rust-exercises/guessing_game/src/main.rs

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

pub struct Guess {
    value: i32,
}

impl Guess {
    pub fn new(value: i32) -> Guess {
        if value < 1 || value > 100 {
            panic!("Guess value must be between 1 and 100, got {value}.");
        }

        Guess { value }
    }
}

fn main() {
    println!("Guess the number!");
    let secret_number = rand::thread_rng().gen_range(1..=100);
    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: Guess = match guess.trim().parse() {
            Ok(num) => Guess::new(num),
            Err(_) => {
                println!("Please type a number!");
                continue;
            },
        };

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

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[should_panic]
    fn greater_than_100() {
        Guess::new(200);
    }
}