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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>使用用户自定义的比较函数对数组中的值进行排序</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.usort" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">usort</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">usort</span> — <span class="dc-title">
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使用用户自定义的比较函数对数组中的值进行排序
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</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.usort-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>usort</strong></span>
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( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array</code></span>
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, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$value_compare_func</code></span>
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) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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本函数将用用户自定义的比较函数对一个数组中的值进行排序。
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如果要排序的数组需要用一种不寻常的标准进行排序，那么应该使用此函数。
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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If two members compare as equal, their relative order in the sorted array is undefined.
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</p>
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</p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数为 <code class="parameter">array</code>
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中的元素赋与新的键名。这将删除原有的键名，而不是仅仅将键名重新排序。</span></p></blockquote>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.usort-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">array</code></dt>
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<dd>
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<p class="para">
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输入的数组
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</p>
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</dd>
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<dt>
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<code class="parameter">cmp_function</code></dt>
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<dd>
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<p class="para">
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在第一个参数小于，等于或大于第二个参数时，该比较函数必须相应地返回一个小于，等于或大于 0 的整数。
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</p>
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<div class="methodsynopsis dc-description"><span class="methodname"><span class="replaceable">callback</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">$a</code></span>, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$b</code></span> ) : <span class="type">int</span></div>
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<div class="caution"><strong class="caution">Caution</strong>
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<p class="para">
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Returning <em class="emphasis">non-integer</em> values from the comparison
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function, such as <span class="type"><a href="language.types.float.html" class="type float">float</a></span>, will result in an internal cast to
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<span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> of the callback's return value. So values such as
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0.99 and 0.1 will both be cast to an integer value of 0, which will
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compare such values as equal.
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</p>
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</div>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.usort-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.usort-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-6122">
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<p><strong>Example #1 <span class="function"><strong>usort()</strong></span> 例子</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<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 />{<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: #0000BB">$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">, </span><span style="color: #0000BB">6</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #DD0000">"cmp"</span><span style="color: #007700">);<br /><br />foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$key</span><span style="color: #DD0000">: </span><span style="color: #0000BB">$value</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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0: 1
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1: 2
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2: 3
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3: 5
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4: 6
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</pre></div>
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</div>
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</div>
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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很明显在这个小例子中用 <span class="function"><a href="sort.html" class="function">sort()</a></span> 函数更合适。
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</p>
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</p></blockquote>
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<p class="para">
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<div class="example" id="example-6123">
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<p><strong>Example #2
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使用多维数组的 <span class="function"><strong>usort()</strong></span> 例子
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</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<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">$b</span><span style="color: #007700">)<br />{<br /> return </span><span style="color: #0000BB">strcmp</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">], </span><span style="color: #0000BB">$b</span><span style="color: #007700">[</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">]);<br />}<br /><br /></span><span style="color: #0000BB">$fruits</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">][</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">] = </span><span style="color: #DD0000">"lemons"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$fruits</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">][</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">] = </span><span style="color: #DD0000">"apples"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$fruits</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">][</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">] = </span><span style="color: #DD0000">"grapes"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">, </span><span style="color: #DD0000">"cmp"</span><span style="color: #007700">);<br /><br />while (list(</span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$value</span><span style="color: #007700">) = </span><span style="color: #0000BB">each</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">]</span><span style="color: #DD0000">: " </span><span style="color: #007700">. </span><span style="color: #0000BB">$value</span><span style="color: #007700">[</span><span style="color: #DD0000">"fruit"</span><span style="color: #007700">] . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>
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当排序多维数组时，<var class="varname"><var class="varname">$a</var></var> 和 <var class="varname"><var class="varname">$b</var></var> 包含到数组第一个索引的引用。
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</p></div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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$fruits[0]: apples
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$fruits[1]: grapes
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$fruits[2]: lemons
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-6124">
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<p><strong>Example #3
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<span class="function"><strong>usort()</strong></span> example using a member function of an object
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</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">TestObj </span><span style="color: #007700">{<br /> var </span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /><br /> function </span><span style="color: #0000BB">TestObj</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">)<br /> {<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">= </span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /> }<br /><br /> </span><span style="color: #FF8000">/* This is the static comparing function: */<br /> </span><span style="color: #007700">static function </span><span style="color: #0000BB">cmp_obj</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 /> {<br /> </span><span style="color: #0000BB">$al </span><span style="color: #007700">= </span><span style="color: #0000BB">strtolower</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">-></span><span style="color: #0000BB">name</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$bl </span><span style="color: #007700">= </span><span style="color: #0000BB">strtolower</span><span style="color: #007700">(</span><span style="color: #0000BB">$b</span><span style="color: #007700">-></span><span style="color: #0000BB">name</span><span style="color: #007700">);<br /> if (</span><span style="color: #0000BB">$al </span><span style="color: #007700">== </span><span style="color: #0000BB">$bl</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">$al </span><span style="color: #007700">> </span><span style="color: #0000BB">$bl</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 /><br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[] = new </span><span style="color: #0000BB">TestObj</span><span style="color: #007700">(</span><span style="color: #DD0000">"c"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[] = new </span><span style="color: #0000BB">TestObj</span><span style="color: #007700">(</span><span style="color: #DD0000">"b"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[] = new </span><span style="color: #0000BB">TestObj</span><span style="color: #007700">(</span><span style="color: #DD0000">"d"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, array(</span><span style="color: #DD0000">"TestObj"</span><span style="color: #007700">, </span><span style="color: #DD0000">"cmp_obj"</span><span style="color: #007700">));<br /><br />foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$item</span><span style="color: #007700">) {<br /> echo </span><span style="color: #0000BB">$item</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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b
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c
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d
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-6125">
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<p><strong>Example #4
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<span class="function"><strong>usort()</strong></span> example using a <a href="functions.anonymous.html" class="link">closure</a>
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to sort a multi-dimensional array
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</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$array</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">] = array(</span><span style="color: #DD0000">'key_a' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'z'</span><span style="color: #007700">, </span><span style="color: #DD0000">'key_b' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'c'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$array</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">] = array(</span><span style="color: #DD0000">'key_a' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'x'</span><span style="color: #007700">, </span><span style="color: #DD0000">'key_b' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'b'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$array</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">] = array(</span><span style="color: #DD0000">'key_a' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'y'</span><span style="color: #007700">, </span><span style="color: #DD0000">'key_b' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'a'</span><span style="color: #007700">);<br /><br />function </span><span style="color: #0000BB">build_sorter</span><span style="color: #007700">(</span><span style="color: #0000BB">$key</span><span style="color: #007700">) {<br /> return function (</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">) use (</span><span style="color: #0000BB">$key</span><span style="color: #007700">) {<br /> return </span><span style="color: #0000BB">strnatcmp</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">], </span><span style="color: #0000BB">$b</span><span style="color: #007700">[</span><span style="color: #0000BB">$key</span><span style="color: #007700">]);<br /> };<br />}<br /><br /></span><span style="color: #0000BB">usort</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">, </span><span style="color: #0000BB">build_sorter</span><span style="color: #007700">(</span><span style="color: #DD0000">'key_b'</span><span style="color: #007700">));<br /><br />foreach (</span><span style="color: #0000BB">$array </span><span style="color: #007700">as </span><span style="color: #0000BB">$item</span><span style="color: #007700">) {<br /> echo </span><span style="color: #0000BB">$item</span><span style="color: #007700">[</span><span style="color: #DD0000">'key_a'</span><span style="color: #007700">] . </span><span style="color: #DD0000">', ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$item</span><span style="color: #007700">[</span><span style="color: #DD0000">'key_b'</span><span style="color: #007700">] . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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y, a
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x, b
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z, c
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.usort-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="uasort.html" class="function" rel="rdfs-seeAlso">uasort()</a> - 使用用户自定义的比较函数对数组中的值进行排序并保持索引关联</span></li>
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<li class="member"><a href="array.sorting.html" class="link">数组排序函数对比</a></li>
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</ul>
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</p>
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</div>
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