Polymorphism

What is polymorphism, and how is it implemented?

Polymorphism is one of the pillars of any object oriented programming language. Polymorphism enables us to write applications that process objects that share the same base class heirarchy as if they are all objects of the base class. With Polymorphism, the same method name and signature can be used to cause different actions to occur depending on the type of the object on which the method is invoked.

Ex:
public class Shape
{
public abstract double GetArea();
}

public class Rectangle : Shape
{
public override double GetArea()
{
return width * length;
}
}

public class Square : Shape
{
public override double GetArea()
{
return side * side;
}
}

In the above example, the user can take any shape object instance and call GetArea() method. Depending on the type of the object, the specific GetArea() is called and appropriate value is returned. Note all the methods (GetArea()) has the exact signature including the return type.