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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 字符串和rune类型</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'pointers';
}
if (e.key == "ArrowRight") {
window.location.href = 'structs';
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<body>
<div class="example" id="strings-and-runes">
<h2><a href="./">Go by Example 中文版</a>: 字符串和rune类型</h2>
<table>
<tr>
<td class="docs">
<p>Go语言中的字符串是一个只读的byte类型的切片。
Go语言和标准库特别对待字符串 - 作为以
<a href="https://en.wikipedia.org/wiki/UTF-8">UTF-8</a> 为编码的文本容器。
在其他语言当中， 字符串由”字符”组成。
在Go语言当中，字符的概念被称为 <code>rune</code> - 它是一个表示
Unicode 编码的整数。
<a href="https://go.dev/blog/strings">这个Go博客</a> 很好的介绍了这个主题。</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/CikqIUP5w0x"><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">"fmt"</span>
<span class="s">"unicode/utf8"</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><code>s</code> 是一个 <code>string</code> 分配了一个 literal value
表示泰语中的单词 “hello” 。
Go 字符串是 UTF-8 编码的文本。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">const</span> <span class="nx">s</span> <span class="p">=</span> <span class="s">"สวัสดี"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>因为字符串等价于 <code>[]byte</code>，
这会产生存储在其中的原始字节的长度。</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">"Len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>对字符串进行索引会在每个索引处生成原始字节值。
这个循环生成构成<code>s</code>中 Unicode 的所有字节的十六进制值。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">);</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%x "</span><span class="p">,</span> <span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">])</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">()</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>要计算字符串中有多少rune，我们可以使用<code>utf8</code>包。
注意<code>RuneCountInString</code>的运行时取决于字符串的大小。
因为它必须按顺序解码每个 UTF-8 rune。
一些泰语字符由多个 UTF-8 code point 表示，
所以这个计数的结果可能会令人惊讶。</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">"Rune count:"</span><span class="p">,</span> <span class="nx">utf8</span><span class="p">.</span><span class="nf">RuneCountInString</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>range</code> 循环专门处理字符串并解码每个 <code>rune</code> 及其在字符串中的偏移量。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">for</span> <span class="nx">idx</span><span class="p">,</span> <span class="nx">runeValue</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">s</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%#U starts at %d\n"</span><span class="p">,</span> <span class="nx">runeValue</span><span class="p">,</span> <span class="nx">idx</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>我们可以通过显式使用 <code>utf8.DecodeRuneInString</code> 函数来实现相同的迭代。</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">"\nUsing DecodeRuneInString"</span><span class="p">)</span>
<span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">);</span> <span class="nx">i</span> <span class="o">+=</span> <span class="nx">w</span> <span class="p">{</span>
<span class="nx">runeValue</span><span class="p">,</span> <span class="nx">width</span> <span class="o">:=</span> <span class="nx">utf8</span><span class="p">.</span><span class="nf">DecodeRuneInString</span><span class="p">(</span><span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">:])</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%#U starts at %d\n"</span><span class="p">,</span> <span class="nx">runeValue</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
<span class="nx">w</span> <span class="p">=</span> <span class="nx">width</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这演示了将 <code>rune</code> value 传递给函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nf">examineRune</span><span class="p">(</span><span class="nx">runeValue</span><span class="p">)</span>
<span class="p">}</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">examineRune</span><span class="p">(</span><span class="nx">r</span> <span class="kt">rune</span><span class="p">)</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>用单引号括起来的值是 <em>rune literals</em>.
我们可以直接将 <code>rune</code> value 与 rune literal 进行比较。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="k">if</span> <span class="nx">r</span> <span class="o">==</span> <span class="sc">'t'</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">"found tee"</span><span class="p">)</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span> <span class="nx">r</span> <span class="o">==</span> <span class="sc">'ส'</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">"found so sua"</span><span class="p">)</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 strings-and-runes.go
<span class="go">Len: 18
</span><span class="go">e0 b8 aa e0 b8 a7 e0 b8 b1 e0 b8 aa e0 b8 94 e0 b8 b5
</span><span class="go">Rune count: 6
</span><span class="go">U+0E2A 'ส' starts at 0
</span><span class="go">U+0E27 'ว' starts at 3
</span><span class="go">U+0E31 'ั' starts at 6
</span><span class="go">U+0E2A 'ส' starts at 9
</span><span class="go">U+0E14 'ด' starts at 12
</span><span class="go">U+0E35 'ี' starts at 15</span></pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="go">Using DecodeRuneInString
</span><span class="go">U+0E2A 'ส' starts at 0
</span><span class="go">found so sua
</span><span class="go">U+0E27 'ว' starts at 3
</span><span class="go">U+0E31 'ั' starts at 6
</span><span class="go">U+0E2A 'ส' starts at 9
</span><span class="go">found so sua
</span><span class="go">U+0E14 'ด' starts at 12
</span><span class="go">U+0E35 'ี' starts at 15</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="structs">结构体</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>
</div>
<script>
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