C++ Primer Plus

Conversions and Friends

Let’s bring addition to the Stonewt class. As mentioned in the discussion of the Time class, you can use either a member function or a friend function to overload addition. (To simplify matters, assume that no conversion functions of the operator double() form are defined.) You can implement addition with the following member function:

Stonewt Stonewt::operator+(const Stonewt & st) const{    double pds = pounds + st.pounds;    Stonewt sum(pds);    return sum;}

Or you can implement addition as a friend function this way:

Stonewt operator+(const Stonewt & st1, const Stonewt & st2){    double pds = st1.pounds + st2.pounds;    Stonewt sum(pds);    return sum;}

Remember, you can provide the method definition or the friend definition ...