Rust——控制流-循环-loop-while-for

Rust 有三种循环：loop、while 和 for

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

    // 使用 loop 重复执行代码
    // loop {
    //     println!("again!");
    // }

    // let mut counter = 0;

    // let result = loop {
    //     counter += 1;

    //     if counter == 10 {
    //         break counter * 2;
    //     }
    // };

    // println!("The result is {result}");

    let mut count = 0;
    // 标签 counting_up
    'counting_up: loop {
        println!("count = {count}");
        let mut remaining = 10;

        loop {
            println!("remaining = {remaining}");
            if remaining == 9 {
                // 没有指定标签的 break 将只退出内层循环
                break;
            }
            if count == 2 {
                // break 'counting_up; 语句将退出外层循环
                break 'counting_up;
            }
            remaining -= 1;
        }

        count += 1;
    }
    println!("End count = {count}");

    let mut number = 3;

    while number != 0 {
        println!("{number}!");

        number -= 1;
    }

    println!("LIFTOFF!!!");

    let a = [10, 20, 30, 40, 50];
    let mut index = 0;

    while index < 5 {
        println!("the value is: {}", a[index]);

        index += 1;
    }

    let a = [10, 20, 30, 40, 50];

    for element in a {
        println!("the value is: {}", element);
    }

    // Range 标准库提供的类型，用来生成从一个数字开始到另一个数字之前结束的所有数字的序列 rev 用来反转
    for number in (1..4).rev() {
        println!("the value is: {}", number);
    }
    println!("LIFTOFF!!!");
}