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;
}