATURAL</code></strong> to sort strings case-insensitively
</span>
</li>
</ul>
</p>
<p class="para">
This argument can be swapped with <em><code class="parameter">array1_sort_order</code></em>
or omitted entirely, in which case <strong><code>SORT_REGULAR</code></strong> is assumed.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">...</code></em></span>
<dd>
<p class="para">
More arrays, optionally followed by sort order and flags.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.array-multisort-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.array-multisort-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>5.4.0</td>
<td>
The <strong><code>SORT_NATURAL</code></strong> and <strong><code>SORT_FLAG_CASE</code></strong>
were added to <em><code class="parameter">array1_sort_flags</code></em> as possible sort flags.
</td>
</tr>
<tr>
<td>5.3.0</td>
<td>
The <strong><code>SORT_LOCALE_STRING</code></strong> was added to
<em><code class="parameter">array1_sort_flags</code></em> as possible sort flags.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.array-multisort-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-4966">
<p><strong>Example #1 Sorting multiple arrays</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$ar1 </span><span style="color: #007700">= array(</span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$ar2 </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">array_multisort</span><span style="color: #007700">(</span><span style="color: #0000BB">$ar1</span><span style="color: #007700">, </span><span style="color: #0000BB">$ar2</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$ar1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$ar2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>
In this example, after sorting, the first array will contain 0,
10, 100, 100. The second array will contain 4, 1, 2, 3. The
entries in the second array corresponding to the identical
entries in the first array (100 and 100) were sorted as well.
</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
array(4) {
[0]=> int(0)
[1]=> int(10)
[2]=> int(100)
[3]=> int(100)
}
array(4) {
[0]=> int(4)
[1]=> int(1)
[2]=> int(2)
[3]=> int(3)
}
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-4967">
<p><strong>Example #2 Sorting multi-dimensional array</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$ar </span><span style="color: #007700">= array(<br /> array(</span><span style="color: #DD0000">"10"</span><span style="color: #007700">, </span><span style="color: #0000BB">11</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #DD0000">"a"</span><span style="color: #007700">),<br /> array( </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">"2"</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">)<br /> );<br /></span><span style="color: #0000BB">array_multisort</span><span style="color: #007700">(</span><span style="color: #0000BB">$ar</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">], </span><span style="color: #0000BB">SORT_ASC</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_STRING</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">$ar</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">], </span><span style="color: #0000BB">SORT_NUMERIC</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_DESC</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$ar</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>
In this example, after sorting, the first array will transform to
"10", 100, 100, 11, "a" (it was sorted as strings in ascending
order). The second will contain 1, 3, "2", 2, 1 (sorted as numbers,
in descending order).
</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
array(2) {
[0]=> array(5) {
[0]=> string(2) "10"
[1]=> int(100)
[2]=> int(100)
[3]=> int(11)
[4]=> string(1) "a"
}
[1]=> array(5) {
[0]=> int(1)
[1]=> int(3)
[2]=> string(1) "2"
[3]=> int(2)
[4]=> int(1)
}
}
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-4968">
<p><strong>Example #3 Sorting database results</strong></p>
<div class="example-contents"><p>
For this example, each element in the <var class="varname"><var class="varname">data</var></var>
array represents one row in a table. This type of dataset is typical
of database records.
</p></div>
<div class="example-contents"><p>
Example data:
</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
volume | edition
-------+--------
67 | 2
86 | 1
85 | 6
98 | 2
86 | 6
67 | 7
</pre></div>
</div>
<div class="example-contents"><p>
The data as an array, called <var class="varname"><var class="varname">data</var></var>. This would usually,
for example, be obtained by looping with <span class="function"><a href="function.mysql-fetch-assoc.html" class="function">mysql_fetch_assoc()</a></span>.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">67</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">86</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">85</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">6</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">98</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">86</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">6</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$data</span><span style="color: #007700">[] = array(</span><span style="color: #DD0000">'volume' </span><span style="color: #007700">=> </span><span style="color: #0000BB">67</span><span style="color: #007700">, </span><span style="color: #DD0000">'edition' </span><span style="color: #007700">=> </span><span style="color: #0000BB">7</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>
In this example, we will order by <var class="varname"><var class="varname">volume</var></var> descending,
<var class="varname"><var class="varname">edition</var></var> ascending.
</p></div>
<div class="example-contents"><p>
We have an array of rows, but <span class="function"><strong>array_multisort()</strong></span>
requires an array of columns, so we use the below code to obtain the
columns, then perform the sorting.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Obtain a list of columns<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$data </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$row</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$volume</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">] = </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #DD0000">'volume'</span><span style="color: #007700">];<br /> </span><span style="color: #0000BB">$edition</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">] = </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #DD0000">'edition'</span><span style="color: #007700">];<br />}<br /><br /></span><span style="color: #FF8000">// Sort the data with volume descending, edition ascending<br />// Add $data as the last parameter, to sort by the common key<br /></span><span style="color: #0000BB">array_multisort</span><span style="color: #007700">(</span><span style="color: #0000BB">$volume</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_DESC</span><span style="color: #007700">, </span><span style="color: #0000BB">$edition</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_ASC</span><span style="color: #007700">, </span><span style="color: #0000BB">$data</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>
The dataset is now sorted, and will look like this:
</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
volume | edition
-------+--------
98 | 2
86 | 1
86 | 6
85 | 6
67 | 2
67 | 7
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-4969">
<p><strong>Example #4 Case insensitive sorting</strong></p>
<div class="example-contents"><p>
Both <strong><code>SORT_STRING</code></strong> and
<strong><code>SORT_REGULAR</code></strong> are case sensitive, strings
starting with a capital letter will come before strings starting
with a lowercase letter.
</p></div>
<div class="example-contents"><p>
To perform a case insensitive search, force the sorting order to be
determined by a lowercase copy of the original array.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'Alpha'</span><span style="color: #007700">, </span><span style="color: #DD0000">'atomic'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Beta'</span><span style="color: #007700">, </span><span style="color: #DD0000">'bank'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$array_lowercase </span><span style="color: #007700">= </span><span style="color: #0000BB">array_map</span><span style="color: #007700">(</span><span style="color: #DD0000">'strtolower'</span><span style="color: #007700">, </span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">array_multisort</span><span style="color: #007700">(</span><span style="color: #0000BB">$array_lowercase</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_ASC</span><span style="color: #007700">, </span><span style="color: #0000BB">SORT_STRING</span><span style="color: #007700">, </span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</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] => Alpha
[1] => atomic
[2] => bank
[3] => Beta
)
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.array-multisort-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.usort.html" class="function" rel="rdfs-seeAlso">usort()</a> - Sort an array by values using a user-defined comparison function</span></li>
<li class="member">The <a href="array.sorting.html" class="link">comparison of array sorting functions</a></li>
</ul>
</p>
</div>
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