using System;

​

// 2nd, come here for an example class that is "implementing" the interface below

public class Rectangle : IShape

{

    // fields and properties

    private double length;

    private double width;

​

    // Method that IS REQUIRED by the interface

    public double getArea()

    {

        return length * width;

    }

    public string toString(){

        return "Converted to a string";

    }

    // constructor

    public Rectangle(double l, double w)

    {

        length = l;

        width = w;

    }

}

​

public class Triangle : IShape

{

    // fields and properties

    private double base1;

    private double height;

​

    // Method that IS REQUIRED by the interface

    public double getArea()

    {

        return base1 * height * 0.5;

    }

    public string toString(){

        return "Converted to a string";

    }

    // constructor

    public Triangle(double b, double h)

    {

        base1 = b;

        height = h;

    }

    public static void Main()

    {

        Rectangle rect1 = new Rectangle(100,100);

        Console.WriteLine("Rectangle's area is: " + rect1.getArea());

        Triangle tri1 = new Triangle(10,10);

        Console.WriteLine("Triangle's area is: " + tri1.getArea());

    }

}

// Start here: the interface

interface IShape

{   

    double getArea();

}