<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example: Functions</title>
<link rel=stylesheet href="site.css">
</head>
<script type="text/javascript">
if (window.location.host == "gobyexample.com") {
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-34996217-1']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
}
</script>
<body>
<div class="example" id="functions">
<h2><a href="./">Go by Example</a>: Functions</h2>
<table>
<tr>
<td class="docs">
<p><em>Functions</em> are central in Go. We’ll learn about
functions with a few different examples.</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="http://play.golang.org/p/9Nky-Dn49f"><img title="Run code" src="play.png" class="run" /></a>
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Here’s a function that takes two <code>int</code>s and returns
their sum as an <code>int</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">plus</span><span class="p">(</span><span class="nx">a</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">b</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Go requires explicit returns, i.e. it won’t
automatically return the value of the last
expression.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="k">return</span> <span class="nx">a</span> <span class="o">+</span> <span class="nx">b</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>When you have multiple consecutive parameters of
the same type, you may omit the type name for the
like-typed parameters up to the final parameter that
declares the type.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">plusPlus</span><span class="p">(</span><span class="nx">a</span><span class="p">,</span> <span class="nx">b</span><span class="p">,</span> <span class="nx">c</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">a</span> <span class="o">+</span> <span class="nx">b</span> <span class="o">+</span> <span class="nx">c</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Call a function just as you’d expect, with
<code>name(args)</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">res</span> <span class="o">:=</span> <span class="nx">plus</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">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"1+2 ="</span><span class="p">,</span> <span class="nx">res</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<div class="highlight"><pre> <span class="nx">res</span> <span class="p">=</span> <span class="nx">plusPlus</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="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"1+2+3 ="</span><span class="p">,</span> <span class="nx">res</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="gp">$</span> go run functions.go
<span class="go">1+2 = 3</span>
<span class="go">1+2+3 = 6</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>There are several other features to Go functions. One is
multiple return values, which we’ll look at next.</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
Next example: <a href="multiple-return-values">Multiple Return Values</a>.
</p>
<p class="footer">
by <a href="https://twitter.com/mmcgrana">@mmcgrana</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
</div>
</body>
</html>