/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#include <cstdlib>class Coord {  private:    int x, y;  public:    Coord (int i1, int i2) : x(i1), y(i2) {    }    friend Coord operator- (Coord const& c1, Coord const& c2) {        return Coord(c1.x-c2.x, c1.y-c2.y);    }    Coord abs() {        return Coord(std::abs(x),std::abs(y));    }};