trim user input

user_input.rs

use std::io;

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

    let trim_input = user_input.trim();
    match trim_input.parse::<u32>() {
        Ok(i) => println!("user input is integer : {}", i),
        Err(..) => println!("user input is not an integer: {}", trim_input)
    };
}