std::ranges::views::stride, std::ranges::stride_view

 

C++

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Feature test macros (C++20)

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Concepts library (C++20)

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Ranges library (C++20)

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Technical specifications

Symbols index

External libraries

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_trange_value_trange_reference_t	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)	elements_of (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Range factories
empty_viewviews::empty single_viewviews::single	iota_viewviews::iota repeat_viewviews::repeat (C++23)(C++23)	basic_istream_viewviews::istream
Range adaptors
views::all_tviews::all ref_view owning_view as_rvalue_viewviews::as_rvalue (C++23)(C++23) filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (C++23)(C++23) lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	reverse_viewviews::reverse as_const_viewviews::as_const (C++23)(C++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (C++23)(C++23) zip_viewviews::zip (C++23)(C++23) zip_transform_viewviews::zip_transform (C++23)(C++23)	adjacent_viewviews::adjacent (C++23)(C++23) views::pairwise (C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23) views::pairwise_transform (C++23) chunk_viewviews::chunk (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23) stride_viewviews::stride (C++23)(C++23) cartesian_product_viewviews::cartesian_product (C++23)(C++23)
Range generators
std::generator (C++23)
Range adaptor objects
Range adaptor closure objects
range_adaptor_closure (C++23)
Helper items
copyable-box movable-box (until C++23)(C++23)	simple-view non-propagating-cache

 

std::ranges::stride_view

Member functions

stride_view::stride_view (C++23)

stride_view::base (C++23)

stride_view::stride (C++23)

stride_view::begin (C++23)

stride_view::end (C++23)

stride_view::size (C++23)

Deduction guides

Iterator

Member functions

stride_view::iterator::iterator (C++23)

stride_view::iterator::base (C++23)

stride_view::iterator::operator* (C++23)

stride_view::iterator::operator[] (C++23)

stride_view::iterator::operator++ stride_view::iterator::operator++(int) stride_view::iterator::operator-- stride_view::iterator::operator--(int) stride_view::iterator::operator+= stride_view::iterator::operator-= (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

Non-member functions

operator==(std::default_sentinel_t) operator==(stride_view::iterator) operator<(stride_view::iterator) operator>(stride_view::iterator) operator<=(stride_view::iterator) operator>=(stride_view::iterator) operator<=>(stride_view::iterator) (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

operator+(stride_view::iterator) operator-(stride_view::iterator) (C++23)(C++23)

iter_move(stride_view::iterator) (C++23)

iter_swap(stride_view::iterator) (C++23)

 

Defined in header <ranges>
template< ranges::input_range V >     requires ranges::view<V> class stride_view :     public ranges::view_interface<stride_view<V>>	(1)	(since C++23)
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, ranges::range_difference_t<R> n );		(since C++23)
template< class DifferenceType > constexpr /*range adaptor closure*/ stride( DifferenceType&& n );		(since C++23)
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.

Data members

Typical implementations of stride_view hold only two non-static data members:

• the underlying view of type V (shown here as base_ for exposition only),
• the size object (the "stride") of type ranges::range_difference_t<V> (shown here as stride_ for exposition only).

Member functions

(constructor) (C++23)	constructs a stride_view (public member function)
stride (C++23)	returns the stored stride value (public member function)
base (C++23)	returns a copy of the underlying (adapted) view (public member function)
begin (C++23)	returns an iterator to the beginning (public member function)
end (C++23)	returns an iterator or a sentinel to the end (public member function)
size (C++23)	returns the number of elements. Provided only if the underlying (adapted) range satisfies sized_range. (public member function)
Inherited from std::ranges::view_interface
empty (C++20)	returns whether the derived view is empty. Provided if it satisfies sized_range or forward_range. (public member function of std::ranges::view_interface<D>)
cbegin (C++23)	returns a constant iterator to the beginning of the range. (public member function of std::ranges::view_interface<D>)
cend (C++23)	returns a sentinel for the constant iterator of the range. (public member function of std::ranges::view_interface<D>)
operator bool (C++20)	returns whether the derived view is not empty. Provided if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>)
front (C++20)	returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
back (C++20)	returns the last element in the derived view. Provided if it satisfies bidirectional_range and common_range. (public member function of std::ranges::view_interface<D>)
operator[] (C++20)	returns the nth element in the derived view. Provided if it satisfies random_access_range. (public member function of std::ranges::view_interface<D>)

Nested classes

iterator (C++23)

the iterator type (exposition-only member class template*)

Helper templates

template< class V > inline constexpr bool ranges::enable_borrowed_range<stride_view<V>> =     ranges::enable_borrowed_range<V>;		(since C++23)

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	Comment
__cpp_lib_ranges_stride	202207L	(C++23)	std::ranges::stride_view

Example

A link to test: Compiler Explorer.

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