Gets an array dimension.

template <class Ty, unsigned I = 0>
struct extent;

Ty
The type to query.

I
The array bound to query.

If Ty is an array type that has at least I dimensions, the type query holds the number of elements in the dimension specified by I. If Ty is not an array type or its rank is less than I, or if I is zero and Ty is of type "array of unknown bound of U", the type query holds the value 0.

// std__type_traits__extent.cpp
// compile with: /EHsc
#include <type_traits>
#include <iostream>

int main()
    {
    std::cout << "extent 0 == "
        << std::extent<int[5][10]>::value << std::endl;
    std::cout << "extent 1 == "
        << std::extent<int[5][10], 1>::value << std::endl;

    return (0);
    }

extent 0 == 5
extent 1 == 10

Header: <type_traits>

Namespace: std

<type_traits>
remove_all_extents Class
remove_extent Class