196 lines
11 KiB
Plaintext
196 lines
11 KiB
Plaintext
<!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: String Functions</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="string-functions">
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<h2><a href="./">Go by Example</a>: String Functions</h2>
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<table>
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<tr>
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<td class="docs">
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<p>The standard library’s <code>strings</code> package provides many
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useful string-related functions. Here are some examples
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to give you a sense of the package.</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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<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/Vn4D3y4_711"><img title="Run code" class="run" src="data:image/png;base64,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" /></a>
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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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<td class="docs">
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="nx">s</span> <span class="s">"strings"</span>
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<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>We alias <code>fmt.Println</code> to a shorter name as we’ll use
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it a lot below.</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">p</span> <span class="p">=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</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’s a sample of the functions available in
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<code>strings</code>. Since these are functions from the
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package, not methods on the string object itself,
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we need pass the string in question as the first
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argument to the function. You can find more
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functions in the <a href="http://golang.org/pkg/strings/"><code>strings</code></a>
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package docs.</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">p</span><span class="p">(</span><span class="s">"Contains: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Contains</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"es"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Count: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Count</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"t"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"HasPrefix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasPrefix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"te"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"HasSuffix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasSuffix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"st"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Index: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Index</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"e"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Join: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Join</span><span class="p">([]</span><span class="kt">string</span><span class="p">{</span><span class="s">"a"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">},</span> <span class="s">"-"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Repeat: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Repeat</span><span class="p">(</span><span class="s">"a"</span><span class="p">,</span> <span class="mi">5</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="mi">1</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Split: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="s">"a-b-c-d-e"</span><span class="p">,</span> <span class="s">"-"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"ToLower: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToLower</span><span class="p">(</span><span class="s">"TEST"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"ToUpper: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">(</span><span class="s">"test"</span><span class="p">))</span>
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<span class="nx">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>Not part of <code>strings</code>, but worth mentioning here, are
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the mechanisms for getting the length of a string in
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bytes and getting a byte by index.</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">p</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="s">"hello"</span><span class="p">))</span>
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<span class="nx">p</span><span class="p">(</span><span class="s">"Char:"</span><span class="p">,</span> <span class="s">"hello"</span><span class="p">[</span><span class="mi">1</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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<tr>
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<td class="docs">
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<p>Note that <code>len</code> and indexing above work at the byte level.
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Go uses UTF-8 encoded strings, so this is often useful
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as-is. If you’re working with potentially multi-byte
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characters you’ll want to use encoding-aware operations.
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See <a href="https://blog.golang.org/strings">strings, bytes, runes and characters in Go</a>
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for more information.</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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<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 string-functions.go
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<span class="go">Contains: true</span>
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<span class="go">Count: 2</span>
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<span class="go">HasPrefix: true</span>
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<span class="go">HasSuffix: true</span>
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<span class="go">Index: 1</span>
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<span class="go">Join: a-b</span>
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<span class="go">Repeat: aaaaa</span>
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<span class="go">Replace: f00</span>
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<span class="go">Replace: f0o</span>
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<span class="go">Split: [a b c d e]</span>
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<span class="go">ToLower: test</span>
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<span class="go">ToUpper: TEST</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="go">Len: 5</span>
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<span class="go">Char: 101</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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<p class="next">
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Next example: <a href="string-formatting">String Formatting</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/string-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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</body>
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</html>
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