编写猜数字游戏

https://rustwiki.org/zh-CN/book/ch02-00-guessing-game-tutorial.html

我们会实现一个经典的新手编程问题：猜数字游戏。这是它的工作原理：程序会随机生成一个 1 到 100 之间的整数。接着它会提示玩家猜一个数并输入，然后指出猜测是大了还是小了。如果猜对了，它会打印祝贺信息并退出。

Cargo.toml

[package]
name = "guessing_game"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rand = "0.8.3"

main.rs

use rand::Rng;
use std::cmp::Ordering;
use std::io;

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

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

    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;
            }
        }
    }
}

---

语法比较，引入包/命名空间：

• rust：use rand::Rng;

• C++：#inlude <stdlib>，又有点像命名空间using namespace std;

• python：from math import radians

语法比较，io 后的 expect

Rust

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

Swift

guard let guess = readLine() else {
    print("Failed to read line")
    return ""
}

语法比较，引用

Rust

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

C++

#include <iostream>

void modifyValue(int &value)
{
    // 通过指针修改原始变量的值
    value = 24; // 修改传入的变量值
}

int main()
{
    int number = 42;
    std::cout << "原始值: " << number << std::endl; // 原始值: 42

    modifyValue(number);

    std::cout << "修改后的值: " << number << std::endl; // 修改后的值: 24

    return 0;
}

语法比较，result 和 error

Rust

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

JavaScript

contract.methods.addEventApprove(index,approve,identity).send({from:account})
.then(function(res){
    console.log("To do list reply Request Send",res);
}, function(error){
    console.log("To do list reply Failed!",error);
});