Enums and Pattern Matching

Represent choices and handle them safely with match.

Learning objectives

• Define enums
• Store data inside enum variants
• Use match to handle each case

Enums

An enum defines a type that can be one of several variants. It is useful for states, commands, options, and results.

Enums with Data

Enum variants can also hold data. This makes enums powerful for modeling real application logic.

Pattern Matching

match helps you handle every possible variant in a clear and complete way.

Example code

enum Payment {
    Cash,
    Card(String),
    Online { provider: String, amount: f64 },
}

fn main() {
    let payment = Payment::Card(String::from("Visa"));

    match payment {
        Payment::Cash => println!("Paid by cash"),
        Payment::Card(card_type) => println!("Paid by card: {}", card_type),
        Payment::Online { provider, amount } => {
            println!("Paid online using {}: {}", provider, amount);
        }
    }
}