Rust Foo

Guessing Game

On chapter 2 of the book 'The Rust Programming Language (2nd Edition)', specifically titled 'Programming a guessing game' it has me setting up a new cargo project similar to before as follows:

cargo new guessing_game
cd guessing_game

It has then set up the following files:

• src/main.rs the main code file of the project:

fn main() {
    println!("Hello, world!");
}

Seem to contain a basic hello world program as a starting point.

Then we have:

Cargo.toml

[package]
name = "guessing_game"
version = "0.1.0"
edition = "2024"

[dependencies]

Everything is self explanatory there.

In the overall code for this chapter I have the following, changing the file main.rs mentioned above:

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

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

    let secret_number = rand::rng().random_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: 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;
            }
        }
    }
}

What I learned in this chapter

• Brought in an external crate (rand) to generate a secret number.
• Used io::stdin().read_line(&mut guess) to get and store user input.
• Converted the input string into a number with trim().parse() and a match to skip bad input.
• Employed a loop plus match guess.cmp(&secret_number) for the guessing logic.
• Reinforced ownership and borrowing by passing &mut guess and &secret_number.
• Printed messages with println! and Rust’s formatting placeholders.