# std::extents<IndexType,Extents...>::extent

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< cpp‎ | container‎ | mdspan‎ | extents

constexpr index_type extent( rank_type i ) const noexcept; |  | (since C++23)

Returns dynamic extent size of an `extents` at a certain rank index.

### Parameters

i | - | The rank index to get the extent size of

### Return value

The dynamic extent size of an `extents` at a certain rank index.

### Example

Run this code

    #include <iostream>
    #include <mdspan>

    int main()
    {
        std::extents<int, 1, 2> e1;
        std::extents<int, 3, std::dynamic_extent, std::dynamic_extent> e2(4, 5);
        std::cout << e1.extent(0) << ", " << e1.extent(1) << '\n';
        std::cout << e2.extent(0) << ", " << e2.extent(1) << ", " << e2.extent(2) << '\n';
    }

Output:

    1, 2
    3, 4, 5

### See also

static_extent [static] | returns static extent size of an `extents` at a certain rank index (public static member function)
extent (C++11) | obtains the size of an array type along a specified dimension (class template)

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