222 lines
9.3 KiB
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222 lines
9.3 KiB
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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 в примерах: Парсинг чисел (Number Parsing)</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 = 'random-numbers';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'url-parsing';
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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="number-parsing">
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<h2><a href="./">Go в примерах</a>: Парсинг чисел (Number Parsing)</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Парсинг чисел из строк является распространенной задачей;
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Вот как это реализовать в Go.</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/4PKUrIjNyTE" target="_blank"><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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<p>Для решения этой задачи подойдет встроенный пакет
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<code>strconv</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="kn">import</span> <span class="p">(</span>
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<span class="s">"fmt"</span>
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<span class="s">"strconv"</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>С помощью <code>ParseFloat</code>, параметр <code>64</code> говорит о том,
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сколько битов точности необходимо использовать.</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">f</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseFloat</span><span class="p">(</span><span class="s">"1.234"</span><span class="p">,</span> <span class="mi">64</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="nx">f</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>Для <code>ParseInt</code> 0 означает вывод базы из строки. <code>64</code>
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необходимо, чтобы результат соответствовал 64 битам.</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">i</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseInt</span><span class="p">(</span><span class="s">"123"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</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="nx">i</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><code>ParseInt</code> будет распознавать числа в шестнадцатеричной
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системе.</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">d</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseInt</span><span class="p">(</span><span class="s">"0x1c8"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</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="nx">d</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><code>ParseUint</code> так же доступен.</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">u</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseUint</span><span class="p">(</span><span class="s">"789"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</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="nx">u</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><code>Atoi</code> это удобная функция для парсинга в десятеричный
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<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="nx">k</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">Atoi</span><span class="p">(</span><span class="s">"135"</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="nx">k</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>Функции парсинга возвращают ошибку в случае некорректных
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аргументов.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">Atoi</span><span class="p">(</span><span class="s">"wat"</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="nx">e</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 number-parsing.go
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<span class="go">1.234</span>
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<span class="go">123</span>
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<span class="go">456</span>
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<span class="go">789</span>
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<span class="go">135</span>
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<span class="go">strconv.ParseInt: parsing "wat": invalid syntax</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>Далее мы рассмотрим парсинг URL.</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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Следующий пример: <a href="url-parsing">Парсинг URL (URL Parsing)</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/number-parsing">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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</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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