std::input_or_output_iterator

 

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Iterator library

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indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) is-integer-like is-signed-integer-like (C++20)(C++20)	sentinel_for (C++20) sized_sentinel_for (C++20) input_iterator (C++20) output_iterator (C++20) input_or_output_iterator (C++20)	forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
Iterator primitives
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)
Algorithm concepts and utilities
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indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)	indirect_unary_predicate (C++20) indirect_binary_predicate (C++20)	indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
Common algorithm requirements
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20)	indirectly_copyable_storable (C++20)   indirectly_swappable (C++20) indirectly_comparable (C++20)	permutable (C++20) mergeable (C++20) sortable (C++20)
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indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
Iterator adaptors
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 input_or_output_iterator =         requires(I i){             {*i }->/*can-reference*/;         }&&         std::weakly_incrementable<I>;		(since C++20)

The input_or_output_iterator concept forms the basis of the iterator concept taxonomy; every iterator type satisfies the input_or_output_iterator requirements.

The exposition-only concept /*can-reference*/ is satisfied if and only if the type is referenceable.

Notes

input_or_output_iterator itself only specifies operations for dereferencing and incrementing an iterator. Most algorithms will require additional operations, for example:

• comparing iterators with sentinels (see sentinel_for);
• reading values from an iterator (see indirectly_readable and input_iterator);
• writing values to an iterator (see indirectly_writable and output_iterator);
• a richer set of iterator movements (see forward_iterator, bidirectional_iterator, random_access_iterator).

Unlike the LegacyIterator requirements, the input_or_output_iterator concept does not require copyability.

*i is required to be equality-preserving, although the increment operations required by weakly_incrementable are not.

Example

A minimum iterator.

#include <cstddef>#include <iterator>   struct SimpleIterator {using difference_type =std::ptrdiff_t;   int operator*();   SimpleIterator& operator++();void operator++(int){++*this;}};   static_assert(std::input_or_output_iterator<SimpleIterator>);