Rust的模式匹配

match匹配

match可以结合枚举使用，例如

enum IpVersion {V4,V6,
}fn ParseIpVersion(version: IpVersion) -> String {match version {IpVersion::V4 => String::from("ipv4"),IpVersion::V6 => String::from("ipv6"),}
}

match结合绑定值的枚举，例如

enum Ip {V4(String),V6(String),
}fn ParseIpVersion(ip: Ip) {match ip {Ip::V4(ipv4) => println!("ipv4: {}", ipv4),Ip::V6(ipv6) => println!("ipv6: {}", ipv6),}
}

match必须列举所有的可能，在某些情况下可以使用占位符 _ 和通配 other 来保证列举所有可能

fn MatchNum0(num: i32) {match num {0 => println!("zero"),1 => println!("one"),_ => println!("other"),}
}fn MatchNum1(num: i32) {match num {0 => println!("zero"),1 => println!("one"),other => println!("other: {}", other),}
}

可以使多个模式匹配一种结果

fn MatchNum(num: i32) {match num {0 | 1 => println!("zero or one"),_ => println!("other"),}
}

匹配结构体

struct User {age: u8,name: String,sex: char
}fn MatchUser(user: User) {match user {User { age: 10, name, sex } => println!("I'm {}, age is 10", if sex == '0' {"girl"} else {"boy"}),User { age: 12, name, sex: '0' } => println!("I'm girl, age is 12"),_ => {println!("other age")}}
}

if let匹配

某些情况下可以使用if let这种匹配简单的匹配

fn MatchNum(num: Option<i32>) {if let Some(num ) = num {println!("number: {}", num)} else {println!("none")}
}