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<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<title>Go by Example 中文:Panic</title>
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<div class="example" id="panic">
<h2><a href="../">Go by Example 中文</a>：Panic</h2>
<table>
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<td class="docs">
<p><code>panic</code> 意味着有些出乎意料的错误发生。通常我们用它来表示程序正常运行中不应该出现的，后者我么没有处理好的错误。</p>
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<a href="http://play.golang.org/p/nWYPMt6EBR"><img title="Run code" src="../play.png" class="run" /></a>
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
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<div class="highlight"><pre><span class="kn">import</span> <span class="s">"os"</span>
</pre></div>
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
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<p>我们将在真个网站中使用 panic 来检查预期外的错误。这个是唯一一个为 panic 准备的例子。</p>
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<div class="highlight"><pre> <span class="nb">panic</span><span class="p">(</span><span class="s">"a problem"</span><span class="p">)</span>
</pre></div>
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<p>panic 的一个基本用法就是在一个函数返回了错误值但是我们并不知道（或者不想）处理时终止运行。这里是一个在创建一个新文件时返回异常错误时的<code>panic</code> 用法。</p>
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<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Create</span><span class="p">(</span><span class="s">"/tmp/file"</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
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<p>运行程序将会引起 panic，输出一个错误消息和 Go 运行时栈信息，并且返回一个非零的状态码。</p>
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<div class="highlight"><pre><span class="gp">$</span> go run panic.go
<span class="go">panic: a problem</span>
</pre></div>
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<div class="highlight"><pre><span class="go">goroutine 1 [running]:</span>
<span class="go">main.main()</span>
<span class="go"> /.../panic.go:12 +0x47</span>
<span class="go">...</span>
<span class="go">exit status 2</span>
</pre></div>
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<p>注意，不像有些语言中处理多个错误那样，在 Go 中习惯使用错误码返回任意可能的值。</p>
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<p class="next">
下一个例子: <a href="../defer/">Defer</a>.
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 编写 | <a href="https://plus.google.com/u/0/113729799374513477039">everyx</a> 翻译 | <a href="https://github.com/everyx/gobyexample">项目地址</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
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