C++ Programming - Objects and Classes - Discussion

It is not the always the case, according to this link on stackoverflow:

It is required when a pointer of base class is cast to have derivedClas type, when we delete this pointer it is required to call derived class's destructor.

Friend function is only declared in the class. But why can't it be defined in main function, because we are only accessing the private data. So it can be access from anywhere in the program.

Friend functions can be applied only to functions which can access private members of a class. A non member function of a class can access private members using friend function.

Friend function only initialize in-between main and class.

Friend keyword can be used on main() ? please explain I didn't get ?

Yes we can use friend keyword on main by defining main as member function of a class. So the data members of even though it is private can be accessible in main function. And program will execute properly.

Because main is entry point function.

Please explain why friend keyword is not used with main()?

Friend keyword is written inside one class(class a) to inform the same class(class a) that another class(class b) can access the private data of the other(class a).

eg: class a class b
{ {
private : int e; private : int f;
public : int x;
friend class b; }
}

In the above example, class b can access the private data of the class a.

friend keyword can be used on main() also i.e we can make main() as friend function.