Rust基础(4)-结构体和方法

结构体和方法

结构体

1. 定义结构体
2. 创建结构体实例
3. 修改结构体字段
4. 参数名字和字段名字同名的简写方法
5. 从其它结构体创建实例
6. 元组结构体
7. 没有任何字段的类单元结构体
8. 打印结构体

fn main() {
    //1. 定义结构体
    #[derive(Debug)]
    struct User {
        name: String,
        count: String,
        nonce: u64,
        active: bool,
    }
    //2. 创建结构体实例
    let xiaoming = User {
        name: String::from("xiaoming"),
        count: String::from("80001000"),
        nonce: 10000,
        active: true,
    };
    //3. 修改结构体字段
    let mut xiaohuang = User {
        name: String::from("xiaohuang"),
        count: String::from("80001000"),
        nonce: 10000,
        active: true,
    };
    xiaohuang.nonce = 20000;
    //4. 参数名字和字段名字同名的简写方法
    let name = String::from("xiaoxiao");
    let count = String::from("89077777");
    let active = false;
    let nonce = 30000;
    /*let user1 = User{  //太繁琐
        name: name,
        count:count,
        nonce:nonce,
        active:active,
    };*/
    let user1 = User {   //简写
        name,
        count,
        nonce,
        active,
    };
    //5. 从其它结构体创建实例
    let user2 = User {
        ..user1   //user1被移动，之后不能再使用 user1
    };
    println!("name = {}", user2.name);
    let user3 = User {
        name: String::from("user3"),
        ..user2
    };
    println!("name = {}", user3.name);
    //6. 元组结构体
    //6.1 字段没有名字
    //6.2 圆括号
    struct Point(i32, i32);
    let a = Point(10, 20);
    let b = Point(30, 11);
    println!("a.x = {},a.y = {}", a.0, a.1);
    //7. 没有任何字段的类单元结构体
    struct A {}
    //8. 打印结构体
    //结构体上方加上：#[derive(Debug)]
    println!("xiaoming = {:?}", xiaoming);
    //可自动换行
    println!("xiaoming = {:#?}", xiaoming);
}

方法

1. 方法可以写在不同的impl语句块
2. 可以对外静态方法，需要通过：Dog::show()方式调用

#[derive(Debug)]
struct Dog {
    name: String,
    weight: f32,
    height: f32,
}

impl Dog {
    fn get_name(&self) -> &str {
        &(self.name[..])
    }
    fn get_weight(&self) -> f32 {
        self.weight
    }
    //此方法没有传入self，类似对外的静态方法，需要用 Dog::show()调用
    fn show(){
        println!("oh oh oh");
    }
}
impl Dog{
    fn get_height(&self) -> f32 {
        self.height
    }
}

fn main() {
    let dog = Dog {
        name: String::from("wangcai"),
        weight: 100.0,
        height: 70.5,
    };
    println!("dog = {:#?}",dog);
    println!("name = {}",dog.get_name());
    println!("weight = {}",dog.get_weight());
    Dog::show();
}

总结

已编辑完毕

参考

[1] Rust 程序设计语言