Difference Between Friend Function and Virtual Function in C++

A friend class can access private and protected members of other classes in which it is declared as friend. It is sometimes useful to allow a particular class to access private members of other classes. Just likely, a friend function is a function that is declared outside the scope of a class. This function can be invoked like a normal function and include object/s as arguments. It is mostly used for overloading <<and>> for I/O. It can generally access any member of the class to which it is friend.  

Illustration: 

class GFG  
{ 
 private: 
 {  
 Public: 
 {  
 friend void check();  
 }
  
void check();  

Now coming onto the second function is a virtual function. So a virtual function is basically a member function of a class that is declared within the base class. In this, a virtual keyword is used to make member function of base class Virtual. It also supports polymorphism at both compile-time and run time. It also allows derived class to simply replace implementation that is provided or given by the base class.  

Illustration:  

class GFG  
{  
Public:  
          Virtual return_type function_name(arguments)  
         {  
         …..  
         }  
}:  
   class A  
  {  

By far we are clear with discussing friend function and virtual function, now let us see the major differences between them even to grasp a good grip over it.