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std::ranges...t_view::end(3)   C++ Standard Libary  std::ranges...t_view::end(3)

NAME
     std::ranges::cartesian_product_view::end	-   std::ranges::cartesian_prod-
     uct_view::end

Synopsis
	constexpr iterator<false> end()

	    requires ((!__simple_view<First> || ... ||	!__simple_view<Vs>)  (1)
     (since C++23)
	&&

		__cartesian_product_is_common<First, Vs...>);
	constexpr iterator<true> end() const
	    requires  __cartesian_product_is_common<const  First, const      (2)
     (since C++23)
	Vs...>;
	constexpr std::default_sentinel_t end() const  noexcept;	     (3)
     (since C++23)

	Returns an iterator or a sentinel representing the end of the
	cartesian_product_view.

	Let bases_ be the underlying tuple of views.

	1,2) Let:
	  *  __is_const be true for the const-qualified overload, and false oth-
     erwise;
	  * __is_empty be true if the expression ranges::empty(rng) is true  for
     any rng
	    among  the	underlying  ranges except the first one and false other-
     wise; and
	  * __begin_or_first_end(rng) be expression-equivalent to __is_empty ?
	    ranges::begin(rng) : __cartesian_common_arg_end(rng) if rng  is  the
     first
	    underlying range and ranges::begin(rng) otherwise.

	Equivalent to:

      auto check = [](auto& rng) { return __begin_or_first_end(rng); };
      return iterator<__is_const>(__tuple_transform(check, bases_));

	3) Equivalent to: return std::default_sentinel;.

Parameters
	(none)

Return value
	An  iterator  to  the  element following the last element, or a sentinel
     which compares
	equal to the end iterator.

Example
     // Run this code

      #include <array>
      #include <format>
      #include <iostream>
      #include <ranges>
      #include <string_view>
      #include <tuple>
      using namespace std::literals;

      int main()
      {
	  constexpr  auto  a  =  std::array{  "bool"sv,  "goto"sv,   "extern"sv,
     "long"sv }; /*
					     ^		^	     ^	       ^
     */
	  constexpr auto  v  =	std::ranges::cartesian_product_view(a[0],  a[1],
     a[2], a[3]);

	  constexpr std::tuple<char const&,
			       char const&,
			       char const&,
			       char const&> last{*(v.end() - 1)};

	  std::cout << std::format("{}{}{}{}{}",
				   std::get<0>(last),
				   std::get<1>(last),
				   std::get<2>(last),
				   std::get<3>(last), '\n');
      }

Output:
      long

See also
	begin	    returns an iterator to the beginning
	(C++23)     (public member function)
	ranges::end returns a sentinel indicating the end of a range
	(C++20)     (customization point object)

http://cppreference.com 	   2024.06.10	    std::ranges...t_view::end(3)
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