make_array.cc

#include <array>

template <typename... T>
using common_type_t = typename std::common_type<T...>::type;

template <typename T1, typename... T2>
constexpr auto make_array(T1&& t1, T2&&... t2)
	-> std::array<common_type_t<T1, T2...>, sizeof...(T2) + 1>
{
	return { std::forward<T1>(t1), std::forward<T2>(t2)... };
}


template <typename T, size_t N, size_t... I>
inline auto _make_array(T const (&arr)[N], std::index_sequence<I...>)
{
	return std::array<T, N>{{ arr[I]... }};
}

template <typename T, int N>
inline auto make_array(T const (&arr)[N])
{
	return _make_array(arr, std::make_index_sequence<N>());
}


#include <iostream>

int main()
{
	auto ch = 'a';
	const auto d = 65l;
	auto a1 = make_array(ch, d, 0);
	std::cout << a1[0] << std::endl;

	auto a2 = make_array("abc");
	std::cout << a2.data() << std::endl;

	std::string s1, s2;
	int pos;
	std::cin >> pos >> std::ws;
	getline(std::cin, s1);
	getline(std::cin, s2);
	auto a3 = make_array(s1, s2);
	std::cout << a3[pos] << std::endl;
}