Convert std::tuple to std::array C++11

Question

If I have std::tuple (where the type is homogeneous), is there a stock function or constructor to convert to std::array

Answer 1

Even if title says C++11 I think C++14 solution is worth sharing (since everyone searching for problem will come up here anyway). This one can be used in compile time (constexpr proper) and much shorter than other solutions.

#include 
#include 
#include 
#include 

// Convert tuple into a array implementation
template
constexpr decltype(auto) t2a_impl(const Tuple& a, std::index_sequence)
{
        return std::array{std::get(a)...};
}

// Convert tuple into a array
template
constexpr decltype(auto) t2a(const std::tuple& a)
{
        using Tuple = std::tuple;
        constexpr auto N = sizeof...(T) + 1;
        return t2a_impl(a, std::make_index_sequence());
}

int main()
{
    constexpr auto tuple = std::make_tuple(-1.3,2.1,3.5);
    constexpr auto array = t2a(tuple);

    static_assert(array.size() == 3, "err");

    for(auto k : array)
        std::cout << k << ' ';
    return 0;
}

Example