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

You can do it non-recursively:

#include 
#include 
#include   // see below

template
  using Array = std::array;

template
  inline Array
  tuple_to_array2(const std::tuple& t, redi::index_tuple)
  {
    return Array{ std::get(t)... };
  }

template
  inline Array
  tuple_to_array(const std::tuple& t)
  {
    using IndexTuple = typename redi::make_index_tuple<1+sizeof...(U)>::type;
    return tuple_to_array2(t, IndexTuple());
  }

See https://gitlab.com/redistd/redistd/blob/master/include/redi/index_tuple.h for my implementation of index_tuple, something like that is useful for working with tuples and similar variadic templates. A similar utility was standardised as std::index_sequence in C++14 (see index_seq.h for a standalone C++11 implementation).