How to Use the match Expression with Enums

Use the match keyword to destructure an enum value by listing every variant in separate arms. This ensures exhaustive handling of all possible states defined in your enum.

enum Message {
    Quit,
    Move { x: i32, y: i32 },
    Write(String),
    ChangeColor(u8, u8, u8),
}

fn main() {
    let msg = Message::Quit;

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

The match expression acts like a strict switch statement that forces you to handle every possible option an enum can hold. It prevents your program from crashing by ensuring you have a plan for every scenario, much like a traffic light system that must define what happens for red, yellow, and green. You use it whenever you need to take different actions based on the specific type of data you are holding.