merits and demerits of friend function

merits:

   we can able to access the other class members in our class if,we use friend keyword.

   we CAN access the members without inheriting the class.

demerits:

  Maximum size of the memory will occupied by objects according to the size of friend Members.

  we cant do any run time ploymorphism concepts in those members.

1) Sometimes a friend function allows a more obvious syntax for calling a function rather than what a member function can do.
2) Friend function is used to increase versatility of overload operator.