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102 lines
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HTML
102 lines
8.7 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>正则表达式替换</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.ereg-replace" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">ereg_replace</h1>
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<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">ereg_replace</span> — <span class="dc-title">正则表达式替换</span></p>
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</div>
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<div class="refsect1 unknown-seealsp" id="refsect1-function.ereg-replace-unknown-seealsp">
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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>ereg_replace</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$pattern</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$replacement</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$string</code></span>
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) : <span class="type">string</span></div>
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<p class="simpara">
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本函数在 <code class="parameter">string</code> 中扫描与
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<code class="parameter">pattern</code> 匹配的部分，并将其替换为
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<code class="parameter">replacement</code>。
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</p>
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<p class="simpara">
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返回替换后的字符串。（如果没有可供替换的匹配项则会返回原字符串。）
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</p>
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<p class="simpara">
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如果 <code class="parameter">pattern</code>
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包含有括号内的子串，则 <code class="parameter">replacement</code>
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可以包含形如
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<em>\\<span class="replaceable">digit</span></em>
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的子串，这些子串将被替换为数字表示的的第几个括号内的子串；<em>\\0</em>
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则包含了字符串的整个内容。最多可以用九个子串。括号可以嵌套，此情形下以左圆括号来计算顺序。
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</p>
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<p class="simpara">
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如果未在 <code class="parameter">string</code>
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中找到匹配项，则
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<code class="parameter">string</code> 将原样返回。
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</p>
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<p class="para">
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例如，下面的代码片断输出
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"This was a test" 三次：
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</p>
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<p class="para">
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<div class="example" id="example-5881">
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<p><strong>Example #1 <span class="function"><strong>ereg_replace()</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 />$string </span><span style="color: #007700">= </span><span style="color: #DD0000">"This is a test"</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">str_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">" is"</span><span style="color: #007700">, </span><span style="color: #DD0000">" was"</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">ereg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">"( )is"</span><span style="color: #007700">, </span><span style="color: #DD0000">"\\1was"</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">ereg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">"(( )is)"</span><span style="color: #007700">, </span><span style="color: #DD0000">"\\2was"</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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要注意的一点是如果在 <code class="parameter">replacement</code>
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参数中使用了整数值，则可能得不到所期望的结果。这是因为
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<span class="function"><strong>ereg_replace()</strong></span> 将把数字作为字符的序列值来解释并应用之。例如：
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</p>
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<p class="para">
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<div class="example" id="example-5882">
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<p><strong>Example #2 <span class="function"><strong>ereg_replace()</strong></span> 例子</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* 不能产生出期望的结果 */<br /></span><span style="color: #0000BB">$num </span><span style="color: #007700">= </span><span style="color: #0000BB">4</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$string </span><span style="color: #007700">= </span><span style="color: #DD0000">"This string has four words."</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$string </span><span style="color: #007700">= </span><span style="color: #0000BB">ereg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">'four'</span><span style="color: #007700">, </span><span style="color: #0000BB">$num</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$string</span><span style="color: #007700">; </span><span style="color: #FF8000">/* Output: 'This string has words.' */<br /><br />/* 本例工作正常 */<br /></span><span style="color: #0000BB">$num </span><span style="color: #007700">= </span><span style="color: #DD0000">'4'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$string </span><span style="color: #007700">= </span><span style="color: #DD0000">"This string has four words."</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$string </span><span style="color: #007700">= </span><span style="color: #0000BB">ereg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">'four'</span><span style="color: #007700">, </span><span style="color: #0000BB">$num</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$string</span><span style="color: #007700">; </span><span style="color: #FF8000">/* Output: 'This string has 4 words.' */<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-5883">
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<p><strong>Example #3 将 URL 替换为超连接</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$text </span><span style="color: #007700">= </span><span style="color: #0000BB">ereg_replace</span><span style="color: #007700">(</span><span style="color: #DD0000">"[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"<a href=\"\\0\">\\0</a>"</span><span style="color: #007700">, </span><span style="color: #0000BB">$text</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 class="tip"><strong class="tip">Tip</strong>
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<p class="para">
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<span class="function"><a href="preg_replace.html" class="function">preg_replace()</a></span> 函数使用了
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Perl 兼容正则表达式语法，通常是比
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<span class="function"><strong>ereg_replace()</strong></span> 更快的替代方案。
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</p>
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</div>
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<p class="para">
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参见 <span class="function"><a href="ereg.html" class="function">ereg()</a></span>，<span class="function"><a href="eregi.html" class="function">eregi()</a></span>，<span class="function"><a href="eregi_replace.html" class="function">eregi_replace()</a></span>，<span class="function"><a href="str_replace.html" class="function">str_replace()</a></span>
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和 <span class="function"><a href="preg_match.html" class="function">preg_match()</a></span>。
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</p>
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</div>
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</div></div></div></body></html> |