Rust 结构体struct

struct  Rectangle {
    width: u32,
    length: u32,
}
fn main() {
    let ret = &Rectangle {
        width: 30,
        length: 50,
    };
    println!("The Area is {}", area(ret))
}

fn area(rect: &Rectangle) -> u32 {
    rect.width*rect.length
}