Abstract Class With Abstract Method C# with Example

 using System;

namespace CSharpInheritance
{
	abstract class Shape
	{
		public double dim1, dim2;

		public Shape(double dimension1, double dimension2)
		{
			dim1 = dimension1;
			dim2 = dimension2;
		}

		abstract public double area();
	}
	class Rectangle : Shape
	{
		public Rectangle(double dimension1, double dimension2):base(dimension1, dimension2){}

		override public double area()
		{
			Console.WriteLine("\nInside Area for Rectangle : ");
			return dim1 * dim2;
		}
	}

	class Triangle : Shape
	{
		public Triangle(double dimension1, double dimension2):base(dimension1, dimension2){}

		override public double area()
		{
			Console.WriteLine("\nInside Area for Triangle : ");
			return dim1 * dim2 / 2;
		}
	}

	class AbstractClass
	{
		public static void Main(string[] args)
		{
			Rectangle newRectangle = new Rectangle(6,7);
			Triangle newTriangle = new Triangle(12,23);

			Shape referenceShape;

			referenceShape = newRectangle;
			Console.WriteLine("Area is " + referenceShape.area());

			referenceShape = newTriangle;
			Console.WriteLine("Area is " + referenceShape.area());
		}
	}
}