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349 lines
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349 lines
21 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>执行一个正则表达式的搜索和替换</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-replace" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">preg_replace</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">preg_replace</span> — <span class="dc-title">执行一个正则表达式的搜索和替换</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.preg-replace-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_replace</strong></span>
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( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$pattern</code></span>
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, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$replacement</code></span>
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, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$subject</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$limit</code><span class="initializer"> = -1</span></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter reference">&$count</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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搜索<code class="parameter">subject</code>中匹配<code class="parameter">pattern</code>的部分，
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以<code class="parameter">replacement</code>进行替换。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.preg-replace-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。可以使一个字符串或字符串数组。
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</p>
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<p class="para">
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可以使用一些<a href="reference.pcre.pattern.modifiers.html" class="link">PCRE修饰符</a>。
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</p>
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</dd>
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<dt>
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<code class="parameter">replacement</code></dt>
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<dd>
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<p class="para">
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用于替换的字符串或字符串数组。如果这个参数是一个字符串，并且<code class="parameter">pattern</code>
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是一个数组，那么所有的模式都使用这个字符串进行替换。如果<code class="parameter">pattern</code>和<code class="parameter">replacement</code>
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都是数组，每个<code class="parameter">pattern</code>使用<code class="parameter">replacement</code>中对应的
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元素进行替换。如果<code class="parameter">replacement</code>中的元素比<code class="parameter">pattern</code>中的少，
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多出来的<code class="parameter">pattern</code>使用空字符串进行替换。
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</p>
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<p class="para">
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<code class="parameter">replacement</code>中可以包含后向引用<em>\\<span class="replaceable">n</span></em>
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或<em>$<span class="replaceable">n</span></em>，语法上首选后者。 每个
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这样的引用将被匹配到的第<span class="replaceable">n</span>个捕获子组捕获到的文本替换。 <span class="replaceable">n</span>
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可以是0-99，<em>\\0</em>和<em>$0</em>代表完整的模式匹配文本。
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捕获子组的序号计数方式为：代表捕获子组的左括号从左到右， 从1开始数。如果要在<code class="parameter">replacement</code>
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中使用反斜线，必须使用4个(<em>"\\\\"</em>，译注：因为这首先是php的字符串，经过转义后，是两个，再经过
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正则表达式引擎后才被认为是一个原文反斜线)。
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</p>
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<p class="para">
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当在替换模式下工作并且后向引用后面紧跟着需要是另外一个数字(比如：在一个匹配模式后紧接着增加一个原文数字)，
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不能使用<em>\\1</em>这样的语法来描述后向引用。比如， <em>\\11</em>将会使<span class="function"><strong>preg_replace()</strong></span>
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不能理解你希望的是一个<em>\\1</em>后向引用紧跟一个原文<em>1</em>，还是
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一个<em>\\11</em>后向引用后面不跟任何东西。 这种情况下解决方案是使用<em>${1}1</em>。
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这创建了一个独立的<em>$1</em>后向引用, 一个独立的原文<em>1</em>。
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</p>
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<p class="para">
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当使用被弃用的 <em>e</em> 修饰符时, 这个函数会转义一些字符(即：<em>'</em>、<em>"</em>、
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<em>\</em> 和 NULL) 然后进行后向引用替换。当这些完成后请确保后向引用解析完后没有单引号或
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双引号引起的语法错误(比如： <em>'strlen(\'$1\')+strlen("$2")'</em>)。确保符合PHP的
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<a href="language.types.string.html" class="link">字符串语法</a>，并且符合eval语法。因为在完成替换后，
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引擎会将结果字符串作为php代码使用eval方式进行评估并将返回值作为最终参与替换的字符串。
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</p>
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</dd>
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<dt>
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<code class="parameter">subject</code></dt>
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<dd>
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<p class="para">
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要进行搜索和替换的字符串或字符串数组。
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</p>
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<p class="para">
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如果<code class="parameter">subject</code>是一个数组，搜索和替换回在<code class="parameter">subject</code>
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的每一个元素上进行, 并且返回值也会是一个数组。
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</p>
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</dd>
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<dt>
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<code class="parameter">limit</code></dt>
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<dd>
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<p class="para">
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每个模式在每个<code class="parameter">subject</code>上进行替换的最大次数。默认是
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<em>-1</em>(无限)。
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</p>
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</dd>
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<dt>
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<code class="parameter">count</code></dt>
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<dd>
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<p class="para">
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如果指定，将会被填充为完成的替换次数。
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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.preg-replace-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<code class="parameter">subject</code>是一个数组， <span class="function"><strong>preg_replace()</strong></span>返回一个数组，
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其他情况下返回一个字符串。
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</p>
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<p class="para">
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如果匹配被查找到，替换后的<code class="parameter">subject</code>被返回，其他情况下
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返回没有改变的 <code class="parameter">subject</code>。如果发生错误，返回 <strong><code>NULL</code></strong> 。
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</p>
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</div>
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<div class="refsect1 errors" id="refsect1-function.preg-replace-errors">
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<h3 class="title">错误／异常</h3>
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<p class="para">
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PHP 5.5.0 起， 传入 "\e" 修饰符的时候，会产生一个 <strong><code>E_DEPRECATED</code></strong> 错误； PHP 7.0.0 起，会产生 <strong><code>E_WARNING</code></strong> 错误，同时 "\e" 也无法起效。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.preg-replace-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>7.0.0</td>
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<td>
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不再支持 <em>/e</em>修饰符。
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请用 <span class="function"><a href="preg_replace_callback.html" class="function">preg_replace_callback()</a></span> 代替。
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</td>
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</tr>
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<tr>
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<td>5.5.0</td>
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<td>
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<em>/e</em> 修饰符已经被弃用了。使用
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<span class="function"><a href="preg_replace_callback.html" class="function">preg_replace_callback()</a></span> 代替。参见文档中 <a href="reference.pcre.pattern.modifiers.html#reference.pcre.pattern.modifiers.eval" class="link">PREG_REPLACE_EVAL</a> 关于安全风险的更多信息。
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</td>
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</tr>
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<tr>
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<td>5.1.0</td>
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<td>
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增加参数<code class="parameter">count</code>.
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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-replace-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-5872">
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<p><strong>Example #1 使用后向引用紧跟数值原文</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 />$string </span><span style="color: #007700">= </span><span style="color: #DD0000">'April 15, 2003'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pattern </span><span style="color: #007700">= </span><span style="color: #DD0000">'/(\w+) (\d+), (\d+)/i'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$replacement </span><span style="color: #007700">= </span><span style="color: #DD0000">'${1}1,$3'</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(</span><span style="color: #0000BB">$pattern</span><span style="color: #007700">, </span><span style="color: #0000BB">$replacement</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</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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April1,2003
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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-5873">
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<p><strong>Example #2 <span class="function"><strong>preg_replace()</strong></span>中使用基于索引的数组</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 />$string </span><span style="color: #007700">= </span><span style="color: #DD0000">'The quick brown fox jumps over the lazy dog.'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$patterns </span><span style="color: #007700">= array();<br /></span><span style="color: #0000BB">$patterns</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #DD0000">'/quick/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$patterns</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">] = </span><span style="color: #DD0000">'/brown/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$patterns</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">] = </span><span style="color: #DD0000">'/fox/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$replacements </span><span style="color: #007700">= array();<br /></span><span style="color: #0000BB">$replacements</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">] = </span><span style="color: #DD0000">'bear'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$replacements</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">] = </span><span style="color: #DD0000">'black'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$replacements</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #DD0000">'slow'</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(</span><span style="color: #0000BB">$patterns</span><span style="color: #007700">, </span><span style="color: #0000BB">$replacements</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</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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The bear black slow jumps over the lazy dog.
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</pre></div>
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</div>
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<div class="example-contents"><p>
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对模式和替换内容按key进行排序我们可以得到期望的结果。
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</p></div>
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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 />ksort</span><span style="color: #007700">(</span><span style="color: #0000BB">$patterns</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">ksort</span><span style="color: #007700">(</span><span style="color: #0000BB">$replacements</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(</span><span style="color: #0000BB">$patterns</span><span style="color: #007700">, </span><span style="color: #0000BB">$replacements</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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The slow black bear jumps over the lazy dog.
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-5874">
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<p><strong>Example #3 替换一些值</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$patterns </span><span style="color: #007700">= array (</span><span style="color: #DD0000">'/(19|20)(\d{2})-(\d{1,2})-(\d{1,2})/'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'/^\s*{(\w+)}\s*=/'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$replace </span><span style="color: #007700">= array (</span><span style="color: #DD0000">'\3/\4/\1\2'</span><span style="color: #007700">, </span><span style="color: #DD0000">'$\1 ='</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(</span><span style="color: #0000BB">$patterns</span><span style="color: #007700">, </span><span style="color: #0000BB">$replace</span><span style="color: #007700">, </span><span style="color: #DD0000">'{startDate} = 1999-5-27'</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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$startDate = 5/27/1999
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-5875">
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<p><strong>Example #4 剥离空白字符</strong></p>
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<div class="example-contents"><p>
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这个例子剥离多余的空白字符
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</p></div>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$str </span><span style="color: #007700">= </span><span style="color: #DD0000">'foo o'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">= </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">'/\s\s+/'</span><span style="color: #007700">, </span><span style="color: #DD0000">' '</span><span style="color: #007700">, </span><span style="color: #0000BB">$str</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// 将会改变为'foo o'<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">$str</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-5876">
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<p><strong>Example #5 使用参数<code class="parameter">count</code></strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$count </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /><br />echo </span><span style="color: #0000BB">preg_replace</span><span style="color: #007700">(array(</span><span style="color: #DD0000">'/\d/'</span><span style="color: #007700">, </span><span style="color: #DD0000">'/\s/'</span><span style="color: #007700">), </span><span style="color: #DD0000">'*'</span><span style="color: #007700">, </span><span style="color: #DD0000">'xp 4 to'</span><span style="color: #007700">, -</span><span style="color: #0000BB">1 </span><span style="color: #007700">, </span><span style="color: #0000BB">$count</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$count</span><span style="color: #007700">; </span><span style="color: #FF8000">//3<br /></span><span style="color: #0000BB">?></span>
|
||
</span>
|
||
</pre></div>
|
||
</div>
|
||
|
||
<div class="example-contents"><p>以上例程会输出：</p></div>
|
||
<div class="example-contents screen">
|
||
<div class="cdata"><pre>
|
||
xp***to
|
||
3
|
||
</pre></div>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
</div>
|
||
</div>
|
||
</p>
|
||
</div>
|
||
|
||
|
||
<div class="refsect1 notes" id="refsect1-function.preg-replace-notes">
|
||
<h3 class="title">注释</h3>
|
||
<blockquote class="note"><p><strong class="note">Note</strong>:
|
||
<p class="para">
|
||
当使用数组形式的<code class="parameter">pattern</code>和<code class="parameter">replacement</code>时,
|
||
将会按照key在数组中出现的顺序进行处理. 这<em class="emphasis">不一定</em>和数组的索引顺序一致.
|
||
如果你期望使用索引对等方式用<code class="parameter">replacement</code>对<code class="parameter">pattern</code>
|
||
进行替换, 你可以在调用<span class="function"><strong>preg_replace()</strong></span>之前对两个数组各进行一次<span class="function"><a href="ksort.html" class="function">ksort()</a></span>排序.
|
||
</p>
|
||
</p></blockquote>
|
||
</div>
|
||
|
||
|
||
<div class="refsect1 seealso" id="refsect1-function.preg-replace-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_filter.html" class="function" rel="rdfs-seeAlso">preg_filter()</a> - 执行一个正则表达式搜索和替换</span></li>
|
||
<li class="member"><span class="function"><a href="preg_match.html" class="function" rel="rdfs-seeAlso">preg_match()</a> - 执行匹配正则表达式</span></li>
|
||
<li class="member"><span class="function"><a href="preg_replace_callback.html" class="function" rel="rdfs-seeAlso">preg_replace_callback()</a> - 执行一个正则表达式搜索并且使用一个回调进行替换</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> |