struct User {
    username: String,
    email: String,
    active: bool,
}

fn main() {
    let user = User {
        username: String::from("john"),
        email: String::from("[email protected]"),
        active: true,
    };
    
    println!("User: {}", user.username);
}

struct Rectangle {
    width: u32,
    height: u32,
}

impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
    
    fn new(width: u32, height: u32) -> Rectangle {
        Rectangle { width, height }
    }
}

enum Message {
    Quit,
    Move { x: i32, y: i32 },
    Write(String),
    ChangeColor(i32, i32, i32),
}

fn process(msg: Message) {
    match msg {
        Message::Quit => println!("Quit"),
        Message::Move { x, y } => println!("Move to {}, {}", x, y),
        Message::Write(text) => println!("Text: {}", text),
        Message::ChangeColor(r, g, b) => println!("RGB: {}, {}, {}", r, g, b),
    }
}

fn divide(a: f64, b: f64) -> Option<f64> {
    if b == 0.0 {
        None
    } else {
        Some(a / b)
    }
}