-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathrust-basics.html
281 lines (241 loc) · 14.2 KB
/
rust-basics.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>Rust Basics - Tutorial</title>
<!-- Custom HTML head -->
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<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" href="highlight.css">
<link rel="stylesheet" href="tomorrow-night.css">
<link rel="stylesheet" href="ayu-highlight.css">
<!-- Custom theme stylesheets -->
<link rel="stylesheet" href="visualization.css">
</head>
<body>
<!-- Provide site root to javascript -->
<script type="text/javascript">
var path_to_root = "";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script type="text/javascript">
try {
var theme = localStorage.getItem('mdbook-theme');
var 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 type="text/javascript">
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item expanded "><a href="motivation.html"><strong aria-hidden="true">1.</strong> Motivation</a></li><li class="chapter-item expanded "><a href="rust-basics.html" class="active"><strong aria-hidden="true">2.</strong> Rust Basics</a></li><li class="chapter-item expanded "><a href="ownership.html"><strong aria-hidden="true">3.</strong> Ownership</a></li><li class="chapter-item expanded "><a href="borrowing.html"><strong aria-hidden="true">4.</strong> Borrowing</a></li><li class="chapter-item expanded "><a href="vectors.html"><strong aria-hidden="true">5.</strong> Vectors</a></li><li class="chapter-item expanded "><a href="structs.html"><strong aria-hidden="true">6.</strong> Optional: Structures</a></li><li class="chapter-item expanded "><a href="additional_resources.html"><strong aria-hidden="true">7.</strong> Additional Resources</a></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></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 bordered">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<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="light">Light (default)</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">Tutorial</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>
</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 type="text/javascript">
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="rust-basics"><a class="header" href="#rust-basics">Rust Basics</a></h1>
<h2 id="main-function"><a class="header" href="#main-function">Main Function</a></h2>
<p>In every Rust program, the <code>main</code> function executes first:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
// code here will run first
}
</code></pre></pre>
<h2 id="variables"><a class="header" href="#variables">Variables</a></h2>
<p>In Rust, we use <code>let</code> bindings to introduce variables. Variables are <em>immutable</em>
or <em>mutable</em>.</p>
<h3 id="immutable-variables"><a class="header" href="#immutable-variables">Immutable Variables</a></h3>
<p>By default, variables are <em>immutable</em> in Rust. This means that once a value is
bound to the variable, the binding cannot be changed. We use <code>let</code> bindings to
introduce immutable variables as follows:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let x = 5;
}
</code></pre></pre>
<p>In this example, we introduce a variable <code>x</code> of type <code>i32</code> (a 32-bit signed
integer type) and bind the value <code>5</code> to it. </p>
<p>You cannot assign to an immutable variable. So the following example causes a
compiler error:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let x = 5;
x = 6; // ERROR: cannot assign twice to immutable variable x
}
</code></pre></pre>
<h3 id="mutable-variables"><a class="header" href="#mutable-variables">Mutable Variables</a></h3>
<p>If you want to be able to assign to a variable, it must be marked as <em>mutable</em>
with <code>let mut</code>:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let mut x = 5;
x = 6; //OK
}
</code></pre></pre>
<h2 id="copies"><a class="header" href="#copies">Copies</a></h2>
<p>For simple types like integers, binding and assignment creates a copy.
For example, we can bind the value <code>5</code> to <code>x</code> and then bind <code>y</code> with a copy of <code>x</code>:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let x = 5;
let y = x;
}
</code></pre></pre>
<p>Copying occurs only for simple types like <code>i32</code> and other types that
have been marked as copyable (they implement the <code>Copy</code> trait -- we will not
discuss traits here).
We will discuss how more interesting data
structures that are not copyable behave differently in later sections
of the tutorial.</p>
<h2 id="functions"><a class="header" href="#functions">Functions</a></h2>
<p>Besides <code>main</code>, we can define additional functions. In the following example, we
define a function called <code>plus_one</code> which takes an <code>i32</code> as input and returns an
<code>i32</code> value that is one more than the input:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let six = plus_one(5);
}
fn plus_one(x: i32) -> i32 {
x + 1
}
</code></pre></pre>
<p>Notice how there is no explicit return. In Rust, if the last expression in the
function body does not end in a semicolon, it is the return value. (Rust also
has a <code>return</code> keyword, but we do not use it here.)</p>
<h2 id="printing-to-the-terminal"><a class="header" href="#printing-to-the-terminal">Printing to the Terminal</a></h2>
<p>In Rust, we can print to the terminal using <code>println!</code>:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
println!("Hello, world!")
}
</code></pre></pre>
<p>This code prints <code>Hello, world!</code> to the terminal, followed by a newline
character.</p>
<p>We can also use curly brackets in the input string of <code>println!</code> as a
placeholder for subsequent arguments:</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let x = 1;
let y = 2;
println!("x = {} and y = {}", x, y);
}
</code></pre></pre>
<p>This prints <code>x = 1 and y = 2</code>.</p>
<p>Note that the <code>!</code> at the end of <code>println!</code> indicates that it is a <em>macro</em>, not a
function. It behaves slightly differently from normal functions, but you do not
need to worry about the details here. </p>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="motivation.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" href="ownership.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="motivation.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" href="ownership.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 type="text/javascript">
window.playground_copyable = true;
</script>
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
<script src="book.js" type="text/javascript" charset="utf-8"></script>
<!-- Custom JS scripts -->
<script type="text/javascript" src="helpers.js"></script>
</body>
</html>