文章目录
- match匹配
- [if let匹配](#if let匹配)
match匹配
match可以结合枚举使用,例如
rust
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
rust
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
rust
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
rust
fn MatchNum(num: i32) {
match num {
0 | 1 => println!("zero or one"),
_ => println!("other"),
}
}
匹配结构体
rust
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
rust
fn MatchNum(num: Option<i32>) {
if let Some(num ) = num {
println!("number: {}", num)
} else {
println!("none")
}
}