The simplest member function are those we defined to extract the real and imaginary part of a variable. Here you have to recall that these are private data, that is they invisible for users of the class. We obtain a copy of these variables by defining the functions
double Complex:: Re () const { return re; }} // getting the real part
double Complex:: Im () const { return im; } // and the imaginary part
Note that we have introduced the declaration const. What does it mean?
This declaration means that a variabale cannot be changed within a called function.