std::ranges::take_view<V>::end
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C++
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Concepts library (C++20)
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Execution control library (C++26)
Ranges library
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++26)(C++26)
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(C++23)(C++23)
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(C++23)
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(C++23)
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(C++23)(C++23)
(C++23)(C++23)
(C++23)
std::ranges::take_view
take_view::end
(C++26)
Member functions
Non-member functions
constexpr auto end() requires (!/*simple-view*/<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 countth 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).
[edit] Parameters
(none)
[edit] Return value
The result depends on the concepts satisfied by possibly const-qualified underlying view type Base, that is V for (1) or const V for (2).
Let base_ be the underlying view.
| The underlying view type 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_)}
| ||
[edit] Example
Run this code
#include <iostream> #include <iterator> #include <list> #include <ranges> #include <type_traits> namespace ranges = std::ranges; namespace views = std::views; int main() { const auto list1 = {3, 1, 4, 1, 5}; const auto seq1{list1 | views::take (4)}; static_assert(ranges::sized_range <decltype(seq1)> and 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(); ++it) std::cout << *it << ' '; std::cout << '\n'; std::list list2{2, 7, 1, 8, 2}; const auto seq2{list2 | views::take (4)}; static_assert(ranges::sized_range <decltype(seq2)> and not 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 ; ++it) std::cout << *it << ' '; std::cout << '\n'; }
Output:
3 1 4 1 2 7 1 8
[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 |
|---|---|---|---|
| P2393R1 | C++20 | implicit conversions between signed and unsigned integer-class types might fail | made explicit |