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135 lines
5.6 KiB
HTML
135 lines
5.6 KiB
HTML
<!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>从数组中随机取出一个或多个单元</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.array-rand" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">array_rand</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">array_rand</span> — <span class="dc-title">
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从数组中随机取出一个或多个单元
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</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.array-rand-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>array_rand</strong></span>
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( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$num</code><span class="initializer"> = 1</span></span>
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] ) : <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span></div>
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<p class="para rdfs-comment">
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从数组中取出一个或多个随机的单元，并返回随机条目的一个或多个键。
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它使用了伪随机数产生算法，所以不适合密码学场景，
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.array-rand-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">num</code></dt>
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<dd>
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<p class="para">
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指明了你想取出多少个单元。
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</p>
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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.array-rand-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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如果只取出一个，<span class="function"><strong>array_rand()</strong></span>
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返回随机单元的键名。
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否则就返回包含随机键名的数组。
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完成后，就可以根据随机的键获取数组的随机值。
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取出数量如果超过 array 的长度，就会导致 <strong><code>E_WARNING</code></strong> 错误，并返回 NULL。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.array-rand-changelog">
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<h3 class="title">更新日志</h3>
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<p class="para">
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<table class="doctable informaltable">
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<thead>
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<tr>
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<th>版本</th>
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<th>说明</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>7.1.0</td>
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<td>
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<a href="migration71.incompatible.html#migration71.incompatible.rand_srand_aliases" class="link">内置的随机数生成算法从 libc rand 函数改成<a href="http://www.math.sci.hiroshima_u.ac.jp/~m_mat/MT/emt.html" class="link external">» 梅森旋转</a> 伪随机数生成算法。</a>
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</td>
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</tr>
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<tr>
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<td>5.2.10</td>
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<td>
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The resulting array of keys is no longer shuffled.
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</td>
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</tr>
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</tbody>
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</table>
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.array-rand-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-6058">
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<p><strong>Example #1 <span class="function"><strong>array_rand()</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 />$input </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"Neo"</span><span style="color: #007700">, </span><span style="color: #DD0000">"Morpheus"</span><span style="color: #007700">, </span><span style="color: #DD0000">"Trinity"</span><span style="color: #007700">, </span><span style="color: #DD0000">"Cypher"</span><span style="color: #007700">, </span><span style="color: #DD0000">"Tank"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$rand_keys </span><span style="color: #007700">= </span><span style="color: #0000BB">array_rand</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$input</span><span style="color: #007700">[</span><span style="color: #0000BB">$rand_keys</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]] . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">$input</span><span style="color: #007700">[</span><span style="color: #0000BB">$rand_keys</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">]] . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<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>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.array-rand-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="shuffle.html" class="function" rel="rdfs-seeAlso">shuffle()</a> - 打乱数组</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |