std::ranges::subrange<I,S,K>::size
From cppreference.com
constexpr /*make-unsigned-like-t*/<std::iter_difference_t<I>> size() const
requires (K == ranges::subrange_kind::sized);
|
(since C++20) | |
Obtains the number of elements in the subrange:
- If
StoreSizeistrue, returnssize_. - Otherwise, returns
to-unsigned-like(end_-begin_).
For the definition of /*make-unsigned-like-t*/, see make-unsigned-like-t .
Return value
As described above.
Example
Run this code
#include <functional>
#include <print>
#include <ranges>
#include <utility>
int main()
{
const auto v = {2, 2, 2, 7, 1, 1, 1, 1, 8, 2, 2, 2, 2, 2};
// the value type of views::chunk_by is the ranges::subrange
auto to_pair = [](auto sub) { return std::make_pair(sub[0], sub.size()); };
/* ^^^^ */
auto pairs = v | std::views::chunk_by(std::equal_to{})
| std::views::transform(to_pair);
std::println("{}", pairs bitor std::views::keys);
std::println("{}", pairs bitor std::views::values);
}
Output:
[2, 7, 1, 8, 2]
[3, 1, 4, 1, 5]
See also
checks whether the subrange is empty (public member function) | |
(C++17)(C++20) |
returns the size of a container or array (function template) |
(C++20) |
returns an integer equal to the size of a range (customization point object) |