Rust-lang(hello world 续)

loop

上面的例子只能猜测一次，然后程序就停掉了，现在我们想不停的重复猜测，这里就用到循环了,当我们猜测正确的时候停止循环！

fn main() {
    println!("Hello, world!");

    let secret_number = rand::thread_rng().gen_range(1,101);

    println!("Please gusses secret number  !");

    loop {
        let mut number = String::new();

        io::stdin().read_line(&mut number).expect("Failed to read_line");

        let number : u32 = number.trim().parse().expect("Please type a number");

        println!("Hello,your number is {}", number);

        println!("The secret number is: {}", secret_number);

        match number.cmp(&secret_number) {
           Ordering::Less => println!("too small!"),
           Ordering::Greater => println!("too big!"),
           Ordering::Equal => {
            println!("You win!");
            break;
           }
        }
    }

}

问题，又来了，当我们不小心输入错误，程序panic了，但是我们想重新输入，怎么办？

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

    let secret_number = rand::thread_rng().gen_range(1, 101);

    println!("The secret number is: {}", secret_number);

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

        let mut guess = String::new();

        io::stdin().read_line(&mut guess)
            .expect("failed to read line");

        let guess: u32 = match guess.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        };

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

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