Abstract Classes

Abstract Classes:

1.The abstract keyword is used to create abstract classes.

2.An abstract class is incomplete hence can't be instantiated.

3.An abstract class can only be used as a base class.

4.An abstract class can only be sealed.

5.An abstract class may contain abstract members(method,properties,indexers and events),but not mandatory.

6.A non-abstract class derived from an abstract class must provide implementation for all inherited abstract members.

Example:

public abstract class Customer
    {
        public abstract void Print();
    }
    class Program:Customer
    {
        public override void Print()
        {
            Console.WriteLine("Abstract Print");
        }
        static void Main(string[] args)
        {
            Program p = new Program();
            p.Print();
            Console.ReadKey();
        }
    }