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std::ranges::cartesian_product_view<First, Vs...>::end

constexpr iterator<false> end()
    requires ((!__simple_view<First> || ... || !__simple_view<Vs>) &&
        __cartesian_product_is_common<First, Vs...>);
 (1) (since C++23) 
constexpr iterator<true> end() const
    requires __cartesian_product_is_common<const First, const Vs...>;
 (2) (since C++23) 
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 otherwise;
  • __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 otherwise; 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

#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

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

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https://en.cppreference.com/w/cpp/ranges/cartesian_product_view/end