# extent_d template function

## Syntax

    template<int DimensionT, typename ObjT>
    auto extent_d(const ObjT &a_obj)

## Description

The template function offers a consistent way to determine the extent of a dimension for a multi-dimensional object. It can avoid extracting an entire n_extent_t<…> when only the extent of a single dimension is needed.

Template Argument | Description
--- | ---
    int DimensionT
| 0 based index starting at the leftmost dimension indicating which n-dimensions to query the extent of. Requirements: DimensionT >=0 and DimensionT < ObjT::rank
    typename ObjT
| The type of n-dimensional object from which to retrieve the extent. Requirements: ObtT is one of: n_container<…> n_extent_t<…> n_extent_generator<…>

Returns

The correctly typed extent corresponding to the requested DimensionT of a_obj.

Example

    template <typename VolumeT>
    void foo(const VolumeT & a_volume)
    {
        int extent_z = extent_d<0>(volume);
        int extent_y = extent_d<1>(volume);
        int extent_x = extent_d<2>(volume);
        /…
    }

Parent topic: n_container