现在我们写了一些函数，是时候学习一下注释了。注释是你帮助其他程序猿理解你的代码的备注。编译器基本上会忽略它们。 Rust有两种需要你了解的注释格式：_行注释_（_line comments_）和_文档注释_（_doc comments_）。 ~~~ // Line comments are anything after '//' and extend to the end of the line. let x = 5; // this is also a line comment. // If you have a long explanation for something, you can put line comments next // to each other. Put a space between the // and your comment so that it's // more readable. ~~~ 另一种注释是文档注释。文档注释使用`///`而不是`//`，并且内建Markdown标记支持： ~~~ /// `hello` is a function that prints a greeting that is personalized based on /// the name given. /// /// # Arguments /// /// * `name` - The name of the person you'd like to greet. /// /// # Example /// /// ```rust /// let name = "Steve"; /// hello(name); // prints "Hello, Steve!" /// ~~~ fn hello(name: &str) { println!("Hello, {}!", name); } ``` 当书写文档注释时，加上参数和返回值部分并提供一些用例将是非常有帮助的。不要担心那个`&str`，我们马上会提到它。 你可以使用[rustdoc](http://kaisery.gitbooks.io/rust-book-chinese/content/content/4.4.Documentation%20%E6%96%87%E6%A1%A3.md)工具来将文档注释生成为HTML文档。