Rust编程(四）猜数字游戏

创建新项目

如下命令创建新项目

$ cargo new guessing_game
$ cd guessing_game

试运行查看是否创建成功

$ cargo run
   Compiling guessing_game v0.1.0 (file:///projects/guessing_game)
    Finished dev [unoptimized + debuginfo] target(s) in 1.50s
     Running `target/debug/guessing_game`
Hello, world!

猜数字处理

src/main.rs

use std::io;

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

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

    let mut guess = String::new();

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

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

use std::io;

use std::io；表示包引用

let mut guess = String::new();

创建可变字符串

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

标准输入读取一行，expect（）部分处理可能的错误

产生随机数字

Cargo.toml 添加对rand包的引用

[dependencies]

rand = "0.8.3"

Shell中运行以下命令

$ cargo build
    Updating crates.io index
  Downloaded rand v0.8.3
  Downloaded libc v0.2.86
  Downloaded getrandom v0.2.2
  Downloaded cfg-if v1.0.0
  Downloaded ppv-lite86 v0.2.10
  Downloaded rand_chacha v0.3.0
  Downloaded rand_core v0.6.2
   Compiling rand_core v0.6.2
   Compiling libc v0.2.86
   Compiling getrandom v0.2.2
   Compiling cfg-if v1.0.0
   Compiling ppv-lite86 v0.2.10
   Compiling rand_chacha v0.3.0
   Compiling rand v0.8.3
   Compiling guessing_game v0.1.0 (file:///projects/guessing_game)
    Finished dev [unoptimized + debuginfo] target(s) in 2.53s

将会显示下载依赖包并进行编译

$ cargo update
    Updating crates.io index
    Updating rand v0.8.3 -> v0.8.4

更新依赖包版本

代码修改

use std::io;
use rand::Rng;

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

    let secret_number = rand::thread_rng().gen_range(1..=100);

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

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

    let mut guess = String::new();

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

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

编译运行

$ cargo run
   Compiling guessing_game v0.1.0 (file:///projects/guessing_game)
    Finished dev [unoptimized + debuginfo] target(s) in 2.53s
     Running `target/debug/guessing_game`
Guess the number!
The secret number is: 7
Please input your guess.
4
You guessed: 4

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/guessing_game`
Guess the number!
The secret number is: 83
Please input your guess.
5
You guessed: 5

比较数字

use std::{io, cmp::Ordering};

use rand::Rng;

fn main() {
    println!("Hello, world!");
    println!("猜数");
    let secret_number = rand::thread_rng().gen_range(1..=100);

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

    loop {
        let mut guess = String::new();
        io::stdin().read_line(&mut guess).expect("无法读取行");
        println!("你猜的是：{}",guess);

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

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

运行

$ cargo run
   Compiling guessing_game v0.1.0 (file:///projects/guessing_game)
    Finished dev [unoptimized + debuginfo] target(s) in 0.43s
     Running `target/debug/guessing_game`
Guess the number!
The secret number is: 58
Please input your guess.
  76
You guessed: 76
Too big!