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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.
214 lines
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214 lines
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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: Arrays</title>
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<link rel=stylesheet href="site.css">
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</head>
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<body>
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<div class="example" id="arrays">
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<h2><a href="./">Go by Example</a>: Arrays</h2>
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<table>
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<tr>
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<td class="docs">
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<p>In Go, an <em>array</em> is a numbered sequence of elements of a
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specific length.</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/TaahifSGSwU"><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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</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>Here we create an array <code>a</code> that will hold exactly
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5 <code>int</code>s. The type of elements and length are both
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part of the array’s type. By default an array is
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zero-valued, which for <code>int</code>s means <code>0</code>s.</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">var</span> <span class="nx">a</span> <span class="p">[</span><span class="mi">5</span><span class="p">]</span><span class="kt">int</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">"emp:"</span><span class="p">,</span> <span class="nx">a</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>We can set a value at an index using the
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<code>array[index] = value</code> syntax, and get a value with
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<code>array[index]</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">a</span><span class="p">[</span><span class="mi">4</span><span class="p">]</span> <span class="p">=</span> <span class="mi">100</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">"set:"</span><span class="p">,</span> <span class="nx">a</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">"get:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">[</span><span class="mi">4</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>The builtin <code>len</code> returns the length of an array.</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">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">a</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>Use this syntax to declare and initialize an array
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in one line.</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">b</span> <span class="o">:=</span> <span class="p">[</span><span class="mi">5</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="mi">5</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">"dcl:"</span><span class="p">,</span> <span class="nx">b</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>Array types are one-dimensional, but you can
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compose types to build multi-dimensional data
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structures.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">twoD</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="kt">int</span>
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<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">2</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
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<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">j</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
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<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">][</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="nx">j</span>
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<span class="p">}</span>
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<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">"2d: "</span><span class="p">,</span> <span class="nx">twoD</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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<p>Note that arrays appear in the form <code>[v1 v2 v3 ...]</code>
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when printed with <code>fmt.Println</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="gp">$</span> go run arrays.go
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<span class="go">emp: [0 0 0 0 0]</span>
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<span class="go">set: [0 0 0 0 100]</span>
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<span class="go">get: 100</span>
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<span class="go">len: 5</span>
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<span class="go">dcl: [1 2 3 4 5]</span>
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<span class="go">2d: [[0 1 2] [1 2 3]]</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>You’ll see <em>slices</em> much more often than arrays in
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typical Go. We’ll look at slices 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="slices">Slices</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/arrays">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 main() {\u000A');codeLines.push(' var a [5]int\u000A fmt.Println(\"emp:\", a)\u000A');codeLines.push(' a[4] \u003D 100\u000A fmt.Println(\"set:\", a)\u000A fmt.Println(\"get:\", a[4])\u000A');codeLines.push(' fmt.Println(\"len:\", len(a))\u000A');codeLines.push(' b :\u003D [5]int{1, 2, 3, 4, 5}\u000A fmt.Println(\"dcl:\", b)\u000A');codeLines.push(' var twoD [2][3]int\u000A for i :\u003D 0; i \u003C 2; i++ {\u000A for j :\u003D 0; j \u003C 3; j++ {\u000A twoD[i][j] \u003D i + j\u000A }\u000A }\u000A fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');
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