/* 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. */template<typename T>class IsClassT {  private:    typedef char One;    typedef struct { char a[2]; } Two;    template<typename C> static One test(int C::*);    template<typename C> static Two test(...);  public:    enum { Yes = sizeof(IsClassT<T>::test<T>(0)) == 1 };    enum { No = !Yes };};