C++模板求n!与1+2+...n

//求n!与1+2+...n#include <iostream>using namespace std;template<int _N=0>class A{    public:    //static int const result = 3*A<_N-1>::result;    enum{result=_N*A<_N-1>::result};//求n!    //enum{result=_N+A<_N-1>::result};//求1+...n。};template<>class A<1>{    public:    //static int const result = 1;    enum{result=1};};int main(){    cout<<A<3>::result<<endl;    return 0;}