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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 字符串函数</title>
<link rel=stylesheet href="site.css">
</head>
<script>
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<div class="example" id="string-functions">
<h2><a href="./">Go by Example 中文版</a>: 字符串函数</h2>
<table>
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<td class="docs">
<p>标准库的 <code>strings</code> 包提供了很多有用的字符串相关的函数。
这儿有一些用来让你对 <code>strings</code> 包有一个初步了解的例子。</p>
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<td class="code empty leading">
</td>
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<td class="code leading">
<a href="https://play.studygolang.com/p/fxOwKEDxUyX"><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>
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<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"fmt"</span>
<span class="nx">s</span> <span class="s">"strings"</span>
<span class="p">)</span>
</pre>
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<tr>
<td class="docs">
<p>我们给 <code>fmt.Println</code> 一个较短的别名，
因为我们随后会大量的使用它。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">var</span> <span class="nx">p</span> <span class="p">=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span>
</pre>
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<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
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<tr>
<td class="docs">
<p>这是一些 <code>strings</code> 中有用的函数例子。
由于它们都是包的函数，而不是字符串对象自身的方法，
这意味着我们需要在调用函数时，将字符串作为第一个参数进行传递。
你可以在 <a href="http://golang.org/pkg/strings/"><code>strings</code></a> 包文档中找到更多的函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nf">p</span><span class="p">(</span><span class="s">"Contains: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Contains</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"es"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Count: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Count</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"t"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"HasPrefix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">HasPrefix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"te"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"HasSuffix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">HasSuffix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"st"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Index: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Index</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"e"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Join: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Join</span><span class="p">([]</span><span class="kt">string</span><span class="p">{</span><span class="s">"a"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">},</span> <span class="s">"-"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Repeat: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Repeat</span><span class="p">(</span><span class="s">"a"</span><span class="p">,</span> <span class="mi">5</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="mi">1</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Split: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">Split</span><span class="p">(</span><span class="s">"a-b-c-d-e"</span><span class="p">,</span> <span class="s">"-"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"ToLower: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">ToLower</span><span class="p">(</span><span class="s">"TEST"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"ToUpper: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nf">ToUpper</span><span class="p">(</span><span class="s">"test"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">()</span>
</pre>
</td>
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<td class="docs">
<p>虽然不是 <code>strings</code> 的函数，但仍然值得一提的是，
获取字符串长度（以字节为单位）以及通过索引获取一个字节的机制。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nf">p</span><span class="p">(</span><span class="s">"Len: "</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="s">"hello"</span><span class="p">))</span>
<span class="nf">p</span><span class="p">(</span><span class="s">"Char:"</span><span class="p">,</span> <span class="s">"hello"</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
<span class="p">}</span>
</pre>
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<tr>
<td class="docs">
<p>注意，上面的 <code>len</code> 以及索引工作在字节级别上。
Go 使用 UTF-8 编码字符串，因此通常按原样使用。
如果您可能使用多字节的字符，则需要使用可识别编码的操作。
详情请参考 <a href="https://blog.golang.org/strings">strings, bytes, runes and characters in Go</a>。</p>
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<td class="code empty">
</td>
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<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="gp">$</span> go run string-functions.go
<span class="go">Contains: true
</span><span class="go">Count: 2
</span><span class="go">HasPrefix: true
</span><span class="go">HasSuffix: true
</span><span class="go">Index: 1
</span><span class="go">Join: a-b
</span><span class="go">Repeat: aaaaa
</span><span class="go">Replace: f00
</span><span class="go">Replace: f0o
</span><span class="go">Split: [a b c d e]
</span><span class="go">ToLower: test
</span><span class="go">ToUpper: TEST</span></pre>
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<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="go">Len: 5
</span><span class="go">Char: 101</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="string-formatting">字符串格式化</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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