# std::ranges::slide_view<V>::begin

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< cpp‎ | ranges‎ | slide view

constexpr auto begin() requires (!(__simple_view<V> && __slide_caches_nothing<const V>)); | (1) | (since C++23)
constexpr auto begin() const requires __slide_caches_nothing<const V>; | (2) | (since C++23)

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

1) If V models `__slide_caches_first`, equivalent to:

return iterator<false>(
ranges::begin(base_),
ranges::next(ranges::begin(base_), n_ - 1, ranges::end(base_)),
n_
);

Otherwise, equivalent to: return iterator<false>(ranges::begin(base_), n_);.
If V models `__slide_caches_first` this function caches the result within the `slide_view::cached_begin_` for use on subsequent calls. This is necessary to provide the amortized constant-time complexity required by the `range`.
2) Equivalent to: return iterator<true>(ranges::begin(base_), n_);.

### Parameters

(none)

### Return value

An iterator to the first element of `slide_view`, which points to the `n_`-sized subrange of the possibly const-qualified underlying view type – V for overload (1) or const V for overload (2).

### Example

A link to test: Compiler Explorer

Run this code

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

    int main()
    {
        static constexpr auto source = {"∀x"sv, "∃y"sv, "ε"sv, "δ"sv};
        auto view {std::ranges::slide_view(source, 2)};
        const auto subrange {*(view.begin())};
        for (std::string_view const s: subrange)
            std::cout << s << ' ';
    }

Output:

    ∀x ∃y

### See also

end (C++23) | returns an iterator or a sentinel to the end (public member function)
operator== (C++23) | compares a sentinel with an iterator returned from `slide_view::begin` (function)

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