rust 控制流 匹配模式

match

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

fn value_in_cents(coin: Coin) -> u8 {
    match coin {
        Coin::Penny => 1,
        Coin::Nickel => 5,
        Coin::Dime => 10,
        Coin::Quarter => 25,
    }
}
fn main (){
   let a =  value_in_cents(Coin::Penny)
        
}

if let 简单模式

fn main (){
    let some_u8_value = Some(0u8);
    if let Some(3) = some_u8_value {
        println!("three");
    }
}