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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 正则表达式</title>
<link rel=stylesheet href="site.css">
</head>
<script>
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<body>
<div class="example" id="regular-expressions">
<h2><a href="./">Go by Example 中文版</a>: 正则表达式</h2>
<table>
<tr>
<td class="docs">
<p>Go 提供了内建的<a href="http://zh.wikipedia.org/wiki/%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F">正则表达式</a>支持。
这儿有一些在 Go 中与 regexp 相关的常见用法示例。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/Y7AyZ86mrxt"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"bytes"</span>
<span class="s">"fmt"</span>
<span class="s">"regexp"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>测试一个字符串是否符合一个表达式。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">match</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nf">MatchString</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">match</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>上面我们是直接使用字符串，但是对于一些其他的正则任务，
你需要通过 <code>Compile</code> 得到一个优化过的 <code>Regexp</code> 结构体。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">r</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nf">Compile</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>该结构体有很多方法。这是一个类似于我们前面看到的匹配测试。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">MatchString</span><span class="p">(</span><span class="s">"peach"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>查找匹配的字符串。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">FindString</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这个也是查找首次匹配的字符串，
但是它的返回值是，匹配开始和结束位置的索引，而不是匹配的内容。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"idx:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">.</span><span class="nf">FindStringIndex</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Submatch</code> 返回完全匹配和局部匹配的字符串。
例如，这里会返回匹配 <code>p([a-z]+)ch</code> 和 <code>([a-z]+)</code> 的信息。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">FindStringSubmatch</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>类似的，这个会返回完全匹配和局部匹配位置的索引。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">FindStringSubmatchIndex</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>带 <code>All</code> 的这些函数返回全部的匹配项，
而不仅仅是首次匹配项。例如查找匹配表达式全部的项。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">FindAllString</span><span class="p">(</span><span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>All</code> 同样可以对应到上面的所有函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"all:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">.</span><span class="nf">FindAllStringSubmatchIndex</span><span class="p">(</span>
<span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这些函数接收一个非负整数作为第二个参数，来限制匹配次数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">FindAllString</span><span class="p">(</span><span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="mi">2</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>上面的例子中，我们使用了字符串作为参数，
并使用了 <code>MatchString</code> 之类的方法。
我们也可以将 <code>String</code> 从函数名中去掉，并提供 <code>[]byte</code> 的参数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">Match</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"peach"</span><span class="p">)))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>创建正则表达式的全局变量时，可以使用 <code>Compile</code> 的变体 <code>MustCompile</code> 。
<code>MustCompile</code> 用 <code>panic</code> 代替返回一个错误 ，这样使用全局变量更加安全。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">r</span> <span class="p">=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nf">MustCompile</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"regexp:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>regexp</code> 包也可以用来将子字符串替换为为其它值。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nf">ReplaceAllString</span><span class="p">(</span><span class="s">"a peach"</span><span class="p">,</span> <span class="s">"<fruit>"</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Func</code> 变体允许您使用给定的函数来转换匹配的文本。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">in</span> <span class="o">:=</span> <span class="p">[]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"a peach"</span><span class="p">)</span>
<span class="nx">out</span> <span class="o">:=</span> <span class="nx">r</span><span class="p">.</span><span class="nf">ReplaceAllFunc</span><span class="p">(</span><span class="nx">in</span><span class="p">,</span> <span class="nx">bytes</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">out</span><span class="p">))</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="gp">$</span> go run regular-expressions.go
<span class="go">true
</span><span class="go">true
</span><span class="go">peach
</span><span class="go">idx: [0 5]
</span><span class="go">[peach ea]
</span><span class="go">[0 5 1 3]
</span><span class="go">[peach punch pinch]
</span><span class="go">all: [[0 5 1 3] [6 11 7 9] [12 17 13 15]]
</span><span class="go">[peach punch]
</span><span class="go">true
</span><span class="go">regexp: p([a-z]+)ch
</span><span class="go">a <fruit>
</span><span class="go">a PEACH</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>有关 Go 正则表达式的说明，请参考 <a href="http://golang.org/pkg/regexp/"><code>regexp</code></a> 包文档。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="json">JSON</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
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