复合类型

• 元组(tuple)
• 数组(array)
• 结构体(struct)
• 枚举(enum)

元组

fn main() {
    let tup: (i32, f64, u8) = (500, 6.4, 1);
    let (x, y, z) = tup;
    println!("The value of y is: {}", y); // 6.4

    let x: (i32, f64, u8) = (500, 6.4, 1);

    let five_hundred = x.0;

    let six_point_four = x.1;
    let one = x.2;
}

数组

fn main() {
    let months = ["January", "February", "March", "April", "May", "June", "July",
        "August", "September", "October", "November", "December"];
    let a: [i32; 5] = [1, 2, 3, 4, 5];
    let first = a[0];
    let second = a[1];
}

结构体

 #[derive(Debug)]
struct Rectangle {
    width: u32,
    height: u32,
}
// 专门定义结构体方法的
impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
}
fn main() {
    let rect1 = Rectangle { width: 30, height: 50 };

    println!("rect1 is {:?}", rect1);
    
    println!(
        "The area of the rectangle is {} square pixels.",
        rect1.area()
    );
}

枚举

// 关键字 enum 示例
#[derive(Debug)]  // 允许打印
enum IpAddrKind {
    V4,
    V6,
}
#[derive(Debug)]
struct IpAddr {
    kind: IpAddrKind,
    address: String,
}
fn main(){
    let home = IpAddr {
        kind: IpAddrKind::V4,
        address: String::from("127.0.0.1"),
    };

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