# std::experimental::make_array

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< cpp‎ | experimental

Defined in header `<experimental/array>` |  |
template <class D = void, class... Types> constexpr std::array <VT /* see below */, sizeof...(Types)> make_array(Types&&... t); |  | (library fundamentals TS v2)

Creates a std::array whose size is equal to the number of arguments and whose elements are initialized from the corresponding arguments. Returns std::array <VT, sizeof...(Types)>{ std::forward <Types>(t)...}

If `D` is void, then the deduced type `VT` is std::common_type_t <Types...>. Otherwise, it is `D`.

If `D` is void and any of std::decay_t <Types>... is a specialization of std::reference_wrapper, the program is ill-formed.

### Possible implementation

    namespace details {
      template<class> struct is_ref_wrapper : std::false_type {};
      template<class T> struct is_ref_wrapper<std::reference_wrapper<T>> : std::true_type {};

      template<class T>
      using not_ref_wrapper = std::negation<is_ref_wrapper<std::decay_t<T>>>;

      template <class D, class...> struct return_type_helper { using type = D; };
      template <class... Types>
      struct return_type_helper<void, Types...> : std::common_type<Types...> {
          static_assert(std::conjunction_v<not_ref_wrapper<Types>...>,
                        "Types cannot contain reference_wrappers when D is void");
      };

      template <class D, class... Types>
      using return_type = std::array<typename return_type_helper<D, Types...>::type,
                                     sizeof...(Types)>;
    }

    template < class D = void, class... Types>
    constexpr details::return_type<D, Types...> make_array(Types&&... t) {
      return {std::forward<Types>(t)... };
    }

### Example

Run this code

    #include <experimental/array>
    #include <iostream>
    #include <type_traits>

    int main()
    {
        decltype(auto) arr = std::experimental::make_array(1, 2, 3, 4, 5);
        bool is_array_of_5_ints = std::is_same<decltype(arr), std::array<int, 5>>::value;
        std::cout << "Returns an array of five ints? ";
        std::cout << std::boolalpha << is_array_of_5_ints << '\n';
    }

Output:

    Returns an array of five ints? true

### See also

to_array | Creates a std::array object from a built-in array (function template)

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