Rust學習(13)：結構體

普通結構體

定義普通結構體以及結構體實例化

fn main(){
    struct User{
    username:String,    //字段
    email:String,
    sign_in_count:u64,
    active:bool,
    }

    let  user1 = User{
        email:String::from("[email protected]"),
        username:String::from("username123"),
        active:true,
        sign_in_count:1,
    };

    println!("{}, {}, {}, {}", user1.email, user1.username, user1.active, user1.sign_in_count);

    //整個實例必須是可變的；Rust 並不允許只將某個字段標記爲可變
     let mut user2 = User{
        email:String::from("[email protected]"),
        username:String::from("username123"),
        active:user1.active,
        sign_in_count:user1.sign_in_count,
    };

    user2.username = String::from("xixibiya");

    println!("{}, {}, {}, {}", user2.email, user2.username, user2.active, user2.sign_in_count);

    let  user3 = User{
        email:String::from("[email protected]"),
        username:String::from("username123"),
        ..user1   //爲一個 User 實例設置新的 email 和 username 值，不過其餘值來自 user1 變量中實例的字段
    };

    println!("{}, {}, {}, {}", user3.email, user3.username, user3.active, user3.sign_in_count);
}

使用結構體作爲返回值

struct User{
    username:String,
    email:String,
    sign_in_count:u64,
    active:bool,
}

fn main(){
    let user1 = build_user(String::from("[email protected]"), String::from("username123"));
    println!("{}, {}, {}, {}", user1.email, user1.username, user1.active, user1.sign_in_count);

    let user2 = build_user_two(String::from("[email protected]"), String::from("username123"));
    println!("{}, {}, {}, {}", user2.email, user2.username, user2.active, user2.sign_in_count);
}

fn build_user(email:String, username:String)->User{
    return User{
        email:email,
        username:username,
        active:true,
        sign_in_count:1,
    };
}

//參數名與字段名都完全相同,可以使用 字段初始化簡寫語法
fn build_user_two(email:String, username:String)->User{
    return User{
        email,
        username,
        active:true,
        sign_in_count:1,
    };
}

元組結構體

沒有具體的字段名，只有字段的類型

fn main(){
    struct Color(i32, i32, i32);
    struct Point(i32, i32, i32);

    let black = Color(0, 0, 0);
    let white = Color(1, 1, 1);
    println!("{}, {}", black.0, white.0);

    let point1 = Point(0, 0, 0);
    let point2 = Point(1, 1, 1);
    println!("{}, {}", point1.0, point2.0);
}

參考：https://kaisery.github.io/trpl-zh-cn/ch05-01-defining-structs.html?search=