#include <array>
#include <iostream>

// This function is th heart of the range loop. Returns
// an array that is allocated on the stack. Because this
// is a constexpr, this array of incrementing numbers is
// calculated at compile time. Please note that if negative
// numbers needs to be used, change \tparam T to a signed
// integer

/// @tparam The size of the array (number of iterations)
/// @tparam The type of int used to iterate
/// @param  The start number (defaults to 0)
/// @param  The step size (defaults to 1)
/// @return Statically created array. Contains the numbers to iterate over
template <size_t N, typename T = unsigned>
constexpr std::array<T, N> range(T b = 0, T s = 1) {
	std::array<T, N> ret{};
	
	for (auto& i : ret) {
		i = b;
		b += s;
	}
	
	return ret;
}

/// The practical way to use this 
void practical_way() {
	for (auto a : range<5>())
		std::cout << a << " ";
	std::cout << std::endl;
}

#define range(N)        range<N>()
// https://stackoverflow.com/questions/11761703/overloading-macro-on-number-of-arguments
// #define range(B, E)     range<(E) - (B)>(B)
//#define range(B, E, S)  range<((E) - (B) / (S))>((B), (S))
#define for(x) for(auto x)
#define in :

// The over-the-top way to do it
// see macro's above
void impractical_way() {
	for(a in range(5))
		std::cout << a << " ";
	std::cout << std::endl;
}


int main() {
	practical_way();
	impractical_way();
}