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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 数组</title>
<link rel=stylesheet href="site.css">
</head>
<script>
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<body>
<div class="example" id="arrays">
<h2><a href="./">Go by Example 中文版</a>: 数组</h2>
<table>
<tr>
<td class="docs">
<p>在 Go 中，<em>数组</em> 是一个具有编号且长度固定的元素序列。</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/ZBvk4QydAlR"><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>这里我们创建了一个刚好可以存放 5 个 <code>int</code> 元素的数组 <code>a</code>。
元素的类型和长度都是数组类型的一部分。
数组默认值是零值，对于 <code>int</code> 数组来说，元素的零值是 <code>0</code>。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">var</span> <span class="nx">a</span> <span class="p">[</span><span class="mi">5</span><span class="p">]</span><span class="kt">int</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"emp:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>我们可以使用 <code>array[index] = value</code> 语法来设置数组指定位置的值，
或者用 <code>array[index]</code> 得到值。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">a</span><span class="p">[</span><span class="mi">4</span><span class="p">]</span> <span class="p">=</span> <span class="mi">100</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"set:"</span><span class="p">,</span> <span class="nx">a</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">"get:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">[</span><span class="mi">4</span><span class="p">])</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>内置函数 <code>len</code> 可以返回数组的长度。</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">a</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>使用这个语法在一行内声明并初始化一个数组。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">b</span> <span class="o">:=</span> <span class="p">[</span><span class="mi">5</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">5</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">"dcl:"</span><span class="p">,</span> <span class="nx">b</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>数组类型是一维的，但是你可以组合构造多维的数据结构。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="kd">var</span> <span class="nx">twoD</span> <span class="p">[</span><span class="mi">2</span><span class="p">][</span><span class="mi">3</span><span class="p">]</span><span class="kt">int</span>
<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="mi">2</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">j</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">][</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="nx">j</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="s">"2d: "</span><span class="p">,</span> <span class="nx">twoD</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>注意，使用 <code>fmt.Println</code> 打印数组时，会按照 <code>[v1 v2 v3 ...]</code> 的格式打印。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> go run arrays.go
<span class="go">emp: [0 0 0 0 0]
</span><span class="go">set: [0 0 0 0 100]
</span><span class="go">get: 100
</span><span class="go">len: 5
</span><span class="go">dcl: [1 2 3 4 5]
</span><span class="go">2d: [[0 1 2] [1 2 3]]</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>在 Go 程序中，相较于数组，用得更多的是 _切片(slice)_。我们接着来看切片。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="slices.html">切片</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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