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if-else.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: If/Else 分支</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
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window.location.href = 'for';
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<body>
<div class="example" id="if-else">
<h2><a href="./">Go by Example 中文版</a>: If/Else 分支</h2>
<table>
<tr>
<td class="docs">
<p><code>if</code> 和 <code>else</code> 分支结构在 Go 中非常直接。</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/R3tOwlnRJwz"><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">
</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>这里是一个基本的例子。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">if</span> <span class="mi">7</span><span class="o">%</span><span class="mi">2</span> <span class="o">==</span> <span class="mi">0</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">"7 is even"</span><span class="p">)</span>
<span class="p">}</span> <span class="k">else</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">"7 is odd"</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>你可以不要 <code>else</code> 只用 <code>if</code> 语句。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">if</span> <span class="mi">8</span><span class="o">%</span><span class="mi">4</span> <span class="o">==</span> <span class="mi">0</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">"8 is divisible by 4"</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>在条件语句之前可以有一个声明语句；在这里声明的变量可以在这个语句所有的条件分支中使用。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">if</span> <span class="nx">num</span> <span class="o">:=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">num</span> <span class="p"><</span> <span class="mi">0</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">num</span><span class="p">,</span> <span class="s">"is negative"</span><span class="p">)</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span> <span class="nx">num</span> <span class="p"><</span> <span class="mi">10</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">num</span><span class="p">,</span> <span class="s">"has 1 digit"</span><span class="p">)</span>
<span class="p">}</span> <span class="k">else</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">num</span><span class="p">,</span> <span class="s">"has multiple digits"</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>注意，在 Go 中，条件语句的圆括号不是必需的，但是花括号是必需的。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="gp">$</span> go run if-else.go
<span class="go">7 is odd
</span><span class="go">8 is divisible by 4
</span><span class="go">9 has 1 digit</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Go 没有<a href="http://en.wikipedia.org/wiki/%3F:">三目运算符</a>，
即使是基本的条件判断，依然需要使用完整的 <code>if</code> 语句。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="switch.html">Switch 分支结构</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>
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