让我们看看你的错误信息:

Let's look at your error message:

error[E0599]: no method named `read_to_string` found for type `std::result::Result<std::fs::File, std::io::Error>` in the current scope
  --> src/main.rs:11:14
   |
11 |         file.read_to_string(&mut s);
   |              ^^^^^^^^^^^^^^ method not found in `std::result::Result<std::fs::File, std::io::Error>`

错误消息几乎就是它在罐头上所说的 - 类型 Result 确实没有方法read_to_string.这实际上是 一个关于 trait Read的方法代码>.

The error message is pretty much what it says on the tin - the type Result does not have the method read_to_string. That's actually a method on the trait Read.

你有一个 Result 因为 File::open(&path) 可以失败.失败用 Result 类型表示.Result 可以是 Ok，这是成功案例，或者是 Err，失败案例.

You have a Result because File::open(&path) can fail. Failure is represented with the Result type. A Result may be either an Ok, which is the success case, or an Err, the failure case.

您需要以某种方式处理失败情况.最简单的方法是使用 expect:

You need to handle the failure case somehow. The easiest is to just die on failure, using expect:

let mut file = File::open(&path).expect("Unable to open");

您还需要将 Read 带入范围才能访问 read_to_string:

You'll also need to bring Read into scope to have access to read_to_string:

use std::io::Read;

我强烈推荐通读Rust 编程语言 并执行示例.带有Result的可恢复错误一章代码> 将是高度相关的.我认为这些文档是一流的！

I'd highly recommend reading through The Rust Programming Language and working the examples. The chapter Recoverable Errors with Result will be highly relevant. I think these docs are top-notch!