How to trim off Newline and Carriage-return from a line read from stdin in Rust?

Question

I want to read a line from stdin and store it in a string variable and parse the string value into a u32 integer value. The read_line() method reads 2 extra UTF-8 values which cause the parse method to panic.

Below is what I have tried to trim off Carriage-return and Newline:

use std::io;
use std::str;

fn main() {
    let mut input = String::new();
    match io::stdin().read_line(&mut input) {
        Ok(n) => {
            println!("{:?}", input.as_bytes());
            println!("{}", str::from_utf8(&input.as_bytes()[0..n-2]).unwrap());
        }
        Err(e) => {
            println!("{:?}", e);
        }
    }
}

What is the most idiomatic way to do this in Rust?

You can also use the `lines()` iterator, which will trim the newline characters for you. — Sven Marnach, May 22 '19 at 21:13
@SvenMarnach why not make an answer with this? It was the first result on google for me as a new rust learner — ch4rl1e97, Apr 13 '23 at 23:45

score 6 · Accepted Answer · edited May 22 '19 at 23:11

String has a trim method that returns a trimmed string slice:

use std::io;
use std::str;

fn main() {
    let mut input = String::new();
    match io::stdin().read_line(&mut input) {
        Ok(_) => {
            let trimmed_input = input.trim();
            println!("{:?}", trimmed_input.as_bytes());
            println!("{}", trimmed_input);
        }
        Err(e) => {
            println!("{:?}", e);
        }
    }
}

Result for "test" input:

[116, 101, 115, 116]
test

How to trim off Newline and Carriage-return from a line read from stdin in Rust?

1 Answers1

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