C# Hierarchical Inheritance using Interface

Program

using System;

namespace AboutClasses

{

    class Hierarchical_Inheritance_using_Interface

    {

        public interface IArea

        {

            void findArea();    //Signature or Declaration

        }

        class Circle : IArea

        {

            float rad, area;

            public Circle(float r)

            {

                rad = r;

            }

            public void DisplayRad()

            {

                Console.WriteLine("Radius is {0}", rad);

            }

            public void findArea()

            {

                area = 3.14f * (rad * rad);

                Console.WriteLine("Area of Circle {0}", area);

            }

        }

        class Cylinder : IArea

        {

            float rad, height, area;

            public Cylinder(float r, float h)

            {

                rad = r;

                height = h;

            }

            public void DisplayRadHgt()

            {

                Console.WriteLine("Radius is {0}", rad);

                Console.WriteLine("Height is {0}", height);

            }

            public void findArea()

            {

                area = 3.14f * (rad * rad) * height;

                Console.WriteLine("Area of cylinder {0}", area);

            }

        }

        static void Main(String[] args)

        {

            Circle cir = new Circle(10f);

            cir.DisplayRad();

            cir.findArea();

            Cylinder cyl = new Cylinder(10f, 5f);

            cyl.DisplayRadHgt();

            cyl.findArea();

            Console.ReadKey();

        }

    }

}

Output

Radius is 10
Area of Circle 314

Radius is  10
Height is 5

Area of cylinder 1570