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102 lines
6.7 KiB
HTML
102 lines
6.7 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>将数组的内部指针倒回一位</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.prev" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">prev</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">prev</span> — <span class="dc-title">将数组的内部指针倒回一位</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.prev-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>prev</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="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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将数组的内部指针倒回一位。
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</p>
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<p class="para">
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<span class="function"><strong>prev()</strong></span> 和
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<span class="function"><a href="next.html" class="function">next()</a></span> 的行为类似，只除了它将内部指针倒回一位而不是前移一位。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.prev-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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The input array.
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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.prev-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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返回数组内部指针指向的前一个单元的值，或当没有更多单元时返回 <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.prev-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-6113">
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<p><strong>Example #1 <span class="function"><strong>prev()</strong></span> 及相关函数用法示例</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 />$transport </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'foot'</span><span style="color: #007700">, </span><span style="color: #DD0000">'bike'</span><span style="color: #007700">, </span><span style="color: #DD0000">'car'</span><span style="color: #007700">, </span><span style="color: #DD0000">'plane'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$mode </span><span style="color: #007700">= </span><span style="color: #0000BB">current</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">); </span><span style="color: #FF8000">// $mode = 'foot';<br /></span><span style="color: #0000BB">$mode </span><span style="color: #007700">= </span><span style="color: #0000BB">next</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">); </span><span style="color: #FF8000">// $mode = 'bike';<br /></span><span style="color: #0000BB">$mode </span><span style="color: #007700">= </span><span style="color: #0000BB">next</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">); </span><span style="color: #FF8000">// $mode = 'car';<br /></span><span style="color: #0000BB">$mode </span><span style="color: #007700">= </span><span style="color: #0000BB">prev</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">); </span><span style="color: #FF8000">// $mode = 'bike';<br /></span><span style="color: #0000BB">$mode </span><span style="color: #007700">= </span><span style="color: #0000BB">end</span><span style="color: #007700">(</span><span style="color: #0000BB">$transport</span><span style="color: #007700">); </span><span style="color: #FF8000">// $mode = 'plane';<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 notes" id="refsect1-function.prev-notes">
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<h3 class="title">注释</h3>
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<div class="warning"><strong class="warning">Warning</strong><p class="simpara">此函数可能返回布尔值
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<strong><code>FALSE</code></strong>，但也可能返回等同于 <strong><code>FALSE</code></strong> 的非布尔值。请阅读 <a href="language.types.boolean.html" class="link">布尔类型</a>章节以获取更多信息。应使用
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<a href="language.operators.comparison.html" class="link">===
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运算符</a>来测试此函数的返回值。</p></div>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<span class="simpara">
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你会无法区分包含 <span class="type"><a href="language.types.boolean.html" class="type boolean">boolean</a></span> <strong><code>FALSE</code></strong> 单元的数组开头。要正确遍历可能含有空单元或者单元值为 0 的数组，参见
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<span class="function"><a href="each.html" class="function">each()</a></span> 函数。
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</span>
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</p></blockquote>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.prev-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="current.html" class="function" rel="rdfs-seeAlso">current()</a> - 返回数组中的当前单元</span></li>
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<li class="member"><span class="function"><a href="end.html" class="function" rel="rdfs-seeAlso">end()</a> - 将数组的内部指针指向最后一个单元</span></li>
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<li class="member"><span class="function"><a href="next.html" class="function" rel="rdfs-seeAlso">next()</a> - 将数组中的内部指针向前移动一位</span></li>
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<li class="member"><span class="function"><a href="reset.html" class="function" rel="rdfs-seeAlso">reset()</a> - 将数组的内部指针指向第一个单元</span></li>
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<li class="member"><span class="function"><a href="each.html" class="function" rel="rdfs-seeAlso">each()</a> - 返回数组中当前的键／值对并将数组指针向前移动一步</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> |