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364 lines
19 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>执行匹配正则表达式</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.preg-match" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">preg_match</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">preg_match</span> — <span class="dc-title">执行匹配正则表达式</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.preg-match-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>preg_match</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$pattern</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$subject</code></span>
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[, <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$matches</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$flags</code><span class="initializer"> = 0</span></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code><span class="initializer"> = 0</span></span>
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]]] ) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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搜索<code class="parameter">subject</code>与<code class="parameter">pattern</code>给定的正则表达式的一个匹配.
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.preg-match-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">pattern</code></dt>
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<dd>
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<p class="para">
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要搜索的模式，字符串类型。
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</p>
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</dd>
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<dt>
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<code class="parameter">subject</code></dt>
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<dd>
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<p class="para">
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输入字符串。
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</p>
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</dd>
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<dt>
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<code class="parameter">matches</code></dt>
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<dd>
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<p class="para">
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如果提供了参数<code class="parameter">matches</code>，它将被填充为搜索结果。
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<var class="varname"><var class="varname">$matches[0]</var></var>将包含完整模式匹配到的文本， <var class="varname"><var class="varname">$matches[1]</var></var>
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将包含第一个捕获子组匹配到的文本，以此类推。
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</p>
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</dd>
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<dt>
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<code class="parameter">flags</code></dt>
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<dd>
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<p class="para">
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<code class="parameter">flags</code>可以被设置为以下标记值：
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<dl>
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<dt>
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<strong><code>PREG_OFFSET_CAPTURE</code></strong></dt>
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<dd>
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<p class="para">
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如果传递了这个标记，对于每一个出现的匹配返回时会附加字符串偏移量(相对于目标字符串的)。
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注意：这会改变填充到<code class="parameter">matches</code>参数的数组，使其每个元素成为一个由
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第<em>0</em>个元素是匹配到的字符串，第<em>1</em>个元素是该匹配字符串
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在目标字符串<code class="parameter">subject</code>中的偏移量。
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<div class="informalexample">
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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 />preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(foo)(bar)(baz)/'</span><span style="color: #007700">, </span><span style="color: #DD0000">'foobarbaz'</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</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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<p class="para">以上例程会输出：</p>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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[0] => Array
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(
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[0] => foobarbaz
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[1] => 0
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)
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[1] => Array
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(
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[0] => foo
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[1] => 0
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)
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[2] => Array
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(
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[0] => bar
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[1] => 3
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)
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[3] => Array
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(
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[0] => baz
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[1] => 6
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)
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)
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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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</dd>
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</dl>
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</p>
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</dd>
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<dt>
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<code class="parameter">offset</code></dt>
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<dd>
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<p class="para">
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通常，搜索从目标字符串的开始位置开始。可选参数 <code class="parameter">offset</code> 用于
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指定从目标字符串的某个位置开始搜索(单位是字节)。
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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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使用<code class="parameter">offset</code>参数不同于向<span class="function"><strong>preg_match()</strong></span>
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传递按照位置通过<em>substr($subject, $offset)</em>截取目标字符串结果，
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因为<code class="parameter">pattern</code>可以包含断言比如<em class="emphasis">^</em>， <em class="emphasis">$</em>
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或者<em class="emphasis">(?<=x)</em>。 比较：
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<div class="informalexample">
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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 />$subject </span><span style="color: #007700">= </span><span style="color: #DD0000">"abcdef"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pattern </span><span style="color: #007700">= </span><span style="color: #DD0000">'/^def/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #0000BB">$pattern</span><span style="color: #007700">, </span><span style="color: #0000BB">$subject</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</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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<p class="para">以上例程会输出：</p>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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)
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</pre></div>
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</div>
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<p class="para">
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当这个示例使用截取后传递时
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</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 />$subject </span><span style="color: #007700">= </span><span style="color: #DD0000">"abcdef"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pattern </span><span style="color: #007700">= </span><span style="color: #DD0000">'/^def/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #0000BB">$pattern</span><span style="color: #007700">, </span><span style="color: #0000BB">substr</span><span style="color: #007700">(</span><span style="color: #0000BB">$subject</span><span style="color: #007700">,</span><span style="color: #0000BB">3</span><span style="color: #007700">), </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</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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<p class="para">
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将会产生匹配
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</p>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Array
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(
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[0] => Array
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(
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[0] => def
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[1] => 0
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)
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)
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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></blockquote>
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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.preg-match-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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<span class="function"><strong>preg_match()</strong></span>返回 <code class="parameter">pattern</code> 的匹配次数。
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它的值将是0次（不匹配）或1次，因为<span class="function"><strong>preg_match()</strong></span>在第一次匹配后
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将会停止搜索。<span class="function"><a href="preg_match_all.html" class="function">preg_match_all()</a></span>不同于此，它会一直搜索<code class="parameter">subject</code>
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直到到达结尾。
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如果发生错误<span class="function"><strong>preg_match()</strong></span>返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.preg-match-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>5.3.6</td>
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<td>
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如果 <code class="parameter">offset</code> 比 <code class="parameter">subject</code> 的长度还要大则返回 <strong><code>FALSE</code></strong>。
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</td>
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</tr>
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<tr>
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<td>5.2.2</td>
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<td>
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命名子组可以接受<em>(?<name>)</em>， <em>(?'name')</em>
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以及<em>(?P<name>)</em>语法。之前版本仅接受<em>(?P<name>)</em>语法。
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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.preg-match-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-5862">
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<p><strong>Example #1 查找文本字符串"php"</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: #FF8000">//模式分隔符后的"i"标记这是一个大小写不敏感的搜索<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/php/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the web scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</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>
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</p>
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<p class="para">
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<div class="example" id="example-5863">
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<p><strong>Example #2 查找单词"word"</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: #FF8000">/* 模式中的\b标记一个单词边界，所以只有独立的单词"web"会被匹配，而不会匹配<br /> * 单词的部分内容比如"webbing" 或 "cobweb" */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/\bweb\b/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the web scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</span><span style="color: #007700">;<br />}<br /><br />if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/\bweb\b/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the website scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</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>
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</p>
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<p class="para">
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<div class="example" id="example-5864">
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<p><strong>Example #3 获取URL中的域名</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: #FF8000">//从URL中获取主机名称<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'@^(?:http://)?([^/]+)@i'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"http://www.php.net/index.html"</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$host </span><span style="color: #007700">= </span><span style="color: #0000BB">$matches</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">//获取主机名称的后面两部分<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/[^.]+\.[^.]+$/'</span><span style="color: #007700">, </span><span style="color: #0000BB">$host</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br />echo </span><span style="color: #DD0000">"domain name is: </span><span style="color: #007700">{</span><span style="color: #0000BB">$matches</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]}</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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domain name is: php.net
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-5865">
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<p><strong>Example #4 使用命名子组</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /><br />$str </span><span style="color: #007700">= </span><span style="color: #DD0000">'foobar: 2008'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(?P<name>\w+): (?P<digit>\d+)/'</span><span style="color: #007700">, </span><span style="color: #0000BB">$str</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* 下面例子在php 5.2.2(pcre 7.0)或更新版本下工作, 然而, 为了后向兼容, 上面的方式是推荐写法. */<br />// preg_match('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</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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Array
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(
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[0] => foobar: 2008
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[name] => foobar
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[1] => foobar
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[digit] => 2008
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[2] => 2008
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)
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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.preg-match-notes">
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<h3 class="title">注释</h3>
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<div class="tip"><strong class="tip">Tip</strong>
|
||
<p class="para">
|
||
如果你仅仅想要检查某个字符串是否包含另外一个字符串，不要使用<span class="function"><strong>preg_match()</strong></span>。
|
||
使用 <span class="function"><a href="strpos.html" class="function">strpos()</a></span> 会更快。
|
||
</p>
|
||
</div>
|
||
</div>
|
||
|
||
|
||
<div class="refsect1 seealso" id="refsect1-function.preg-match-seealso">
|
||
<h3 class="title">参见</h3>
|
||
<p class="para">
|
||
<ul class="simplelist">
|
||
<li class="member"><a href="pcre.pattern.html" class="link">PCRE 模式</a></li>
|
||
<li class="member"><span class="function"><a href="preg_quote.html" class="function" rel="rdfs-seeAlso">preg_quote()</a> - 转义正则表达式字符</span></li>
|
||
<li class="member"><span class="function"><a href="preg_match_all.html" class="function" rel="rdfs-seeAlso">preg_match_all()</a> - 执行一个全局正则表达式匹配</span></li>
|
||
<li class="member"><span class="function"><a href="preg_replace.html" class="function" rel="rdfs-seeAlso">preg_replace()</a> - 执行一个正则表达式的搜索和替换</span></li>
|
||
<li class="member"><span class="function"><a href="preg_split.html" class="function" rel="rdfs-seeAlso">preg_split()</a> - 通过一个正则表达式分隔字符串</span></li>
|
||
<li class="member"><span class="function"><a href="preg_last_error.html" class="function" rel="rdfs-seeAlso">preg_last_error()</a> - 返回最后一个PCRE正则执行产生的错误代码</span></li>
|
||
</ul>
|
||
</p>
|
||
</div>
|
||
|
||
|
||
</div></div></div></body></html> |