课后5.md

函数

1. 🌟🌟🌟

fn main() {
    // 不要修改下面两行代码!
    let (x, y) = (1, 2);
    let s = sum(x, y);

    assert_eq!(s, 3);
}

fn sum(x: i32, y: i32) -> i32{
    x + y
}

2. 🌟🌟

fn main() {
   print();
}

// 使用另一个类型来替代 i32
fn print() -> () {
   println!("hello,world");
}

3. 🌟🌟🌟

fn main() {
    never_return();
}

use std::thread;
use std::time;

fn never_return() -> ! {
    // implement this function, don't modify fn signatures
    loop {
        println!("I return nothing");
        // sleeping for 1 second to avoid exhausting the cpu resource
        thread::sleep(time::Duration::from_secs(1))
    }
}

fn never_return() -> ! {
    // 实现这个函数，不要修改函数签名!
    panic!("I loop forever");
}

4. 🌟🌟

// IMPLEMENT this function in THREE ways
fn never_return_fn() -> ! {
    panic!("I loop forever");
}

// IMPLEMENT this function in THREE ways
fn never_return_fn() -> ! {
    todo!();
}

// IMPLEMENT this function in THREE ways
fn never_return_fn() -> ! {
    loop {
        std::thread::sleep(std::time::Duration::from_secs(1))
    }
}

5. 🌟🌟

fn main() {
    // 填空
    let b = false;

    let _v = match b {
        true => 1,
        // 发散函数也可以用于 `match` 表达式，用于替代任何类型的值
        false => {
            println!("Success!");
            panic!("we have no value for `false`, but we can panic")
        }
    };

    println!("Exercise Failed if printing out this line!");
}