std::ranges::slide_view<V>::begin
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>( Otherwise, equivalent to:
ranges::begin(base_),
ranges::next(ranges::begin(base_), n_ - 1, ranges::end(base_)),
n_
);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
#include <iostream>
#include <ranges>
#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 << ' ';
std::cout << '\n';
}Output:
∀x ∃y
See also
|
(C++23) | returns an iterator or a sentinel to the end (public member function) |
|
(C++23) | compares a sentinel with an iterator returned from slide_view::begin (function) |
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