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Showing content from https://en.cppreference.com/w/cpp/language/../algorithm/../ranges/adjacent_view.html below:

std::ranges::views::adjacent, std::ranges::adjacent_view, std::ranges::views::pairwise - cppreference.com

std::ranges::adjacent_view 1) adjacent_view

is a range adaptor that takes a

view

, and produces a

view

whose

i^th

element (a âwindowâ) is a

std::tuple

that holds

N

references to the elements

[i, i + N - 1]

of the original view.

Let

S

be the size of the original view. Then the size of produced view is:

S - N + 1, if S >= N,
â0â otherwise, and the resulting view is empty.

3)

The name

views::pairwise

denotes a

RangeAdaptorObject

that behaves exactly as

views::adjacent<2>

adjacent_view always models forward_range, and models bidirectional_range, random_access_range, or sized_range if adapted view type models the corresponding concept.

[edit] Data members Member Description V base_ the underlying view
(exposition-only member object*) [edit] Member functions constructs a adjacent_view
(public member function) [edit] returns an iterator to the beginning
(public member function) [edit] returns an iterator or a sentinel to the end
(public member function) [edit] returns the number of elements, provided only if the underlying (adapted) range satisfies sized_range
(public member function) [edit] returns the approximate size of the resulting approximately_sized_range
(public member function) [edit] Inherited from std::ranges::view_interface returns whether the derived view is empty, provided only if it satisfies sized_range or forward_range
(public member function of std::ranges::view_interface<D>) [edit] returns a constant iterator to the beginning of the range
(public member function of std::ranges::view_interface<D>) [edit] returns a sentinel for the constant iterator of the range
(public member function of std::ranges::view_interface<D>) [edit] returns whether the derived view is not empty, provided only if ranges::empty is applicable to it
(public member function of std::ranges::view_interface<D>) [edit] returns the first element in the derived view, provided if it satisfies forward_range
(public member function of std::ranges::view_interface<D>) [edit] returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range
(public member function of std::ranges::view_interface<D>) [edit] returns the n^th element in the derived view, provided only if it satisfies random_access_range
(public member function of std::ranges::view_interface<D>) [edit] [edit] Deduction guides

(none)

[edit] Nested classes the iterator type
(exposition-only member class template*) the sentinel type used when adjacent_view is not a common_range
(exposition-only member class template*) [edit] Helper templates

This specialization of ranges::enable_borrowed_range makes adjacent_view satisfy borrowed_range when the underlying view satisfies it.

[edit] Notes

views::adjacent only accepts forward ranges even when N is 0.

There are similarities between ranges::adjacent_view and ranges::slide_view:

Both create âsliding windowâ of size N.
Both have the same size S - N + 1, where S is the size of an adapted view such that S >= N > 0.

The following table shows the differences between these adaptors:

[edit] Example

#include <array>
#include <format>
#include <iostream>
#include <ranges>
#include <tuple>
 
int main()
{
    constexpr std::array v{1, 2, 3, 4, 5, 6};
    std::cout << "v = [1 2 3 4 5 6]\n";
 
    for (int i{}; std::tuple t : v | std::views::adjacent<3>)
    {
        auto [t0, t1, t2] = t;
        std::cout << std::format("e = {:<{}}[{} {} {}]\n", "", 2 * i++, t0, t1, t2);
    }
}

Output:

v = [1 2 3 4 5 6]
e = [1 2 3]
e =   [2 3 4]
e =     [3 4 5]
e =       [4 5 6]

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior LWG 4098 C++23 views::adjacent<0> used to accept input-only ranges made rejected [edit] References

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

26.7.25 Adjacent view [range.adjacent]

[edit] See also

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