std::ranges::adjacent_view<V,N>::iterator

template< bool Const >
class /*iterator*/

(since C++23)
(exposition only*)

The return type of adjacent_view::begin, and of adjacent_view::end when the underlying view V is a common_range.

The type /*iterator*/<true> is returned by the const-qualified overloads. The type /*iterator*/<false> is returned by the non-const-qualified overloads.

Member types

Member	Definition
`Base` (private)	`maybe-const` <Const,V> (exposition-only member type*)
`iterator_category`	`std::input_iterator_tag`
`iterator_concept`	`std::random_access_iterator_tag`, if `Base` models `random_access_range`. Otherwise, `std::bidirectional_iterator_tag`, if `Base` models `bidirectional_range`. Otherwise, `std::forward_iterator_tag`.
`value_type`	`std::tuple</REPEAT/(ranges::range_value_t<Base>, N)...>;`
`difference_type`	`ranges::range_difference_t<Base>`

Data members

Member	Description
`std::array<ranges::iterator_t<Base>, N>` `current_` (private)	an array of iterators (exposition-only member object*)

Member functions

(constructor)	constructs an iterator (public member function)
operator*	accesses the element (public member function)
operator[]	accesses an element by index (public member function)
operator++operator++(int)operator--operator--(int)operator+=operator-=	advances or decrements the underlying iterators (public member function)

Non-member functions

operator==operator<operator>operator<=operator>=operator<=> (C++23)	compares the underlying iterators (function)
operator+operator- (C++23)	performs iterator arithmetic (function)
iter_move (C++23)	casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function)
iter_swap (C++23)	swaps the objects pointed to by two underlying iterators (function)

Example

#include <cassert>
#include <concepts>
#include <list>
#include <ranges>
#include <tuple>
#include <utility>
#include <vector>

int main()
{
    auto v = std::vector{0, 1, 2, 3, 4, 5};
    auto i = (v | std::views::adjacent<3>).begin();
    using I = decltype(i);
    static_assert(std::same_as<I::value_type, std::tuple<int, int, int>>);
    static_assert(std::same_as<I::iterator_concept, std::random_access_iterator_tag>);
    // some of available operators:
    ++i; i++; --i; i--; i += 2; i -= 2;
    assert(i[2] == std::tuple(2, 3, 4));
    using DI = decltype(*i);
    static_assert(std::same_as<DI, std::tuple<int&, int&, int&>>);
    std::get<1>(*i) = 42; // modifies v[1] via iterator i
    assert(v[1] == 42);

    auto l = std::list{0, 1, 2, 3, 4, 5};
    auto j = (l | std::views::adjacent<3>).begin();
    using J = decltype(j);
    static_assert(std::same_as<J::value_type, std::tuple<int, int, int>>);
    static_assert(std::same_as<J::iterator_concept, std::bidirectional_iterator_tag>);
    ++j; --j; j++; j--; // some of available operators
    // j += 2; j -= 2;       // error: these operator are not available
    // std::ignore() = j[1]; //        for bidirectional iterator
}

References

C++23 standard (ISO/IEC 14882:2024):

26.7.25.3 Class template adjacent_view::iterator [range.adjacent.iterator]