245 lines
9.7 KiB
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Generated
245 lines
9.7 KiB
Plaintext
Generated
<!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: Base64 Encoding</title>
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<div class="example" id="base64-encoding">
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<h2><a href="./">Go by Example</a>: Base64 Encoding</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Go provides built-in support for <a href="https://en.wikipedia.org/wiki/Base64">base64
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encoding/decoding</a>.</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="https://go.dev/play/p/yztzkirFEvv"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
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</pre>
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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>This syntax imports the <code>encoding/base64</code> package with
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the <code>b64</code> name instead of the default <code>base64</code>. It’ll
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save us some space below.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="kn">import</span> <span class="p">(</span>
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<span class="nx">b64</span> <span class="s">"encoding/base64"</span>
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<span class="s">"fmt"</span>
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<span class="p">)</span>
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</pre>
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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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<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
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</pre>
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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 the <code>string</code> we’ll encode/decode.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nx">data</span> <span class="o">:=</span> <span class="s">"abc123!?$*&()'-=@~"</span>
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</pre>
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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 supports both standard and URL-compatible
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base64. Here’s how to encode using the standard
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encoder. The encoder requires a <code>[]byte</code> so we
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convert our <code>string</code> to that type.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nx">sEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nf">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">sEnc</span><span class="p">)</span>
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</pre>
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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>Decoding may return an error, which you can check
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if you don’t already know the input to be
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well-formed.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="nx">sDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nf">DecodeString</span><span class="p">(</span><span class="nx">sEnc</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">sDec</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">()</span>
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</pre>
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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>This encodes/decodes using a URL-compatible base64
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format.</p>
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</td>
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<td class="code">
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<pre class="chroma">
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<span class="nx">uEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nf">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
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<span class="nx">uDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nf">DecodeString</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">uDec</span><span class="p">))</span>
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<span class="p">}</span>
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</pre>
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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>The string encodes to slightly different values with the
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standard and URL base64 encoders (trailing <code>+</code> vs <code>-</code>)
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but they both decode to the original string as desired.</p>
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</td>
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<td class="code leading">
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<pre class="chroma">
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<span class="gp">$</span> go run base64-encoding.go
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<span class="go">YWJjMTIzIT8kKiYoKSctPUB+
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</span><span class="go">abc123!?$*&()'-=@~</span></pre>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code">
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<pre class="chroma"><span class="go">YWJjMTIzIT8kKiYoKSctPUB-
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</span><span class="go">abc123!?$*&()'-=@~</span></pre>
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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="reading-files">Reading Files</a>.
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> | <button id="theme-button">Toggle theme</button>
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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 (\u000A b64 \"encoding/base64\"\u000A \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' data :\u003D \"abc123!?$*\u0026()\'-\u003D@~\"\u000A');codeLines.push(' sEnc :\u003D b64.StdEncoding.EncodeToString([]byte(data))\u000A fmt.Println(sEnc)\u000A');codeLines.push(' sDec, _ :\u003D b64.StdEncoding.DecodeString(sEnc)\u000A fmt.Println(string(sDec))\u000A fmt.Println()\u000A');codeLines.push(' uEnc :\u003D b64.URLEncoding.EncodeToString([]byte(data))\u000A fmt.Println(uEnc)\u000A uDec, _ :\u003D b64.URLEncoding.DecodeString(uEnc)\u000A fmt.Println(string(uDec))\u000A}\u000A');codeLines.push('');codeLines.push('');
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