Rustで数当てコンソールアプリ

Dockerで開発環境

Dockerfile

FROM rust:1.32
RUN cargo install wasm-pack && cargo install cargo-generate

run

docker run -it --rm -p 8080:8080 -e USER=$USER -v "$PWD":/usr/src/ -w /usr/src eg-rust /bin/bash

パッケージ生成

cargo new guessing_game
cd guessing_game

こんな感じのファイルが生成されます。

ソース書き換え

main.rs

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

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

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

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

    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;
            }
        }
    }
}

Cargo.toml

dependenciesにrandを追加

....省略

[dependencies]
rand = "0.3.14"

動作確認

cargo run

こんな感じで、数当て

Guess the number!
The secret number is: 72
Please input your guess.
12
You guessed: 12
Too small!
Please input your guess.
34
You guessed: 34
Too small!
Please input your guess.
72
You guessed: 72
You win!