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<h1 class="menu-title">Rust语言圣经(Rust Course)</h1>
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<main>
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<h1 id="rust-基本概念"><a class="header" href="#rust-基本概念">Rust 基本概念</a></h1>
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<p>从现在开始，我们正式踏入了 Rust 大陆，这片广袤而神秘的世界，在这个世界中，将接触到很多之前都没有听过的概念：</p>
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<ul>
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<li>所有权、借用、生命周期</li>
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<li>宏编程</li>
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<li>模式匹配</li>
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</ul>
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<p>类似的还有很多，不过不用怕，引用武林外传一句话：咱上面有人。有本书在，一切虚妄终将烟消云散。</p>
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<p>本章主要介绍 Rust 的基础语法、数据类型、项目结构等，学完本章，你将对 Rust 代码有一个清晰、完整的认识。</p>
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<p>开始之前先通过一段代码来简单浏览下 Rust 的语法：</p>
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<pre><pre class="playground"><code class="language-rust edition2021">// Rust 程序入口函数，跟其它语言一样，都是 main，该函数目前无返回值
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fn main() {
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// 使用let来声明变量，进行绑定，a是不可变的
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// 此处没有指定a的类型，编译器会默认根据a的值为a推断类型：i32，有符号32位整数
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// 语句的末尾必须以分号结尾
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let a = 10;
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// 主动指定b的类型为i32
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let b: i32 = 20;
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// 这里有两点值得注意：
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// 1. 可以在数值中带上类型:30i32表示数值是30，类型是i32
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// 2. c是可变的，mut是mutable的缩写
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let mut c = 30i32;
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// 还能在数值和类型中间添加一个下划线，让可读性更好
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let d = 30_i32;
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// 跟其它语言一样，可以使用一个函数的返回值来作为另一个函数的参数
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let e = add(add(a, b), add(c, d));
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// println!是宏调用，看起来像是函数但是它返回的是宏定义的代码块
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// 该函数将指定的格式化字符串输出到标准输出中(控制台)
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// {}是占位符，在具体执行过程中，会把e的值代入进来
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println!("( a + b ) + ( c + d ) = {}", e);
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}
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// 定义一个函数，输入两个i32类型的32位有符号整数，返回它们的和
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fn add(i: i32, j: i32) -> i32 {
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// 返回相加值，这里可以省略return
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i + j
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}</code></pre></pre>
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<blockquote>
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<p>注意
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在上面的 <code>add</code> 函数中，不要为 <code>i+j</code> 添加 <code>;</code>，这会改变语法导致函数返回 <code>()</code> 而不是 <code>i32</code>，具体参见<a href="https://course.rs/basic/base-type/statement-expression.html">语句和表达式</a>。</p>
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</blockquote>
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<p>有几点可以留意下：</p>
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<ul>
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<li>字符串使用双引号 <code>""</code> 而不是单引号 <code>''</code>，Rust 中单引号是留给单个字符类型（<code>char</code>）使用的</li>
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<li>Rust 使用 <code>{}</code> 来作为格式化输出占位符，其它语言可能使用的是 <code>%s</code>，<code>%d</code>，<code>%p</code> 等，由于 <code>println!</code> 会自动推导出具体的类型，因此无需手动指定</li>
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