In C++, friend functions of the class are allowed access to the class's private and protected members. They are specified globally, outside of the scope of the class. Friend functions are not class member functions. So, now what is friend function? Data members, class functions, or function templates are examples of these members. In such circumstances, we add the desired function as a buddy to both of these classes, allowing access to the class's secret and protected data members. What Is Friend Function in C++ | DataTrained
https://www.behance.net/gall...