C++ Primer Plus

Creating Friends

The first step toward creating a friend function is to place a prototype in the class declaration and prefix the declaration with the keyword friend:

friend Time operator*(double m, const Time & t);  // goes in class declaration

This prototype has two implications:

• Although the operator*() function is declared in the class declaration, it is not a member function. So it isn’t invoked by using the membership operator.

• Although the operator*() function is not a member function, it has the same access rights as a member function.

The second step is to write the function definition. Because it is not a member function, you don’t use the Time:: qualifier. Also you don’t use the friend keyword in the definition. The definition ...