rust struct

struct.rs

fn main() {
    // 結構
    // https://doc.rust-lang.org/rust-by-example/custom_types/structs.html

    #[derive(Debug)]
    struct User {
        username: String,
        email: String,
    }

    let user1 = User {
        email: String::from("another@example.com"),
        username: String::from("anotherusername567"),
    };

    println!("\n1. basically");
    println!("user1 => {:?}", user1);
    println!("user1.email => {}", user1.email);
    println!("user1.username => {}", user1.username);

    let user2 = User {
        email: String::from("xxxx@example.com"),
        ..user1
    };
    println!("使用..語法指定了剩餘未設置的欄位與給定對應字段相同的值");
    println!("user2 => {:?}", user2);
    println!("user2.email => {}", user2.email);
    println!("user2.username => {}", user2.username);

    // A tuple struct
    #[derive(Debug)]
    struct CarPrice(String, u32);

    let carprice = CarPrice(String::from("Benz"), 2000);
    println!("\n2. A tuple struct");
    println!("carprice => {:?}", carprice);
    println!("car name {} , car price {}", carprice.0, carprice.1);

    #[derive(Debug)]
    struct CarBox {
        // A rectangle can be specified by where the top left and bottom right
        // corners are in space.
        top: CarPrice,
        bottom: CarPrice,
    };

    let _box = CarBox {
        top: CarPrice(String::from("Benz"), 2000),
        bottom: CarPrice(String::from("BMW"), 1500),
    };

    println!("Structs can be reused as fields of another struct");
    println!("car box => {:?}", _box);

    // Destructure a tuple struct
    let CarPrice(ss, pp) = carprice;
    println!("\ndestructure a tuple struct");
    println!("car name => {}", ss);
    println!("car price => {}", pp);

    // A unit struct
    #[derive(Debug)]
    struct Nil;

    let nil = Nil;

    println!("\n3. A unit struct");
    println!("nil => {:?}", nil);
}