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recursion.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 递归</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'closures';
}
if (e.key == "ArrowRight") {
window.location.href = 'pointers';
}
}
</script>
<body>
<div class="example" id="recursion">
<h2><a href="./">Go by Example 中文版</a>: 递归</h2>
<table>
<tr>
<td class="docs">
<p>Go 支持 <a href="http://zh.wikipedia.org/wiki/%E9%80%92%E5%BD%92_(%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%A7%91%E5%AD%A6)"><em>递归</em></a>。
这里是一个经典的示例。</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/Bt4wcB3122x"><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="s">"fmt"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>fact</code> 函数在到达 <code>fact(0)</code> 前一直调用自身。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">fact</span><span class="p">(</span><span class="nx">n</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
<span class="k">if</span> <span class="nx">n</span> <span class="o">==</span> <span class="mi">0</span> <span class="p">{</span>
<span class="k">return</span> <span class="mi">1</span>
<span class="p">}</span>
<span class="k">return</span> <span class="nx">n</span> <span class="o">*</span> <span class="nf">fact</span><span class="p">(</span><span class="nx">n</span><span class="o">-</span><span class="mi">1</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">main</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><span class="nf">fact</span><span class="p">(</span><span class="mi">7</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>闭包也可以是递归的，但这要求在定义闭包之前用类型化的 <code>var</code> 显式声明闭包。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">var</span> <span class="nx">fib</span> <span class="kd">func</span><span class="p">(</span><span class="nx">n</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"> <span class="nx">fib</span> <span class="p">=</span> <span class="kd">func</span><span class="p">(</span><span class="nx">n</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
<span class="k">if</span> <span class="nx">n</span> <span class="p"><</span> <span class="mi">2</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">n</span>
<span class="p">}</span>
<span class="k">return</span> <span class="nf">fib</span><span class="p">(</span><span class="nx">n</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span> <span class="o">+</span> <span class="nf">fib</span><span class="p">(</span><span class="nx">n</span><span class="o">-</span><span class="mi">2</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>由于 <code>fib</code> 之前在 <code>main</code> 中声明过，
因此 Go 知道在这里用 <code>fib</code> 调用哪个函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nf">fib</span><span class="p">(</span><span class="mi">7</span><span class="p">))</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="gp">$</span> go run recursion.go
<span class="go">5040
</span><span class="go">13</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="pointers">指针</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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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func fact(n int) int {\u000A if n \u003D\u003D 0 {\u000A return 1\u000A }\u000A return n * fact(n-1)\u000A}\u000A');codeLines.push('func main() {\u000A fmt.Println(fact(7))\u000A');codeLines.push(' var fib func(n int) int\u000A');codeLines.push(' fib \u003D func(n int) int {\u000A if n \u003C 2 {\u000A return n\u000A }\u000A return fib(n-1) + fib(n-2)\u000A');codeLines.push(' }\u000A');codeLines.push(' fmt.Println(fib(7))\u000A}\u000A');codeLines.push('');
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</body>
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