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std::input_or_output_iterator

From cppreference.com
< cpp‎ | iterator
 
 
Iterator library
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input_or_output_iterator
(C++20)
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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 (in particular, not void).

[edit] Notes

A typical input_or_output_iterator class only needs to be movable, and provide the following members:

  • Member typedef difference_type (used by std::iter_difference_t).
  • Prefix operator++ that returns a reference to *this.
  • Postfix operator++.
  • The dereference operator operator*.

Alternatively, the difference_type can be provided by specializing either std::iterator_traits or std::incrementable_traits. The functions can be defined as non-members, to be found by argument-dependent lookup.

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

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