Parent obj = new child() c# (Polymorphism)

public class A

    {

        public A()

        {

            Console.WriteLine("A");

        }

        public virtual void method()

        {

            Console.WriteLine("AM");

        }

    }

    public class B : A

    {

        public B()

        {

            Console.WriteLine("B");

        }

        public new void method()

        {

            Console.WriteLine("BM");

        }

    }

Always Declare Behind (Parent) 1st B obj = new A(); X A obj = new B(); output A B AM, because linking to virtual A method. New void or normal void also is this result

B obj = new B(); output A B BM, direct call B method

A < B = B is A (Child is Parent)

Child obj = new Parent() is not possible, Parent is not Child

If change to public override void method()

All output is A B BM

Why want call like this? Why not call A obj = new A();

Because you want to use all these child classes through the interface / methods defined on your parent class.

·

http://www.akadia.com/services/dotnet_polymorphism.html

http://www.codeproject.com/Articles/816448/Virtual-vs-Override-vs-New-Keyword-in-Csharp