std::tuple_size(std::array)

< cpp‎ | container‎ | array
Defined in header <array>
template< class T, std::size_t N >

struct tuple_size< std::array<T, N> > :
    std::integral_constant<std::size_t, N>

{ };
 (since C++11)

Provides access to the number of elements in an std::array as a compile-time constant expression.

Inherited from std::integral_constant

Member constants

value
[static]
 N, the number of elements in the array
(public static member constant)

Member functions

operator std::size_t
 converts the object to std::size_t, returns value
(public member function)
operator()
(C++14)
 returns value
(public member function)

Member types

Type Definition
value_type std::size_t
type std::integral_constant<std::size_t, value>

Example

#include <iostream>
#include <array>
 
template<class T>
void test(T)
{
    int a[std::tuple_size<T>::value]; // can be used at compile time
    std::cout << std::size(a) << '\n';
}
 
int main()
{
    std::array<float, 3> arr;
    test(arr);
}

Output:

3

See also

Structured binding (C++17) binds the specified names to sub-objects or tuple elements of the initializer
(C++11)
 obtains the size of tuple at compile time
(class template specialization)