main.rs

use std::old_io;
use std::rand;
use std::cmp::Ordering;

fn main() {
    println!("Guess the number!");

    let secret_number = (rand::random::<u32>() % 100) +1; //secret_number: i32

    println!("Please input your guess.");

    loop {
        let input = old_io::stdin().read_line()
            .ok()
            .expect("Failed to read line");

        let input_num: Result<u32, _> = input.trim().parse();

        let num = match input_num {
            Ok(num) => num,
            Err(_) => {
                println!("Please input a number!");
                continue;
            }
        };

        println!("You guessed: {:?}", num);

        match cmp(num, secret_number) {
            Ordering::Less => println!("Too small!"),
            Ordering::Greater => println!("Too big!"),
            Ordering::Equal => {
                println!("You win!");
                return;
            },
        }
    }
}

fn cmp(a: u32, b: u32) -> Ordering {
    if a < b { Ordering::Less }
    else if a > b { Ordering::Greater }
    else { Ordering::Equal }
}