C++ Polymorphism

C++ Polymorphism

The term Polymorphism get derived from the Greek word where poly + morphos where poly means many and morphos means forms.

In programming background, polymorphism can be broadly divided into two parts. These are:

• Static Polymorphism
• Dynamic Polymorphism.

Polymorphism is another concept of object oriented programming (OOPs). The attitude which lies beneath this concept is “single interface having multiple implementations.” This provides a single interface for controlling access to a general class of actions. Polymorphism can be gained in both ways:

• compile time and
• run time

A common and simple example of polymorphism is when you used >> and <<as operator overloading in C++, for cin and cout statements respectively. This bitwise shift operator at that time acts as a inclusion operator and its overloaded meaning is defined in iostream header file.

Static Polymorphism

In static polymorphism or early binding, there you will get two sub categories like:

• Function overloading which is the process of using the same name for two or more functions.
• Operator overloading which is the process of using the same operator for two or more operands.

Code Snippet for Function Overloading

class funcOl {
public:
      funcOl ();
      funcOl (int i);
      int add(int a, int b);
      int add(float a, float b);
};

Code snippet for Operator Overloading

class calc {
public:
       // + operator overloading technique
       int operator+(calc g);
private:
    int k;
};

It is to be noted that function overloading can be done and is possible only based on:

• the return type of that overloaded function
• the type of parameters and its arrangement
• based on the number of parameters

Dynamic Polymorphism

This refers to the entity which changes its form depending on circumstances at run time. This concept can be adopted as analogous to a chameleon changing its color at the sight of an approaching object.

What is a Virtual Function?

A virtual function can be defined as the member function within a base class which you expect to redefine in derived classes. For creating a virtual function, you have to precede your function’s declaration within the base class with a virtual keyword.

Example of how to use virtual function

Example:

#include <iostream>
using namespace std;

class Game 
{ 
   int g; 
   public: 
       Game() 
       {
          g = 1; 
       } 
       virtual void show() 
       { 
          cout <<g;
       } 
};

class Anim: public Game 
{ 
   int k; 
   public: 
       Anim() 
       { 
          k = 2; 
       }
       virtual void show() 
       { 
          cout <<k; } }; int main() { Game *g; Anim a; g = &a; g->show(); 
   return 0; 
}