C# : Abstract class : Part 11

• It is not possible to create instance / object of abstract class
• An abstract class can be only used as base class
• It cannot be sealed.
• Abstract class can have fields.
• Class derived from abstract class must provide implementation of all abstract class members.

e.g.

namespace AbstractClass

{

    public abstract class Abstract1

    {

        public abstract int AddNumbers(int a, int b);

    }

    public class Class1 : Abstract1

    {

        public override int AddNumbers(int a, int b)

        {

            return a + b;

        }

    }

    class Program

    {

        static void Main(string[] args)

        {

            Class1 objClass1 = new Class1();

            var result = objClass1.AddNumbers(8, 4);

            Console.WriteLine("The result is {0}", result);

        }

    }

}