CPP virtual function

A virtual function in CPP is used to perform dynamic linkage or late binding on a function. Late binding is used to resolve a function call during runtime, thus allowing the compiler to bind the function call at runtime after determining the type of object. A virtual function can be simply understood as a member function in base class which is redefined in a derived class and is declared using the virtual keyword.

Example:

#include <iostream.h>  
using namespace std;  
class Base  
{  
public:  
virtual void print()  
{  
cout << "Hey, I am the Base."<<endl;  
}  
};  
class Derived:public Base
{  
public:  
void print()  
{  
cout << "Hey, I was Derived."<<endl;  
}  
};  
int main()  
{  
Base* b;	 
Derived d;	 
b = &d;  
b->print();   
}

Output

Hey, I was Derived.