将字符串与从输入读取的字符串进行比较在Rust中不匹配 [英] Comparing a string against a string read from input does not match in Rust

问题描述

在下面的代码中，我希望在用户输入q时打印哇消息，但事实并非如此。

In the following code, I was expecting the message "wow" to be printed when the user enters "q", but it does not.

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input)
        .expect("failed to read line");

    if input == "q" {
       println!("wow") ;
    }
}

为什么邮件没有按预期打印？

Why is the message not printed as expected?

推荐答案

您的输入字符串包含一个尾随换行符。使用 trim 将其删除：

Your input string contains a trailing newline. Use trim to remove it:

use std::io;

fn main() {
    let mut input = String::new();
    io::stdin()
        .read_line(&mut input)
        .expect("failed to read line");

    if input.trim() == "q" {
        println!("wow") ;
    }
}

您可以通过打印价值来自己看到输入

You could see this yourself by printing the value of the input

println!("{:?}", input);

$ ./foo
q
"q\n"

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