Defined in header <array> | ||
|---|---|---|
template< std::size_t I, class T, std::size_t N > struct tuple_element<I, array<T, N> >; | (since C++11) |
Provides compile-time indexed access to the type of the elements of the array using tuple-like interface.
| Member type | Definition |
|---|---|
| type | the type of elements of the array |
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;
}; |
#include <array>
#include <iostream>
#include <tuple>
#include <type_traits>
int main()
{
// define compile time constant 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
| obtains the type of the specified element (class template specialization) |
|
|
(C++11) | obtains the type of the elements of pair (class template specialization) |
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