std::contiguous_iterator

 

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input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20)	iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)	iterator (deprecated in C++17) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
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reverse_iterator make_reverse_iterator (C++14) move_iterator (C++11) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)	front_insert_iterator back_insert_iterator inserter insert_iterator front_inserter back_inserter move_sentinel (C++20)	common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) make_const_iterator (C++23) make_const_sentinel (C++23)
Stream iterators istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	Iterator customization points ranges::iter_move (C++20) ranges::iter_swap (C++20)
Iterator operations advance distance prev (C++11)   next (C++11) ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)	Range access begincbegin (C++11)(C++14) rbegincrbegin (C++14)(C++14)   endcend (C++11)(C++14) rendcrend (C++14)(C++14)   sizessize (C++17)(C++20) empty (C++17) data (C++17)

 

Defined in header <iterator>
template< class I >     concept contiguous_iterator =         std::random_access_iterator<I> &&         std::derived_from</*ITER_CONCEPT*/<I>, std::contiguous_iterator_tag> &&         std::is_lvalue_reference_v<std::iter_reference_t<I>> &&         std::same_as<             std::iter_value_t<I>, std::remove_cvref_t<std::iter_reference_t<I>>         > &&         requires(const I& i) {             { std::to_address(i) } ->               std::same_as<std::add_pointer_t<std::iter_reference_t<I>>>;         };		(since C++20)

The contiguous_iterator concept refines random_access_iterator by providing a guarantee the denoted elements are stored contiguously in the memory.

Iterator concept determination

Definition of this concept is specified via an exposition-only alias template /*ITER_CONCEPT*/.

In order to determine /*ITER_CONCEPT*/<I>, let ITER_TRAITS<I> denote I if the specialization std::iterator_traits<I> is generated from the primary template, or std::iterator_traits<I> otherwise:

• If ITER_TRAITS<I>::iterator_concept is valid and names a type, /*ITER_CONCEPT*/<I> denotes the type.
• Otherwise, if ITER_TRAITS<I>::iterator_category is valid and names a type, /*ITER_CONCEPT*/<I> denotes the type.
• Otherwise, if std::iterator_traits<I> is generated from the primary template, /*ITER_CONCEPT*/<I> denotes std::random_access_iterator_tag.
• Otherwise, /*ITER_CONCEPT*/<I> does not denote a type and results in a substitution failure.

Semantic requirements

Let a and b be dereferenceable iterators and c be a non-dereferenceable iterator of type I such that b is reachable from a and c is reachable from b. The type I models contiguous_iterator only if all the concepts it subsumes are modeled and:

• std::to_address(a) == std::addressof(*a),
• std::to_address(b) == std::to_address(a) + std::iter_difference_t<I>(b - a), and
• std::to_address(c) == std::to_address(a) + std::iter_difference_t<I>(c - a).

Equality preservation

Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).

Implicit expression variations

A requires expression that uses an expression that is non-modifying for some constant lvalue operand also requires implicit expression variations.

Notes

contiguous_iterator is modeled by every pointer type to complete object type.

Iterator types in the standard library that are required to satisfy the LegacyContiguousIterator requirements in C++17 are also required to model contiguous_iterator in C++20.

See also

random_access_iterator (C++20)

specifies that a bidirectional_iterator is a random-access iterator, supporting advancement in constant time and subscripting (concept)