std::ranges::take_view<V>::end

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

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_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t   (C++23)	iterator_tconst_iterator_tsentinel_t (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
Factories
empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
Adaptors
ref_view views::all_tviews::all common_viewviews::common owning_view views::counted reverse_viewviews::reverse zip_viewviews::zip (C++23)(C++23) as_const_viewviews::as_const (C++23)(C++23) as_rvalue_viewviews::as_rvalue (C++23)(C++23)	take_viewviews::take take_while_viewviews::take_while drop_viewviews::drop drop_while_viewviews::drop_while zip_transform_viewviews::zip_transform (C++23)(C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)   cartesian_product_viewviews::cartesian_product (C++23)(C++23)	elements_viewviews::elements keys_viewviews::keys values_viewviews::values transform_viewviews::transform adjacent_viewviews::adjacent (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) stride_viewviews::stride (C++23)(C++23)	filter_viewviews::filter join_viewviews::join split_viewviews::split lazy_split_viewviews::lazy_split join_with_viewviews::join_with (C++23)(C++23) chunk_viewviews::chunk (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23)
Range adaptor objects
Range adaptor closure objects
Helper items
copyable-box	simple-view

 

std::ranges::take_view

Member functions

take_view::take_view (C++20)

take_view::base (C++20)

take_view::begin (C++20)

take_view::end (C++20)

take_view::size (C++20)

Deduction guides

Sentinel

take_view::sentinel::sentinel (C++20)

take_view::sentinel::base (C++20)

operator==(std::counted_iterator,take_view::sentinel) (C++20)

 

constexpr auto end() requires (!__SimpleView<V>);	(1)	(since C++20)
constexpr auto end() const requires ranges::range<const V>;	(2)	(since C++20)

Returns a sentinel or an iterator representing the end of the take_view. The end of the take_view is either one past the count-th element in the underlying range, or the end of the underlying range if the latter has less than count elements.

1) Returns a take_view::/*sentinel*/<false>, a std::default_sentinel_t, or a ranges::iterator_t<V>.

2) Returns a take_view::/*sentinel*/<true>, a std::default_sentinel_t, or a ranges::iterator_t<const V>.

Overload (1) does not participate in overload resolution if V is a simple view (that is, if V and const V are views with the same iterator and sentinel types).

Parameters

(none)

Return value

The result depends on the concepts satisfied by possible const-qualified underlying view type Base_, that is V (for overload (1)) or const V (for overload (2)).

Let base_ be the underlying view.

The underlying view satisfies ...		random_access_range
		yes	no
sized_range	yes	ranges::begin(base_) + ranges::range_difference_t<Base_>(this->size())	std::default_sentinel
	no	1) /*sentinel*/<false>{ranges::end(base_)} 2) /*sentinel*/<true>{ranges::end(base_)}

Example

Run this code

#include <list>
#include <ranges>
#include <iterator>
#include <iostream>
#include <type_traits>
 
int main() {
    const auto list1 = { 3, 1, 4, 1, 5 };
    const auto seq1 = list1 | std::views::take(4);
    static_assert(std::ranges::sized_range<decltype(seq1)> and
                  std::ranges::random_access_range<decltype(seq1)> and
                  std::is_same_v<decltype(seq1.end()), decltype(list1.end())>);
    for (auto it = seq1.begin(); it != seq1.end(); std::cout << *it++ << ' '){ }
    std::cout << '\n';
 
    std::list list2 = { 2, 7, 1, 8, 2 };
    const auto seq2 = list2 | std::views::take(4);
    static_assert(std::ranges::sized_range<decltype(seq2)> and
                  not std::ranges::random_access_range<decltype(seq2)> and
                  std::is_same_v<decltype(seq2.end()), std::default_sentinel_t>);
    for (auto it = seq2.begin(); it != std::default_sentinel; std::cout << *it++ << ' '){ }
    std::cout << '\n';
}

Output:

3 1 4 1
2 7 1 8

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
P2393R1	C++20	implicit conversions between signed and unsigned integer-class types might fail	made explicit

See also

begin (C++20)	returns an iterator to the beginning (public member function)
counted_iterator (C++20)	iterator adaptor that tracks the distance to the end of the range (class template)
operator== (C++20)	compares a sentinel with an iterator returned from take_view::begin (function)