////   This file contains the C++ code from Program A.4 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm0A_04.cpp//Complex::Complex () :    real (0), imag (0)    {}Complex::Complex (double x) :    real (x), imag (0)    {}Complex::Complex (double x, double y) :    real (x), imag (y)    {}Complex::Complex (Complex const& c) :    real (c.real), imag (c.imag)    {}Complex::~Complex ()    {}