std::ranges::views::stride,std::ranges::stride_view(3)

NAME
std::ranges::views::stride,std::ranges::stride_view - std::ranges::views::stride,std::ranges::stride_view

Synopsis
   Defined in header <ranges>
   template< ranges::input_range V >
       requires ranges::view<V> (1) (since C++23)
   class stride_view
       : public ranges::view_interface<stride_view<V>>
   namespace views {
       inline constexpr /* unspecified */ stride = /* unspecified */; (2) (since C++23)
   }
   Call signature
   template< ranges::viewable_range R >
   constexpr ranges::view auto stride( R&& r, (since C++23)
   ranges::range_difference_t<R> n );
   template< class DifferenceType > (since C++23)
   constexpr /*range adaptor closure*/ stride( DifferenceType&& n );
   Helper templates
   1) stride_view is a range adaptor that takes a view and a number n and produces a
   view, that consists of elements of the original view by advancing over n elements at
   a time. This means that each m^th element of the produced view is (n * i)^th element
   of the original view, for some non-negative index i. The elements of the original
   view, whose "index" is not a multiple of n, are not present in the produced view.
   Let S be the size of the original view. Then the size of produced view is:
     * (S / n) + (S % n ? 1 : 0), if S >= n; otherwise,
     * 1, if S > 0; otherwise,
     * 0, and the resulting view is empty.
   2) The name views::stride denotes a RangeAdaptorObject. Given subexpressions e and
   n, the expression views::stride(e, n) is expression-equivalent to stride_view(e, n).
   The n must be greater than 0, otherwise the behavior is undefined.
   stride_view always models input_range, and models forward_range,
   bidirectional_range, random_access_range, and/or sized_range, if adapted view type V
   models the corresponding concept. stride_view<V> models common_range whenever the
   underlying view V does.

Member functions
   constructor constructs a stride_view
   (C++23) (public member function)
   stride returns the stored stride value
   (C++23) (public member function)
   base returns a copy of the underlying (adapted) view
   (C++23) (public member function)
   begin returns an iterator to the beginning
   (C++23) (public member function)
   end returns an iterator or a sentinel to the end
   (C++23) (public member function)
   size returns the number of elements. Provided only if the underlying
   (C++23) (adapted) range satisfies sized_range.
                 (public member function)
         Inherited from std::ranges::view_interface
   empty returns whether the derived view is empty. Provided if it satisfies
   (C++20) sized_range or forward_range.
                 (public member function of std::ranges::view_interface<D>)
   cbegin returns a constant iterator to the beginning of the range.
   (C++23) (public member function of std::ranges::view_interface<D>)
   cend returns a sentinel for the constant iterator of the range.
   (C++23) (public member function of std::ranges::view_interface<D>)
   operator bool returns whether the derived view is not empty. Provided if
   (C++20) ranges::empty is applicable to it.
                 (public member function of std::ranges::view_interface<D>)
   front returns the first element in the derived view. Provided if it
   (C++20) satisfies forward_range.
                 (public member function of std::ranges::view_interface<D>)
   back returns the last element in the derived view. Provided if it satisfies
   (C++20) bidirectional_range and common_range.
                 (public member function of std::ranges::view_interface<D>)
   operator[] returns the n^th element in the derived view. Provided if it satisfies
   (C++20) random_access_range.
                 (public member function of std::ranges::view_interface<D>)
   Deduction guides
   Nested classes
   iterator the iterator type
   (C++23) (exposition-only member class template*)
   Helper templates
   template< class V >
   inline constexpr bool ranges::enable_borrowed_range<stride_view<V>> = (since C++23)
       ranges::enable_borrowed_range<V>;
   This specialization of ranges::enable_borrowed_range makes stride_view satisfy
   borrowed_range when the underlying view satisfies it.

Notes
     Feature-test macro Value Std Feature
   __cpp_lib_ranges_stride 202207L (C++23) std::ranges::stride_view

Example
// Run this code
 #include <algorithm>
 #include <iostream>
 #include <ranges>
 #include <string_view>
 using namespace std::literals;
 void print(std::ranges::viewable_range auto&& v, std::string_view separator = " ")
 {
     for (auto const& x : v)
         std::cout << x << separator;
     std::cout << '\n';
 }
 int main()
 {
     print(std::views::iota(1, 13) | std::views::stride(3));
     print(std::views::iota(1, 13) | std::views::stride(3) | std::views::reverse);
     print(std::views::iota(1, 13) | std::views::reverse | std::views::stride(3));
     print("0x0!133713337*x//42/A$@"sv | std::views::stride(0B11) |
           std::views::transform([](char O) -> char { return 0100 | O; }),
           "");
 }

Output:
 1 4 7 10
 10 7 4 1
 12 9 6 3
 password

References
     * C++23 standard (ISO/IEC 14882:2023):
     * 26.7.31 Stride view [range.stride]

See also
   ranges::slide_view a view whose M^th element is a view over the M^th through (M +
   views::slide N - 1)^th elements of another view
   (C++23) (class template) (range adaptor object)
   ranges::chunk_view a range of views that are N-sized non-overlapping successive
   views::chunk chunks of the elements of another view
   (C++23) (class template) (range adaptor object)
   ranges::adjacent_view a view consisting of tuples of references to adjacent elements
   views::adjacent of the adapted view
   (C++23) (class template) (range adaptor object)
   ranges::filter_view a view that consists of the elements of a range that satisfies
   views::filter a predicate
   (C++20) (class template) (range adaptor object)