README

Sample code to print area of shapes.
The purpose of shapes-area is for learning to use trait, Generic Types in Rust.
The program will create 3 kinds of shapes:

• a Triangle
• a Rectangle
• a Round

Every type of shapes implements a trait named AreaCalculable, which defines a area() fucntion. The main() fuction pass the AreaCalculable Type to a function print_area(), which will print the area value of the specific type.

The repo is orgnized with mod.

If want to try in playground, you also can use the simlified code as below:

fn main() {
    let shape_1 = Triangle { bot_edge: 4.0, height: 3.0, };
    let shape_2 = Rectangle { width: 10.0, height: 8.0, };
    let shape_3 = Round { radius: 5.0 };
    print_area(&shape_1);
    print_area(&shape_2);
    print_area(&shape_3);
}

fn print_area<T: AreaCalculable>(shape: &T) {
    println!("The area is: {:?}", shape.area());
}

pub trait AreaCalculable {
    fn area(&self) -> f32;
}

pub struct Triangle {
    pub bot_edge: f32,
    pub height: f32,
}

impl AreaCalculable for Triangle {
    fn area(&self) -> f32 {
        self.bot_edge * self.height * 0.5
    }
}

pub struct Rectangle {
    pub width: f32,
    pub height: f32,
}

impl AreaCalculable for Rectangle {
    fn area(&self) -> f32 {
        self.width * self.height
    }
}

pub struct Round {
    pub radius: f32,
}

impl AreaCalculable for Round {
    fn area(&self) -> f32 {
        self.radius * self.radius * 3.1415926
    }
}