std::ranges::take_view::begin(3)

NAME
std::ranges::take_view::begin - std::ranges::take_view::begin

Synopsis
   constexpr auto begin() requires (!__SimpleView<V>); (1) (since C++20)
   constexpr auto begin() const requires ranges::range<const V>; (2) (since C++20)
   Returns an iterator to the first element of the take_view.
   1) Returns a std::counted_iterator or a ranges::iterator_t<V>.
   2) Returns a std::counted_iterator 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 possibly const-qualified underlying
   view type Base_, which is V (for overload (1)) or const V (for overload (2)).
   Let base_ be the underlying view, count_ be the number passed to the constructor (0
   if default initialized).
   The underlying random_access_range
   view satisfies
         ... yes no
                        std::counted_iterator(ranges::begin(base_),
               yes ranges::begin(base_)
   sized_range
                        ranges::range_difference_t<Base_>(this->size()))
               no std::counted_iterator(ranges::begin(base_), count_)

Example
// Run this code
 #include <concepts>
 #include <forward_list>
 #include <iostream>
 #include <ranges>
 #include <string_view>
 #include <type_traits>
 using namespace std::literals;
 int main()
 {
     {
         static constexpr auto v = {"∀x"sv, "∃y"sv, "ε"sv, "δ"sv};
         auto view = std::ranges::take_view(v, 8);
         auto iter = view.begin();
         std::cout << *iter << '\n';
         static_assert(
             std::ranges::sized_range<decltype(v)> and
             std::ranges::random_access_range<decltype(v)> and
             std::is_same_v<decltype(iter), decltype(std::ranges::begin(v))>
         );
     }
     {
         std::forward_list v = {"Ax"sv, "Ey"sv, "p"sv, "q"sv};
         auto view = std::ranges::take_view(v, 8);
         auto iter = view.begin();
         std::cout << *iter << '\n';
         static_assert(
             not std::ranges::sized_range<decltype(v)> and
             not std::ranges::random_access_range<decltype(v)> and
             std::is_same_v<decltype(iter),
                 std::counted_iterator<
                     std::forward_list<std::string_view>::iterator>>
         );
     }
 }

Output:
 ∀x
 Ax
   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
   end returns an iterator or a sentinel to the end
   (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)