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variadic-functions
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variadic-functions
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<!DOCTYPE html>
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<title>Go by Example: Variadic Functions</title>
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<div class="example" id="variadic-functions">
<h2><a href="./">Go by Example</a>: Variadic Functions</h2>
<a href="http://play.golang.org/p/wRPLOM1VIH"><img height="16" width="16" title="Run code" src="play.png" style="float:right" /></a>
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<p><a href="http://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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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
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<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
</pre></div>
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<p>Here’s a function that will take an arbitrary number
of <code>ints</code> as arguments.</p>
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">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 class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">nums</span><span class="p">,</span> <span class="s">" "</span><span class="p">)</span>
<span class="nx">total</span> <span class="o">:=</span> <span class="mi">0</span>
<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 class="nx">total</span> <span class="o">+=</span> <span class="nx">num</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">total</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
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<p>Variadic functions can be called in the usual way
with individual arguments.</p>
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<div class="highlight"><pre> <span class="nx">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="nx">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>
</pre></div>
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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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<div class="highlight"><pre> <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 class="nx">sum</span><span class="p">(</span><span class="nx">nums</span><span class="o">...</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
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<div class="highlight"><pre><span class="gp">$</span> go run variadic-functions.go
<span class="go">[1 2] 3</span>
<span class="go">[1 2 3] 6</span>
<span class="go">[1 2 3 4] 10</span>
</pre></div>
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<p>Another key aspect of functions in Go is their ability
to form closures, which we’ll look at next.</p>
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<p class="next">
Next example: <a href="closures">Closures</a>.
</p>
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