212 lines
8.8 KiB
Plaintext
Generated
212 lines
8.8 KiB
Plaintext
Generated
<!DOCTYPE html>
|
|
<html>
|
|
<head>
|
|
<meta charset="utf-8">
|
|
<title>Go by Example: Arrays</title>
|
|
<link rel=stylesheet href="site.css">
|
|
</head>
|
|
<script>
|
|
onkeydown = (e) => {
|
|
|
|
if (e.key == "ArrowLeft") {
|
|
window.location.href = 'switch';
|
|
}
|
|
|
|
|
|
if (e.key == "ArrowRight") {
|
|
window.location.href = 'slices';
|
|
}
|
|
|
|
}
|
|
</script>
|
|
<body>
|
|
<div class="example" id="arrays">
|
|
<h2><a href="./">Go by Example</a>: Arrays</h2>
|
|
|
|
<table>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>In Go, an <em>array</em> is a numbered sequence of elements of a
|
|
specific length.</p>
|
|
|
|
</td>
|
|
<td class="code empty leading">
|
|
|
|
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
<a href="http://play.golang.org/p/TaahifSGSwU"><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>Here we create an array <code>a</code> that will hold exactly
|
|
5 <code>int</code>s. The type of elements and length are both
|
|
part of the array’s type. By default an array is
|
|
zero-valued, which for <code>int</code>s means <code>0</code>s.</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>We can set a value at an index using the
|
|
<code>array[index] = value</code> syntax, and get a value with
|
|
<code>array[index]</code>.</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>The builtin <code>len</code> returns the length of an array.</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>Use this syntax to declare and initialize an array
|
|
in one line.</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>Array types are one-dimensional, but you can
|
|
compose types to build multi-dimensional data
|
|
structures.</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>Note that arrays appear in the form <code>[v1 v2 v3 ...]</code>
|
|
when printed with <code>fmt.Println</code>.</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>You’ll see <em>slices</em> much more often than arrays in
|
|
typical Go. We’ll look at slices next.</p>
|
|
|
|
</td>
|
|
<td class="code empty">
|
|
|
|
|
|
</td>
|
|
</tr>
|
|
|
|
</table>
|
|
|
|
|
|
<p class="next">
|
|
Next example: <a href="slices">Slices</a>.
|
|
</p>
|
|
|
|
|
|
<p class="footer">
|
|
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
|
</p>
|
|
|
|
</div>
|
|
<script>
|
|
var codeLines = [];
|
|
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push(' var a [5]int\u000A fmt.Println(\"emp:\", a)\u000A');codeLines.push(' a[4] \u003D 100\u000A fmt.Println(\"set:\", a)\u000A fmt.Println(\"get:\", a[4])\u000A');codeLines.push(' fmt.Println(\"len:\", len(a))\u000A');codeLines.push(' b :\u003D [5]int{1, 2, 3, 4, 5}\u000A fmt.Println(\"dcl:\", b)\u000A');codeLines.push(' var twoD [2][3]int\u000A for i :\u003D 0; i \u003C 2; i++ {\u000A for j :\u003D 0; j \u003C 3; j++ {\u000A twoD[i][j] \u003D i + j\u000A }\u000A }\u000A fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');
|
|
</script>
|
|
<script src="site.js" async></script>
|
|
</body>
|
|
</html>
|