# std::ranges::adjacent_transform_view<V,F,N>::begin

From cppreference.com
< cpp‎ | ranges‎ | adjacent transform view

constexpr auto begin(); | (1) | (since C++23)
constexpr auto begin() const requires ranges::range<const InnerView> && std::regular_invocable<const F&, __REPEAT(ranges::range_reference_t<const V>, N)...>; | (2) | (since C++23)

Returns an iterator to the first element of the `adjacent_transform_view`.

Let `inner_` be the underlying ranges::adjacent_view.

1) Equivalent to return /*iterator*/<false>(*this, inner_.begin());.
2) Equivalent to return /*iterator*/<true>(*this, inner_.begin());.

### Parameters

(none)

### Return value

Iterator to the first element.

### Example

A link to test: Compiler Explorer/g++-13

Run this code

    #include <ranges>

    int main()
    {
        auto sum = [](auto... args) { return (... + args); };

        constexpr auto view = std::views::iota(13, 1337)
                            | std::views::adjacent_transform<3>(sum);

        static_assert(*view.begin() == 42 and 42 == 13 + 14 + 15);
    }

### See also

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

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/ranges/adjacent_transform_view/begin&oldid=144434"