# 枚举和模式匹配
[参考链接](https://kaisery.github.io/trpl-zh-cn/ch06-00-enums.html)

## 枚举的定义

```rust
enum IpAddrKind {
  V4,
  V6,
}
```

#### 枚举值

可以像这样创建 IpAddrKind 两个不同成员的实例：

```rust
enum IpAddrKind {
  // V4,
  // V6,
  // 简化写法
  V4(String),
  V6(String),
  V7(u8, u8, u8, u8)
}

// struct IpAddr {
//   kind: IpAddrKind,
//   address: String,
// }

fn main() {
  // let four = IpAddrKind::V4;
  // let five = IpAddrKind::V6;

  // route(IpAddrKind::V4);
  // route(IpAddrKind::V6);

  // let local = IpAddr {
  //   kind: IpAddrKind::V4,
  //   address: String::from("127.0.0.1"),
  // };

  // let test = IpAddr {
  //   kind: IpAddrKind::V6,
  //   address: String::from("::1"),
  // };

  let home = IpAddrKind::V4(String::from("127.0.0.1"));
  let test: = IpAddrKind::V6(String::from("::1"));
  let test = IpAddrKind::V7(127, 0, 0, 1);
}

fn route(ip: IpAddrKind) {

}
```

## match 控制流结构

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

fn main() {
  let enter_value = value_in_enter(Coin::Dime);
  println!("The value of enter is: {}", enter_value) // The value of enter is: 100
}

fn value_in_enter(coin: Coin) -> i8 {
  match coin {
    // 也可进行多代码执行
    Coin::Quarter => {
      println!("Lucky Quarter");
      2
    },
    Coin::Penny => 5,
    Coin::Nickel => 50,
    Coin::Dime => 100,
  }
}
```

#### 绑定值的模式

```rust
#[derive(Debug)]
enum UsState {
  Alabama,
  Alaska,
}
enum Coin {
  Penny,
  Nickel,
  Dime,
  Quarter(UsState),
}

fn main() {
  let enter_value = value_in_enter(Coin::Dime);
  let enter_value = value_in_enter(Coin::Quarter(UsState::Alabama));
  println!("The value of enter is: {}", enter_value) // The value of enter is: 100
}

fn value_in_enter(coin: Coin) -> i8 {
  match coin {
    Coin::Quarter(state) => {
      println!("The value of state is: {:?} !", state); // The value of state is: Alabama !
      2
    },
    Coin::Penny => 5,
    Coin::Nickel => 50,
    Coin::Dime => 100,
  }
}
```

#### 匹配 Option<T>

[参考链接](https://kaisery.github.io/trpl-zh-cn/ch06-02-match.html#%E5%8C%B9%E9%85%8D-optiont)


[后续的直接查阅官网](https://kaisery.github.io/trpl-zh-cn/ch07-00-managing-growing-projects-with-packages-crates-and-modules.html)

> 代码案例依旧记录