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<title>Sort the entries with a user-defined comparison function and maintain key association</title>
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<h1 class="refname">ArrayObject::uasort</h1>
<p class="verinfo">(PHP 5 >= 5.2.0)</p><p class="refpurpose"><span class="refname">ArrayObject::uasort</span> — <span class="dc-title">Sort the entries with a user-defined comparison function and maintain key association</span></p>
</div>
<div class="refsect1 description" id="refsect1-arrayobject.uasort-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>ArrayObject::uasort</strong></span>
( <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$cmp_function</code></span>
)</div>
<p class="para rdfs-comment">
This function sorts the entries such that keys maintain their
correlation with the entry that they are associated with, using a
user-defined comparison function.
</p>
<p class="para">
This is used mainly when sorting associative arrays where the actual
element order is significant.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-arrayobject.uasort-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">cmp_function</code></em></span>
<dd>
<p class="para">
Function <em><code class="parameter">cmp_function</code></em> should accept two
parameters which will be filled by pairs of entries.
The comparison function must return an integer less than, equal
to, or greater than zero if the first argument is considered to
be respectively less than, equal to, or greater than the
second.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-arrayobject.uasort-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
No value is returned.
</p>
</div>
<div class="refsect1 examples" id="refsect1-arrayobject.uasort-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3996">
<p><strong>Example #1 <span class="function"><strong>ArrayObject::uasort()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Comparison function<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">cmp</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">) {<br /> if (</span><span style="color: #0000BB">$a </span><span style="color: #007700">== </span><span style="color: #0000BB">$b</span><span style="color: #007700">) {<br /> return </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /> }<br /> return (</span><span style="color: #0000BB">$a </span><span style="color: #007700">< </span><span style="color: #0000BB">$b</span><span style="color: #007700">) ? -</span><span style="color: #0000BB">1 </span><span style="color: #007700">: </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// Array to be sorted<br /></span><span style="color: #0000BB">$array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'a' </span><span style="color: #007700">=> </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #DD0000">'b' </span><span style="color: #007700">=> </span><span style="color: #0000BB">8</span><span style="color: #007700">, </span><span style="color: #DD0000">'c' </span><span style="color: #007700">=> -</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'d' </span><span style="color: #007700">=> -</span><span style="color: #0000BB">9</span><span style="color: #007700">, </span><span style="color: #DD0000">'e' </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">'f' </span><span style="color: #007700">=> </span><span style="color: #0000BB">5</span><span style="color: #007700">, </span><span style="color: #DD0000">'g' </span><span style="color: #007700">=> </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #DD0000">'h' </span><span style="color: #007700">=> -</span><span style="color: #0000BB">4</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$arrayObject </span><span style="color: #007700">= new </span><span style="color: #0000BB">ArrayObject</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arrayObject</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Sort and print the resulting array<br /></span><span style="color: #0000BB">$arrayObject</span><span style="color: #007700">-></span><span style="color: #0000BB">uasort</span><span style="color: #007700">(</span><span style="color: #DD0000">'cmp'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$arrayObject</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
(
[a] => 4
[b] => 8
[c] => -1
[d] => -9
[e] => 2
[f] => 5
[g] => 3
[h] => -4
)
Array
(
[d] => -9
[h] => -4
[c] => -1
[e] => 2
[g] => 3
[a] => 4
[f] => 5
[b] => 8
)
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-arrayobject.uasort-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="methodname"><a href="arrayobject.asort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::asort()</a> - Sort the entries by value</span></li>
<li class="member"> <span class="methodname"><a href="arrayobject.ksort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::ksort()</a> - Sort the entries by key</span></li>
<li class="member"> <span class="methodname"><a href="arrayobject.natsort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::natsort()</a> - Sort entries using a "natural order" algorithm</span></li>
<li class="member"> <span class="methodname"><a href="arrayobject.natcasesort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::natcasesort()</a> - Sort an array using a case insensitive "natural order" algorithm</span></li>
<li class="member"> <span class="methodname"><a href="arrayobject.uksort.html" class="methodname" rel="rdfs-seeAlso">ArrayObject::uksort()</a> - Sort the entries by keys using a user-defined comparison function</span></li>
</ul>
</p>
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