/* 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. */// prime number computation by Erwin Unruhtemplate <int p, int i>class is_prime {  public:    enum { prim = (p==2) || (p%i) && is_prime<(i>2?p:0),i-1>::prim         }; }; template<>class is_prime<0,0> {  public:    enum {prim=1};}; template<>class is_prime<0,1> {  public:    enum {prim=1};}; template <int i>class D {  public:    D(void*);}; template <int i>class Prime_print {      // primary template for loop to print prime numbers  public:    Prime_print<i-1> a;     enum { prim = is_prime<i,i-1>::prim         };     void f() {        D<i> d = prim ? 1 : 0;        a.f();    } }; template<>class Prime_print<1> {   // full specialization to end the loop  public:    enum {prim=0};     void f() {        D<1> d = prim ? 1 : 0;    }; }; #ifndef LAST #define LAST 18 #endif int main(){    Prime_print<LAST> a;     a.f(); }