std::ranges::take_view::end(3)

NAME
std::ranges::take_view::end - std::ranges::take_view::end

Synopsis
   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 random_access_range
   view satisfies
         ... yes no
                   ranges::begin(base_) +
               yes std::default_sentinel
   sized_range ranges::range_difference_t<Base_>(this->size())
               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 made explicit
                      integer-class types might fail

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