1.Rust Guess the number

use std::io;
use rand::Rng;
use std::cmp::Ordering; //库
fn main() {//循环
    println!("Guess the number!");
    let secret_number = rand::thread_rng().gen_range(1..101);//生成随机数字
    loop {
        println!("Please input your guess.");
        let mut guess = String::new(); // 声明可变量
        //标准库引用  读取一行
        io::stdin().
            read_line(&mut guess).
            expect("Failed to read line ");//expect 会导致程序崩溃，并显示当做参数传递给 expect 的信息。
        let guess: u32 = guess.trim().parse().expect("Please type a number!");
        println!("You guessed: {}", guess);
        match guess.cmp(&secret_number) { // match 分支比较
            Ordering::Less => println!("Too small!"),
            Ordering::Greater => println!("Too big!"),
            Ordering::Equal => {
                println!("You win!");
                break;
            }
        }
    }
}