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After go1.16, go will use module mode by default, even when the repository is checked out under GOPATH or in a one-off directory. Add go.mod, go.sum to keep this repo buildable without opting out of the module mode. > go mod init github.com/mmcgrana/gobyexample > go mod tidy > go mod vendor In module mode, the 'vendor' directory is special and its contents will be actively maintained by the go command. pygments aren't the dependency the go will know about, so it will delete the contents from vendor directory. Move it to `third_party` directory now. And, vendor the blackfriday package. Note: the tutorial contents are not affected by the change in go1.16 because all the examples in this tutorial ask users to run the go command with the explicit list of files to be compiled (e.g. `go run hello-world.go` or `go build command-line-arguments.go`). When the source list is provided, the go command does not have to compute the build list and whether it's running in GOPATH mode or module mode becomes irrelevant.
201 lines
6.9 KiB
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201 lines
6.9 KiB
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<!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: 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 = 'range';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'multiple-return-values';
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}
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}
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</script>
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<body>
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<div class="example" id="functions">
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<h2><a href="./">Go by Example</a>: Functions</h2>
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<table>
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<tr>
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<td class="docs">
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<p><em>Functions</em> are central in Go. We’ll learn about
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functions with a few different examples.</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/-o49-dQfGbK"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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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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<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
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</pre></div>
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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 takes two <code>int</code>s and returns
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their sum as an <code>int</code>.</p>
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</td>
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<td class="code leading">
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<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>
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</pre></div>
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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>Go requires explicit returns, i.e. it won’t
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automatically return the value of the last
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expression.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="k">return</span> <span class="nx">a</span> <span class="o">+</span> <span class="nx">b</span>
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<span class="p">}</span>
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</pre></div>
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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>When you have multiple consecutive parameters of
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the same type, you may omit the type name for the
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like-typed parameters up to the final parameter that
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declares the type.</p>
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</td>
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<td class="code leading">
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<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>
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<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>
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<span class="p">}</span>
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</pre></div>
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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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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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</pre></div>
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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>Call a function just as you’d expect, with
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<code>name(args)</code>.</p>
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</td>
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<td class="code leading">
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<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>
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<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>
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</pre></div>
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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">
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<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>
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<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>
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<span class="p">}</span>
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</pre></div>
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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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<div class="highlight"><pre><span class="gp">$</span> go run functions.go
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<span class="go">1+2 = 3</span>
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<span class="go">1+2+3 = 6</span>
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</pre></div>
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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>There are several other features to Go functions. One is
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multiple return values, 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="multiple-return-values">Multiple Return Values</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> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/functions">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 plus(a int, b int) int {\u000A');codeLines.push(' return a + b\u000A}\u000A');codeLines.push('func plusPlus(a, b, c int) int {\u000A return a + b + c\u000A}\u000A');codeLines.push('func main() {\u000A');codeLines.push(' res :\u003D plus(1, 2)\u000A fmt.Println(\"1+2 \u003D\", res)\u000A');codeLines.push(' res \u003D plusPlus(1, 2, 3)\u000A fmt.Println(\"1+2+3 \u003D\", res)\u000A}\u000A');codeLines.push('');codeLines.push('');
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</script>
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<script src="site.js" async></script>
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</body>
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</html>
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