How to read an integer input from the user in Rust 1.0?

Question

Existing answers I\'ve found are all based on from_str (such as Reading in user input from console once efficiently), but apparently from_str(x) h

Answer 1

Here are a few possibilities (Rust 1.7):

use std::io;

fn main() {
    let mut n = String::new();
    io::stdin()
        .read_line(&mut n)
        .expect("failed to read input.");
    let n: i32 = n.trim().parse().expect("invalid input");
    println!("{:?}", n);

    let mut n = String::new();
    io::stdin()
        .read_line(&mut n)
        .expect("failed to read input.");
    let n = n.trim().parse::().expect("invalid input");
    println!("{:?}", n);

    let mut n = String::new();
    io::stdin()
        .read_line(&mut n)
        .expect("failed to read input.");
    if let Ok(n) = n.trim().parse::() {
        println!("{:?}", n);
    }
}

These spare you the ceremony of pattern matching without depending on extra libraries.