iterator.hpp contains ct_capacity, a constexpr function that returns the capacity of a container which is known at compile-time.

ct_capacity can be called with:

• std::array

• std::span (unless it has std::dynamic_extent)

• stdx::span (unless it has stdx::dynamic_extent)

• stdx::cx_map

• stdx::cx_multimap

• stdx::cx_queue

• stdx::cx_set

• stdx::cx_vector

ct_capacity_v is a corresponding variable template of type std::size_t.