template で fizzbuzz

fizzbuzz.cpp

#include <string>
#include <iostream>

template <bool cond>
struct print_if
{
    static void run(std::string msg) {}
};


template <>
struct print_if<true>
{
    static void run(std::string msg)
    {
        std::cout << msg << std::endl;
    }
};

template <>
struct print_if<false>
{
    static void run(std::string msg) {}
};
 
template <unsigned long N>
struct fizzbuzz
{
    static void run()
    {
        fizzbuzz<N-1>::run();

        print_if<N % 3 == 0 && N % 5 != 0>::run("Fizz");
        print_if<N % 3 != 0 && N % 5 == 0>::run("Buzz");
        print_if<N % 3 == 0 && N % 5 == 0>::run("FizzBuzz");
        print_if<N % 3 != 0 && N % 5 != 0>::run(std::to_string(N));
    }
};

template <>
struct fizzbuzz<0>
{
    static void run() {}
};

int main()
{
    fizzbuzz<15>::run();
}