218 lines
10 KiB
Plaintext
Generated
218 lines
10 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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<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="https://go.dev/play/p/_F2rYHNilKa"><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"><code><span class="line"><span class="cl"><span class="kn">package</span> <span class="nx">main</span></span></span></code></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"><code><span class="line"><span class="cl"><span class="kn">import</span> <span class="s">"fmt"</span></span></span></code></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"><code><span class="line"><span class="cl"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span></span></span></code></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"><code><span class="line"><span class="cl"> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span>
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</span></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <span class="p">}</span></span></span></code></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"><code><span class="line"><span class="cl"> <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>
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</span></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <span class="p">}</span></span></span></code></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>Another way of accomplishing the basic “do this
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N times” iteration is <code>range</code> over an integer.</p>
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</td>
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<td class="code leading">
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<pre class="chroma"><code><span class="line"><span class="cl"> <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="k">range</span> <span class="mi">3</span> <span class="p">{</span>
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</span></span><span class="line"><span class="cl"> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"range"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
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</span></span><span class="line"><span class="cl"> <span class="p">}</span></span></span></code></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"><code><span class="line"><span class="cl"> <span class="k">for</span> <span class="p">{</span>
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</span></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <span class="k">break</span>
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</span></span><span class="line"><span class="cl"> <span class="p">}</span></span></span></code></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"><code><span class="line"><span class="cl"> <span class="k">for</span> <span class="nx">n</span> <span class="o">:=</span> <span class="k">range</span> <span class="mi">6</span> <span class="p">{</span>
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</span></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <span class="k">continue</span>
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</span></span><span class="line"><span class="cl"> <span class="p">}</span>
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</span></span><span class="line"><span class="cl"> <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></span><span class="line"><span class="cl"> <span class="p">}</span>
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</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></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"><code><span class="line"><span class="cl"><span class="gp">$</span> go run for.go
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</span></span><span class="line"><span class="cl"><span class="go">1
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</span></span></span><span class="line"><span class="cl"><span class="go">2
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</span></span></span><span class="line"><span class="cl"><span class="go">3
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</span></span></span><span class="line"><span class="cl"><span class="go">0
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</span></span></span><span class="line"><span class="cl"><span class="go">1
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</span></span></span><span class="line"><span class="cl"><span class="go">2
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</span></span></span><span class="line"><span class="cl"><span class="go">range 0
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</span></span></span><span class="line"><span class="cl"><span class="go">range 1
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</span></span></span><span class="line"><span class="cl"><span class="go">range 2
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</span></span></span><span class="line"><span class="cl"><span class="go">loop
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</span></span></span><span class="line"><span class="cl"><span class="go">1
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</span></span></span><span class="line"><span class="cl"><span class="go">3
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</span></span></span><span class="line"><span class="cl"><span class="go">5</span></span></span></code></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" rel="next">If/Else</a>.
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</p>
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<p class="footer">
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Based on
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<em><a href="https://gobyexample.com/">Go by Example</a></em>
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a>
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and <a href="https://eli.thegreenplace.net">Eli Bendersky</a>,
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licensed under
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<a href="https://creativecommons.org/licenses/by/3.0/">CC BY 3.0</a>.
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<a href="https://git.inkch.xyz/inkch/gobyexample/commit/de3b5db09c9b980ba971c708a3fe522606e44572">
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Style modifications by inkch
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</a>.
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<a href="https://github.com/mmcgrana/gobyexample">Original source</a>.
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</p>
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</div>
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<script>
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