mirror of
https://github.com/sunface/rust-by-practice.git
synced 2025-06-23 20:49:41 +00:00
318 lines
14 KiB
HTML
318 lines
14 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="light sidebar-visible" dir="ltr">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Slice - Rust By Practice</title>
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
<meta name="description" content="Learn Rust with Example, Exercise and real Practice, written with ❤️ by https://course.rs team">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff">
|
|
|
|
<link rel="icon" href="../favicon.svg">
|
|
<link rel="shortcut icon" href="../favicon.png">
|
|
<link rel="stylesheet" href="../css/variables.css">
|
|
<link rel="stylesheet" href="../css/general.css">
|
|
<link rel="stylesheet" href="../css/chrome.css">
|
|
<link rel="stylesheet" href="../css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
|
|
<link rel="stylesheet" href="../fonts/fonts.css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" id="highlight-css" href="../highlight.css">
|
|
<link rel="stylesheet" id="tomorrow-night-css" href="../tomorrow-night.css">
|
|
<link rel="stylesheet" id="ayu-highlight-css" href="../ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
<link rel="stylesheet" href="../theme/style1.css">
|
|
|
|
|
|
<!-- Provide site root and default themes to javascript -->
|
|
<script>
|
|
const path_to_root = "../";
|
|
const default_light_theme = "light";
|
|
const default_dark_theme = "navy";
|
|
</script>
|
|
<!-- Start loading toc.js asap -->
|
|
<script src="../toc.js"></script>
|
|
</head>
|
|
<body>
|
|
<div id="body-container">
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script>
|
|
try {
|
|
let theme = localStorage.getItem('mdbook-theme');
|
|
let sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script>
|
|
const default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? default_dark_theme : default_light_theme;
|
|
let theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
const html = document.documentElement;
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add("js");
|
|
</script>
|
|
|
|
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script>
|
|
let sidebar = null;
|
|
const sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
} else {
|
|
sidebar = 'hidden';
|
|
}
|
|
sidebar_toggle.checked = sidebar === 'visible';
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<!-- populated by js -->
|
|
<mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
|
|
<noscript>
|
|
<iframe class="sidebar-iframe-outer" src="../toc.html"></iframe>
|
|
</noscript>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
|
|
<div class="sidebar-resize-indicator"></div>
|
|
</div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
<div id="menu-bar" class="menu-bar sticky">
|
|
<div class="left-buttons">
|
|
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</label>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="default_theme">Auto</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
</div>
|
|
|
|
<h1 class="menu-title">Rust By Practice</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="../print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
<a href="https://github.com/sunface/rust-by-practice" title="Git repository" aria-label="Git repository">
|
|
<i id="git-repository-button" class="fa fa-github"></i>
|
|
</a>
|
|
<a href="https://github.com/sunface/rust-by-practice/edit/master/en/src/compound-types/slice.md" title="Suggest an edit" aria-label="Suggest an edit">
|
|
<i id="git-edit-button" class="fa fa-edit"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script>
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1 id="slice"><a class="header" href="#slice">Slice</a></h1>
|
|
<p>Slices are similar to arrays, but their length is not known at compile time, so you can't use slice directly.</p>
|
|
<ol>
|
|
<li>🌟🌟 Here, both <code>[i32]</code> and <code>str</code> are slice types, but directly using it will cause errors. You have to use the reference of the slice instead: <code>&[i32]</code>, <code>&str</code>.</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
// Fix the errors, DON'T add new lines!
|
|
fn main() {
|
|
let arr = [1, 2, 3];
|
|
let s1: [i32] = arr[0..2];
|
|
|
|
let s2: str = "hello, world" as str;
|
|
|
|
println!("Success!");
|
|
}</code></pre></pre>
|
|
<p>A slice reference is a two-word object, for simplicity reasons, from now on we will use slice instead of <code>slice reference</code>. The first word is a pointer to the data, and the second word is the length of the slice. The word size is the same as usize, determined by the processor architecture, e.g. 64 bits on an x86-64. Slices can be used to borrow a section of an array, and have the type signature <code>&[T]</code>.</p>
|
|
<ol start="2">
|
|
<li>🌟🌟🌟</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
fn main() {
|
|
let arr: [char; 3] = ['中', '国', '人'];
|
|
|
|
let slice = &arr[..2];
|
|
|
|
// Modify '8' to make it work
|
|
// TIPS: slice( reference ) IS NOT an array, if it is an array, then `assert!` will be passed: Each of the two chars '中' and '国' occupies 4 bytes, 2 * 4 = 8
|
|
assert!(std::mem::size_of_val(&slice) == 8);
|
|
|
|
println!("Success!");
|
|
}</code></pre></pre>
|
|
<ol start="3">
|
|
<li>🌟🌟</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
fn main() {
|
|
let arr: [i32; 5] = [1, 2, 3, 4, 5];
|
|
// Fill the blanks to make the code work
|
|
let slice: __ = __;
|
|
assert_eq!(slice, &[2, 3, 4]);
|
|
|
|
println!("Success!");
|
|
}</code></pre></pre>
|
|
<h3 id="string-slices"><a class="header" href="#string-slices">String slices</a></h3>
|
|
<ol start="4">
|
|
<li>🌟</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
fn main() {
|
|
let s = String::from("hello");
|
|
|
|
let slice1 = &s[0..2];
|
|
// Fill the blank to make the code work, DON'T USE 0..2 again
|
|
let slice2 = &s[__];
|
|
|
|
assert_eq!(slice1, slice2);
|
|
|
|
println!("Success!");
|
|
}</code></pre></pre>
|
|
<ol start="5">
|
|
<li>🌟</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
fn main() {
|
|
let s = "你好，世界";
|
|
// Modify this line to make the code work
|
|
let slice = &s[0..2];
|
|
|
|
assert!(slice == "你");
|
|
|
|
println!("Success!");
|
|
}</code></pre></pre>
|
|
<ol start="6">
|
|
<li>🌟🌟 <code>&String</code> can be implicitly converted into <code>&str</code>.</li>
|
|
</ol>
|
|
<pre><pre class="playground"><code class="language-rust editable edition2021">
|
|
// Fix errors
|
|
fn main() {
|
|
let mut s = String::from("hello world");
|
|
|
|
// Here, &s is `&String` type, but `first_letter` needs a `&str` type.
|
|
// It works because `&String` can be implicitly converted to `&str. If you want to know more, this is called `Deref coercion`.
|
|
let letter = first_letter(&s);
|
|
|
|
s.clear(); // error!
|
|
|
|
println!("the first letter is: {}", letter);
|
|
}
|
|
fn first_letter(s: &str) -> &str {
|
|
&s[..1]
|
|
}</code></pre></pre>
|
|
<blockquote>
|
|
<p>You can find the solutions <a href="https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/slice.md">here</a>(under the solutions path), but only use it when you need it</p>
|
|
</blockquote>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
<a rel="prev" href="../compound-types/array.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
<a rel="next prefetch" href="../compound-types/tuple.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
<a rel="prev" href="../compound-types/array.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
<a rel="next prefetch" href="../compound-types/tuple.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<script>
|
|
window.playground_copyable = true;
|
|
</script>
|
|
|
|
<script src="../ace.js"></script>
|
|
<script src="../editor.js"></script>
|
|
<script src="../mode-rust.js"></script>
|
|
<script src="../theme-dawn.js"></script>
|
|
<script src="../theme-tomorrow_night.js"></script>
|
|
|
|
<script src="../elasticlunr.min.js"></script>
|
|
<script src="../mark.min.js"></script>
|
|
<script src="../searcher.js"></script>
|
|
|
|
<script src="../clipboard.min.js"></script>
|
|
<script src="../highlight.js"></script>
|
|
<script src="../book.js"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
<script src="../assets/custom3.js"></script>
|
|
<script src="../assets/lang1.js"></script>
|
|
|
|
|
|
</div>
|
|
</body>
|
|
</html>
|