Using the public interface of Employee in writing operator<< works, but there are more flexible choices.

• Write a public member of Employee - string toString() then write the overloaded operator<< like this:

   ostream& operator<<(ostream& os, const Employee& e)
   {
     os << e.toString();
     return os;
   }          
           
  

• The Employee class can declare the non-member function operator<< to be a friend function.

  Declaring a function to be a friend function of Employee means the function can access all members including private members of any Employee parameter passed to it.

The first choice has superior benefits for opertor<< in case subclasses of Employee are created later (such as a Manager subclass).