結構體和方法

use std::fmt;

#[derive(Debug)]
struct Rectangle {
    width: u32,
    height: u32,
}

impl std::fmt::Display for Rectangle {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Rectangle width: {} height: {}", self.width, self.height)
    }
}

impl Rectangle {
    fn area(
 
&self) -> u32 {
        self.width * self.width
    }

    fn can_hold(&self, other: &Rectangle) -> bool {
        self.width > other.width && self.height > other.height
    }

    fn square(size: u32) -> Rectangle {
        Rectangle {
            width: size,
            height: size,
        }
    }
}

fn main() {
    let rect1 
 
= Rectangle { width: 30, height: 50 };
    let rect2 = Rectangle { width: 10, height: 40 };
    let rect3 = Rectangle { width: 60, height: 45 };
    let rect4 = Rectangle::square(40);

    println!("Can rect1 hold rect2? {}", rect1.can_hold(&rect2));
    println!("Can rect1 hold rect3? {}", rect1.can_hold(&rect3));

    println
 
!("rect4 is {}", rect4);
    println!("rect4 is {:#?}", rect4);
    println!(
        "The area of the rectangle is {} square pixels.",
        rect4.area()
    );
}

結構體和方法