/* 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. */#ifndef POW3_HPP#define POW3_HPP// primary template to compute 3 to the Nthtemplate<int N>class Pow3 {  public:    enum { result = 3 * Pow3<N-1>::result };};// full specialization to end the recursiontemplate<>class Pow3<0> {  public:    enum { result = 1 };};#endif // POW3_HPP