200 lines
7.1 KiB
Plaintext
Generated
200 lines
7.1 KiB
Plaintext
Generated
<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: For</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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window.location.href = 'constants';
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window.location.href = 'if-else';
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<body>
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<div class="example" id="for">
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<h2><a href="./">Go by Example</a>: For</h2>
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<table>
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<tr>
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<td class="docs">
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<p><code>for</code> is Go’s only looping construct. Here are
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some basic types of <code>for</code> loops.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/2-4H-ArwHHS"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kn">import</span> <span class="s">"fmt"</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>The most basic type, with a single condition.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span>
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<span class="k">for</span> <span class="nx">i</span> <span class="o"><=</span> <span class="mi">3</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">i</span><span class="p">)</span>
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<span class="nx">i</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="mi">1</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>A classic initial/condition/after <code>for</code> loop.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">7</span><span class="p">;</span> <span class="nx">j</span> <span class="o"><=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">j</span><span class="p">)</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p><code>for</code> without a condition will loop repeatedly
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until you <code>break</code> out of the loop or <code>return</code> from
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the enclosing function.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="k">for</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"loop"</span><span class="p">)</span>
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<span class="k">break</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>You can also <code>continue</code> to the next iteration of
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the loop.</p>
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</td>
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<td class="code">
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<pre class="chroma">
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<span class="k">for</span> <span class="nx">n</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">n</span> <span class="o"><=</span> <span class="mi">5</span><span class="p">;</span> <span class="nx">n</span><span class="o">++</span> <span class="p">{</span>
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<span class="k">if</span> <span class="nx">n</span><span class="o">%</span><span class="mi">2</span> <span class="o">==</span> <span class="mi">0</span> <span class="p">{</span>
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<span class="k">continue</span>
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<span class="p">}</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">n</span><span class="p">)</span>
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<span class="p">}</span>
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<span class="p">}</span>
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</pre>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<pre class="chroma"><span class="gp">$</span> go run for.go
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<span class="go">1
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</span><span class="go">2
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</span><span class="go">3
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</span><span class="go">7
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</span><span class="go">8
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</span><span class="go">9
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</span><span class="go">loop
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</span><span class="go">1
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</span><span class="go">3
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</span><span class="go">5</span></pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>We’ll see some other <code>for</code> forms later when we look at
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<code>range</code> statements, channels, and other data
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structures.</p>
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</td>
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<td class="code empty">
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="if-else">If/Else</a>.
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</p>
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<p class="footer">
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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>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push(' i :\u003D 1\u000A for i \u003C\u003D 3 {\u000A fmt.Println(i)\u000A i \u003D i + 1\u000A }\u000A');codeLines.push(' for j :\u003D 7; j \u003C\u003D 9; j++ {\u000A fmt.Println(j)\u000A }\u000A');codeLines.push(' for {\u000A fmt.Println(\"loop\")\u000A break\u000A }\u000A');codeLines.push(' for n :\u003D 0; n \u003C\u003D 5; n++ {\u000A if n%2 \u003D\u003D 0 {\u000A continue\u000A }\u000A fmt.Println(n)\u000A }\u000A}\u000A');codeLines.push('');codeLines.push('');
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</script>
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