std:: input_or_output_iterator

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Iterator library
Iterator concepts
input_or_output_iterator
(C++20)

Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(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:

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>);