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<h2 id="注释"><a class="header" href="#注释">注释</a></h2>
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<!-- commit 5d22a358fb2380aa3f270d7b6269b67b8e44849e -->
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<p>所有程序员都力求使其代码易于理解，不过有时还需要提供额外的解释。在这种情况下，程序员在源码中留下 <strong>注释</strong>（<em>comments</em>），编译器会忽略它们，不过阅读代码的人可能觉得有用。</p>
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<p>这是一个简单的注释：</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
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</span><span class="boring">fn main() {
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</span>// hello, world
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<span class="boring">}</span></code></pre></pre>
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<p>在 Rust 中，惯用的注释样式是以两个斜杠开始注释，并持续到本行的结尾。对于超过一行的注释，需要在每一行前都加上 <code>//</code>，像这样：</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
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</span><span class="boring">fn main() {
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</span>// So we’re doing something complicated here, long enough that we need
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// multiple lines of comments to do it! Whew! Hopefully, this comment will
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// explain what’s going on.
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<span class="boring">}</span></code></pre></pre>
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<p>注释也可以放在包含代码的行的末尾：</p>
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<p><span class="filename">文件名：src/main.rs</span></p>
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<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
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let lucky_number = 7; // I'm feeling lucky today
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}</code></pre></pre>
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<p>不过你更经常看到的是以这种格式使用它们，也就是位于它所解释的代码行的上面一行：</p>
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<p><span class="filename">文件名：src/main.rs</span></p>
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<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
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// I'm feeling lucky today
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let lucky_number = 7;
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}</code></pre></pre>
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<p>Rust 还有另一种注释，称为文档注释，我们将在 14 章的 <a href="ch14-02-publishing-to-crates-io.html">“将 crate 发布到 Crates.io” </a>部分讨论它。</p>
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