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std::tuple_element<std::array>

From cppreference.com
< cpp‎ | container‎ | array
Defined in header <array>
template< std::size_t I, class T, std::size_t N >
struct tuple_element<I, std::array<T, N> >;
(since C++11)

Provides compile-time indexed access to the type of the elements of the array using tuple-like interface.

Contents

[edit] Member types

Member type Definition
type the type of elements of the array

[edit] Possible implementation

template<std::size_t I, class T>
  struct tuple_element;
 
template<std::size_t I, class T, std::size_t N>
  struct tuple_element<I, std::array<T,N> >
  {
     using type = T;
  };

[edit] Example

#include <array>
#include <iostream>
#include <tuple>
#include <type_traits>
 
int main()
{
   // define array and get the type of the element at position 0
   std::array<int, 10> data {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
   using T = std::tuple_element<0, decltype(data)>::type; // int
 
   std::cout << std::boolalpha;
   std::cout << std::is_same<T, int>::value << '\n';
 
   const auto const_data = data;
   using CT = std::tuple_element<0, decltype(const_data)>::type; // const int
 
   // the result of tuple_element depends on the cv-qualification of the tuple-like type
   std::cout << std::is_same<T, CT>::value << '\n';
   std::cout << std::is_same<CT, const int>::value << '\n';
}

Output:

true
false
true

[edit] See also

obtains the type of the specified element
(class template specialization) [edit]
obtains the type of the elements of pair
(class template specialization) [edit]