NAME¶

std::ranges::cartesian_product_view::begin - std::ranges::cartesian_product_view::begin

Synopsis¶

constexpr iterator<false> begin() (1) (since C++23)
requires (!__simple_view<First> || ... || !__simple_view<Vs>);
constexpr iterator<true> begin() const
requires (ranges::range<const First> && ... && (2) (since C++23)
ranges::range<const Vs>);

Returns an iterator to the first element of the cartesian_product_view.

Let bases_ be the tuple of underlying views.

1) Equivalent to return /*iterator*/<false>(__tuple_transform(ranges::begin,
bases_));.
2) Equivalent to return /*iterator*/<true>(__tuple_transform(ranges::begin,
bases_));.

Parameters¶

(none)

Return value¶

An iterator to the first element.

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{"Curiously"sv, "Recurring"sv, "Template"sv, "Pattern"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&> first{*v.begin()};

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

Output:¶

CRTP

See also¶

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