Polymorphism and Different Types of Polymorphism

Polymorphism

Run time compile time Or

Dynamic binding static binding Or

late binding early binding

Virtual fuctions operator overloading function overloading

• Linking a function call to the function definition is called as binding.

•  If the binding is done at compile time then it is called as compile time polymorphism. •Compile time polymorphism is achieved by using function overloading and operator

overloading.

• If the binding is done at run time then it is called as run time polymorphism. It is achieved by using virtual functions.

VIRTUAL FUNCTIONS:

• When the same function is used in both the base class and derived class and if a pointer of base class is used to access the members of the derived class , then the members appropriate to the base class is called.

Example:

#include

#include

class base

{

public:

void show()

{

cout <<”\n This is a base class\n”;

}

};

class derived : public base

{

public:

void show()

{

cout <<”\n This is a derived class\n”;

}

};

void main()

{

base b,*bptr;

bptr=&b;

bptr->show();

derived d;

bptr=&d;

bptr->show();

getch();

}

o/p

This is a base class

This is a base class

• This can be overcome by using virtual functions.

• The base class member functions should be preceeded by a keyword virtual.

Example:

#include

#include

class base

{

public:

virtual void show()

{

cout <<”\n This is a base class\n”;

}

};

class derived : public base

{

public:

void show()

{

cout <<”\n This is a derived class\n”;

}

};

void main()

{

base b,*bptr;

bptr=&b;

bptr->show();

derived d;

bptr=&d;

bptr->show();

getch();

}

o/p

This is a base class

This is a derived class