NAME¶

std::input_or_output_iterator - std::input_or_output_iterator

Synopsis¶

Defined in header <iterator>
template< class I >

concept input_or_output_iterator =
requires(I i) { (since C++20)
{ *i } -> /*can-reference*/;
} &&

std::weakly_incrementable<I>;

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 (in particular, not void).

This section is incomplete
Reason: Is *i required to be equality-preserving?

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.

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>);

Category:¶

* Todo with reason