std::input_or_output_iterator - cppreference.com (original) (raw)

| | | | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------- | | 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.

[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 (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.

[edit] Example

A minimum iterator.

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