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    <div class="example" id="variadic-functions">
      <h2><a href="./">Go by Example</a>: Variadic Functions</h2>
      
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            <p><a href="https://en.wikipedia.org/wiki/Variadic_function"><em>Variadic functions</em></a>
can be called with any number of trailing arguments.
For example, <code>fmt.Println</code> is a common variadic
function.</p>

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            <a href="https://go.dev/play/p/glNdE8aKPNq"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
          <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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          <pre class="chroma"><code><span class="line"><span class="cl"><span class="kn">import</span> <span class="s">&#34;fmt&#34;</span></span></span></code></pre>
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            <p>Here&rsquo;s a function that will take an arbitrary number
of <code>int</code>s as arguments.</p>

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          <pre class="chroma"><code><span class="line"><span class="cl"><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>
</span></span><span class="line"><span class="cl">    <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">&#34; &#34;</span><span class="p">)</span>
</span></span><span class="line"><span class="cl">    <span class="nx">total</span> <span class="o">:=</span> <span class="mi">0</span></span></span></code></pre>
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            <p>Within the function, the type of <code>nums</code> is
equivalent to <code>[]int</code>. We can call <code>len(nums)</code>,
iterate over it with <code>range</code>, etc.</p>

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          <pre class="chroma"><code><span class="line"><span class="cl">    <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>
</span></span><span class="line"><span class="cl">        <span class="nx">total</span> <span class="o">+=</span> <span class="nx">num</span>
</span></span><span class="line"><span class="cl">    <span class="p">}</span>
</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">total</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre>
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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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            <p>Variadic functions can be called in the usual way
with individual arguments.</p>

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          <pre class="chroma"><code><span class="line"><span class="cl">    <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></span><span class="line"><span class="cl">    <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></span></span></code></pre>
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            <p>If you already have multiple args in a slice,
apply them to a variadic function using
<code>func(slice...)</code> like this.</p>

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          <pre class="chroma"><code><span class="line"><span class="cl">    <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>
</span></span><span class="line"><span class="cl">    <span class="nf">sum</span><span class="p">(</span><span class="nx">nums</span><span class="o">...</span><span class="p">)</span>
</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre>
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          <pre class="chroma"><code><span class="line"><span class="cl"><span class="gp">$</span> go run variadic-functions.go 
</span></span><span class="line"><span class="cl"><span class="go">[1 2] 3
</span></span></span><span class="line"><span class="cl"><span class="go">[1 2 3] 6
</span></span></span><span class="line"><span class="cl"><span class="go">[1 2 3 4] 10</span></span></span></code></pre>
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            <p>Another key aspect of functions in Go is their ability
to form closures, which we&rsquo;ll look at next.</p>

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      <p class="next">
        Next example: <a href="closures">Closures</a>.
      </p>
      

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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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