How do I read a single String from standard input?

问题:

There isn't straightforward instruction on receiving a string as a variable in the std::io documentation, but I figured this should work:

use std::io;
let line = io::stdin().lock().lines().unwrap();

But I'm getting this error:

src\main.rs:28:14: 28:23 error: unresolved name `io::stdin`
src\main.rs:28          let line = io::stdin.lock().lines().unwrap();
                                   ^~~~~~~~~

Why?

I'm using a nightly Rust v1.0.

回答1:

Here's the code you need to do what you are trying (no comments on if it is a good way to go about it:

use std::io::{self, BufRead};

fn main() {
    let stdin = io::stdin();
    let line = stdin.lock()
        .lines()
        .next()
        .expect("there was no next line")
        .expect("the line could not be read");
}

If you want more control over where the line is read to, you can use Stdin::read_line. This accepts a &mut String to append to. With this, you can ensure that the string has a large enough buffer, or append to an existing string:

use std::io::{self, BufRead};

fn main() {
    let mut line = String::new();
    let stdin = io::stdin();
    stdin.lock().read_line(&mut line).expect("Could not read line");
    println!("{}", line)
}