Theinput_or_output_iterator concept forms the basis of the iterator concept taxonomy; every iterator type satisfies theinput_or_output_iterator requirements.

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

[edit]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 (seesentinel_for);
• reading values from an iterator (seeindirectly_readable andinput_iterator);
• writing values to an iterator (seeindirectly_writable andoutput_iterator);
• a richer set of iterator movements (seeforward_iterator,bidirectional_iterator,random_access_iterator).

Unlike theLegacyIterator requirements, theinput_or_output_iterator concept does not require copyability.

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

[edit]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>);

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