変数を使わないで 0 から 100 まで

test.cpp

#include <iostream>


template <int start, int end>
class Sum
{
    template <int _start, int _end, int _result>
    class Internal
    {
    public:
        static const int value = Internal<_start, _end-1, _result+_end-1>::value;
    };

    template <int _start, int _result>
    class Internal<_start, _start, _result>
    {
    public:
        static const int value = _result;
    };

    template <int _start, int _end, bool result>
    class Compare;

    template <int _start, int _end>
    class Compare<_start, _end, true>
    {
    public:
        static const int value = Internal<_start, _end, _end>::value;
    };

    template <int _start, int _end>
    class Compare<_start, _end, false>
    {
    public:
        static const int value = Internal<_end, _start, _start>::value;
    };

public:
    static const int value = Compare<start, end, start<end>::value;
};


int main(const int argc, const char* const args[])
{
    std::cout << Sum<0, 100>::value << std::endl;
    std::cout << Sum<100, 0>::value << std::endl;
    
    return 0;
}