Method overriding by abstract class and abstract methods

Program

using System;

namespace Polymorphism

{

    class MethodOverriding2

    {

        abstract class Shape

        {

            public abstract int area();

        }

        class Rectangle : Shape

        {

            private int length, width;

            public Rectangle(int a = 0, int b = 0)

            {

                length = a;

                width = b;

            }

            public override int area()

            {

                return (width * length);

            }

        }

        static void Main(string[] args)

        {

            Rectangle r = new Rectangle(10, 7);

            double a = r.area();

            Console.WriteLine("Area of Rectangle is: {0}", a);

            Console.ReadKey();

        }

    }

}

Output

Area of Rectangle is: 70