열거형 변형에 따라 매칭하기

match 표현식 만나기

enum Light {
    Red,
    Green,
}

fn action(l: Light) {
    match l {
        Light::Red => println!("Stop"),
        Light::Green => println!("Go"),
    }
}

match 분기의 구조

match light {
    Light::Red => println!("Stop"),
    Light::Green => println!("Go"),
}

완전한 match 프로그램

enum TrafficLight {
    Red,
    Yellow,
    Green,
}

fn main() {
    let light = TrafficLight::Yellow;
    match light {
        TrafficLight::Red => println!("Stop"),
        TrafficLight::Yellow => println!("Slow down"),
        TrafficLight::Green => println!("Go"),
    }
}

match는 모든 경우를 처리해야 합니다

// This would FAIL to compile because
// the Green case is missing:
// match light {
//     Light::Red => println!("Stop"),
// }

_를 사용한 포괄 패턴

enum Coin {
    Penny,
    Nickel,
    Dime,
    Quarter,
}

fn main() {
    let c = Coin::Dime;
    match c {
        Coin::Penny => println!("1 cent"),
        _ => println!("Some other coin"),
    }
}

match는 값을 반환합니다

enum Coin {
    Penny,
    Quarter,
}

fn main() {
    let coin = Coin::Quarter;
    let cents = match coin {
        Coin::Penny => 1,
        Coin::Quarter => 25,
    };
    println!("{} cents", cents);
}

여러 줄로 이루어진 분기 본문

match light {
    Light::Red => {
        println!("Caution!");
        println!("Stop the car");
    }
    Light::Green => println!("Go"),
}

|로 패턴 결합하기

enum Coin {
    Penny,
    Nickel,
    Dime,
    Quarter,
}

fn main() {
    let c = Coin::Nickel;
    match c {
        Coin::Penny | Coin::Nickel => println!("Small coin"),
        _ => println!("Bigger coin"),
    }
}

match와 if/else 비교

비교와 출력 함께 사용하기

enum Direction {
    North,
    South,
    East,
    West,
}

fn main() {
    let d = Direction::West;
    let name = match d {
        Direction::North => "North",
        Direction::South => "South",
        Direction::East => "East",
        Direction::West => "West",
    };
    println!("Heading {}", name);
}

순서가 중요합니다

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