177 lines
6.4 KiB
Plaintext
Generated
177 lines
6.4 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: Variadic Functions</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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if (e.key == "ArrowLeft") {
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window.location.href = 'multiple-return-values';
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if (e.key == "ArrowRight") {
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window.location.href = 'closures';
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<body>
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<div class="example" id="variadic-functions">
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<h2><a href="./">Go by Example</a>: Variadic Functions</h2>
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<table>
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<tr>
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<td class="docs">
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<p><a href="http://en.wikipedia.org/wiki/Variadic_function"><em>Variadic functions</em></a>
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can be called with any number of trailing arguments.
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For example, <code>fmt.Println</code> is a common variadic
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function.</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/Ua6kZOMabBp"><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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<p>Here’s a function that will take an arbitrary number
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of <code>int</code>s as arguments.</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="kd">func</span> <span class="nf">sum</span><span class="p">(</span><span class="nx">nums</span> <span class="o">...</span><span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Print</span><span class="p">(</span><span class="nx">nums</span><span class="p">,</span> <span class="s">" "</span><span class="p">)</span>
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<span class="nx">total</span> <span class="o">:=</span> <span class="mi">0</span>
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<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">num</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">nums</span> <span class="p">{</span>
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<span class="nx">total</span> <span class="o">+=</span> <span class="nx">num</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">total</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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</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>Variadic functions can be called in the usual way
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with individual arguments.</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="nf">sum</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
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<span class="nf">sum</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>
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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>If you already have multiple args in a slice,
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apply them to a variadic function using
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<code>func(slice...)</code> like this.</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="nx">nums</span> <span class="o">:=</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>
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<span class="nf">sum</span><span class="p">(</span><span class="nx">nums</span><span class="o">...</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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</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 variadic-functions.go
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<span class="go">[1 2] 3
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</span><span class="go">[1 2 3] 6
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</span><span class="go">[1 2 3 4] 10</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>Another key aspect of functions in Go is their ability
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to form closures, which we’ll look at next.</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="closures">Closures</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 sum(nums ...int) {\u000A fmt.Print(nums, \" \")\u000A total :\u003D 0\u000A for _, num :\u003D range nums {\u000A total +\u003D num\u000A }\u000A fmt.Println(total)\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push(' sum(1, 2)\u000A sum(1, 2, 3)\u000A');codeLines.push(' nums :\u003D []int{1, 2, 3, 4}\u000A sum(nums...)\u000A}\u000A');codeLines.push('');codeLines.push('');
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