yeray/gobyexample
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
gobyexample/public/slices
badkaktus 94b86c03fd link to my project
2019-10-15 15:02:01 +03:00

324 lines
17 KiB
Plaintext
Generated
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go в примерах: Срезы (Slices)</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'arrays';
}
if (e.key == "ArrowRight") {
window.location.href = 'maps';
}
}
</script>
<body>
<div class="example" id="slices">
<h2><a href="./">Go в примерах</a>: Срезы (Slices)</h2>
<table>
<tr>
<td class="docs">
<p><em>Срезы</em> являются ключевым типом данных в Go,
предоставляя более мощный интерфейс для последовательностей,
чем массивы.</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="http://play.golang.org/p/32lRsL-MYrP" target="_blank"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>В отличии от массивов, длина среза зависит от содержащихся
в срезе элементов, а не определена при инициализации.
Создать пустой срез в ненулевой длиной можно используя
оператор <code>make</code>. В этом пример мы создаем слайс строк
длиной 3 (заполненный нулевыми значениями).</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;emp:&quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Мы можем устанавливать и получать значения, как в массивах.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">s</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="p">=</span> <span class="s">&quot;a&quot;</span>
<span class="nx">s</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="p">=</span> <span class="s">&quot;b&quot;</span>
<span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span> <span class="p">=</span> <span class="s">&quot;c&quot;</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;set:&quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;get:&quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">])</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p><code>len</code> возвращает длину среза, как и ожидалось.</p>
</td>
<td class="code leading">
<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">&quot;len:&quot;</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>В дополнение к базовой функциональности, срезы
имеют несколько дополнительных особенностей
по сравнению с массивыми. Одна из них - <code>append</code>,
которая возвращает срезу содержащий одно или более
новых значений. Обратите внимание, что результат
функции <code>append</code> необходимо присвоить в переменную,
т.к. это уже будет новый срез.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">&quot;d&quot;</span><span class="p">)</span>
<span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">&quot;e&quot;</span><span class="p">,</span> <span class="s">&quot;f&quot;</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;apd:&quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Срезы могут быть скопированы с помощью <code>copy</code>. В
данном примере мы создаем пустой срез <code>c</code> такой же
длины как и <code>s</code> и копируем данные из <code>s</code> в <code>c</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">c</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
<span class="nb">copy</span><span class="p">(</span><span class="nx">c</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;cpy:&quot;</span><span class="p">,</span> <span class="nx">c</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Срезы поддерживают оператор <code>slice</code> (синтаксис
использование <code>slice[low:high]</code>). Для примера,
тут мы получаем срез состоящий из элементов
<code>s[2]</code>, <code>s[3]</code>, и <code>s[4]</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">l</span> <span class="o">:=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:</span><span class="mi">5</span><span class="p">]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;sl1:&quot;</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Тут мы получаем срез до элемента <code>s[5]</code> (исключая его).</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[:</span><span class="mi">5</span><span class="p">]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;sl2:&quot;</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>А тут получаем срез от <code>s[2]</code> (включая его) и до конца
исходного среза.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;sl3:&quot;</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Мы можем объявить и заполнить срез значениями в одну
строку.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">t</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">&quot;g&quot;</span><span class="p">,</span> <span class="s">&quot;h&quot;</span><span class="p">,</span> <span class="s">&quot;i&quot;</span><span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;dcl:&quot;</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Срезы можно объединять в многомерные структуры
данных. Длина внутренних срезов может варьироваться,
в отличии от многомерных массивов.</p>
</td>
<td class="code">
<div class="highlight"><pre> <span class="nx">twoD</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([][]</span><span class="kt">int</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
<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">&lt;</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">innerLen</span> <span class="o">:=</span> <span class="nx">i</span> <span class="o">+</span> <span class="mi">1</span>
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">]</span> <span class="p">=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">int</span><span class="p">,</span> <span class="nx">innerLen</span><span class="p">)</span>
<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">&lt;</span> <span class="nx">innerLen</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
<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>
<span class="p">}</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;2d: &quot;</span><span class="p">,</span> <span class="nx">twoD</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>Обратите внимание, несмотря на то что срезы
являются отдельным типом данных, отображаются
они так же как массивы командой <code>fmt.Println</code>.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="gp">$</span> go run slices.go
<span class="go">emp: [ ]</span>
<span class="go">set: [a b c]</span>
<span class="go">get: c</span>
<span class="go">len: 3</span>
<span class="go">apd: [a b c d e f]</span>
<span class="go">cpy: [a b c d e f]</span>
<span class="go">sl1: [c d e]</span>
<span class="go">sl2: [a b c d e]</span>
<span class="go">sl3: [c d e f]</span>
<span class="go">dcl: [g h i]</span>
<span class="go">2d: [[0] [1 2] [2 3 4]]</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Посмотрите этот <a href="http://blog.golang.org/2011/01/go-slices-usage-and-internals.html">отличный пост</a>,
написаный командой Go, чтобы узнать больше о разработке
и использовании срезов в Go.</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
<p>Теперь, когда мы рассмотрели массивы и срезы, мы
посмотрим другую ключевую встроенную структуру
данных Go: карты.</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
Следующий пример: <a href="maps">Карты (Maps)</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/slices">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
<br/>
переведено Nick S. | <a href="https://github.com/badkaktus/gobyexample">исходники</a>
</p>
</div>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func main() {\u000A');codeLines.push(' s := make([]string, 3)\u000A fmt.Println(\"emp:\", s)\u000A');codeLines.push(' s[0] = \"a\"\u000A s[1] = \"b\"\u000A s[2] = \"c\"\u000A fmt.Println(\"set:\", s)\u000A fmt.Println(\"get:\", s[2])\u000A');codeLines.push(' fmt.Println(\"len:\", len(s))\u000A');codeLines.push(' s = append(s, \"d\")\u000A s = append(s, \"e\", \"f\")\u000A fmt.Println(\"apd:\", s)\u000A');codeLines.push(' c := make([]string, len(s))\u000A copy(c, s)\u000A fmt.Println(\"cpy:\", c)\u000A');codeLines.push(' l := s[2:5]\u000A fmt.Println(\"sl1:\", l)\u000A');codeLines.push(' l = s[:5]\u000A fmt.Println(\"sl2:\", l)\u000A');codeLines.push(' l = s[2:]\u000A fmt.Println(\"sl3:\", l)\u000A');codeLines.push(' t := []string{\"g\", \"h\", \"i\"}\u000A fmt.Println(\"dcl:\", t)\u000A');codeLines.push(' twoD := make([][]int, 3)\u000A for i := 0; i \x3C 3; i++ {\u000A innerLen := i + 1\u000A twoD[i] = make([]int, innerLen)\u000A for j := 0; j \x3C innerLen; j++ {\u000A twoD[i][j] = i + j\u000A }\u000A }\u000A fmt.Println(\"2d: \", twoD)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
</script>
<script src="site.js" async></script>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink