override_1.cs

    
    abstract class ShapesClass
    {
        abstract public int Area();
    }
    class Square : ShapesClass
    {
        int side = 0;

        public Square(int n)
        {
            side = n;
        }
        // Area method is required to avoid
        // a compile-time error.
        public override int Area()
        {
            return side * side;
        }

        static void Main() 
        {
            Square sq = new Square(12);
            Console.WriteLine("Area of the square = {0}", sq.Area());
        }

        interface I
        {
            void M();
        }
        abstract class C : I
        {
            public abstract void M();
        }

    }
    // Output: Area of the square = 144