23 Iterators library [iterators]

23.3 Iterator requirements [iterator.requirements]

23.3.4 Iterator concepts [iterator.concepts] Concept ContiguousIterator [iterator.concept.contiguous]

The ContiguousIterator concept provides a guarantee that the denoted elements are stored contiguously in memory.
template<class I>
  concept ContiguousIterator =
    RandomAccessIterator<I> &&
    DerivedFrom<ITER_CONCEPT(I), contiguous_iterator_tag> &&
    is_lvalue_reference_v<iter_reference_t<I>> &&
    Same<iter_value_t<I>, remove_cvref_t<iter_reference_t<I>>>;
Let a and b be dereferenceable iterators of type I such that b is reachable from a, and let D be iter_­difference_­t<I>.
The type I models ContiguousIterator only if addressof(*(a + D(b - a))) is equal to addressof(*a) + D(b - a).