OOP .NET Interview question :- What is Polymorphism?

Poly means many. So how can we take this definition in .NET context. Well we can apply this to class’s ability to share the same methods (actions) but implement them differently.

Suppose we have a method in a class to add numbers,



public class calculation

{

public int add(int x, int y)

{

return x+y;

}

public int add(int x, int y,int z)

{

return x+y+z;

}

}

Types of Polymorphism

1) Static or Compile time Polymorphism

Which method is to be called is decided at compile-time only. Method Overloading is an example of this. Method overloading is a concept where we use the same method name many times in the same class, but different parameters. Depending on the parameters we pass, it is decided at compile-time only. The same method name with the same parameters is an error and it is a case of duplication of methods which c# does not permit. In Static Polymorphism decision is taken at compile time.

public Class StaticDemo

{

public void display(int x)

{

Console.WriteLine(“Area of a Square:”+x*x);

}

public void display(int x, int y)

{

Console.WriteLine(“Area of a Square:”+x*y);

}

public static void main(String args[])

{

StaticDemo spd=new StaticDemo();

Spd.display(5);

Spd.display(10,3);

}

}
2) Dynamic or Runtime Polymorphism.

Run time Polymorphism also known as method overriding. In this Mechanism by which a call to an overridden function is resolved at a Run-Time (not at Compile-time) if a base Class contains a method that is overridden. Method overriding means having two or more methods with the same name, same signature but with different implementation. In this process, an overridden method is called through the reference variable of a superclass, the determination of the method to be called is based on the object being referred to by reference variable.

Class BaseClass

{

Public void show ()

{

Console.WriteLine(“From base class show method”);

}

}

Public Class DynamicDemo : BaseClass

{

Public void show()

{

Console.WriteLine(“From Derived Class show method”);

}

Public static void main(String args[])

{

DynamicDemo dpd=new DynamicDemo ();

Dpd.show();


}

}