Home Original page

std::ranges::drop_view<V>::size - cppreference.com

From cppreference.com

constexpr auto size() requires ranges::sized_range<V>;

 (1) (since C++20)

constexpr auto size() const requires ranges::sized_range<const V>;

 (2) (since C++20)

Let base_ be the underlying view, count_ be the stored count (the number passed to the constructor, or 0 if *this is default constructed). Equivalent to

const auto s = ranges::size(base_);
const auto c = static_cast<decltype(s)>(count_);
return s < c ? 0 : s - c;

Return value

The number of elements.

Example

#include <array>
#include <ranges>

int main()
{
    constexpr std::array a{42, 43, 44};
    static_assert
    (
        std::ranges::drop_view{std::views::all(a), 0}.size() == 3 &&
        std::ranges::drop_view{std::views::all(a), 1}.size() == 2 &&
        std::ranges::drop_view{std::views::all(a), 2}.size() == 1 &&
        std::ranges::drop_view{std::views::all(a), 3}.size() == 0 &&
        std::ranges::drop_view{std::views::all(a), 4}.size() == 0
    );
}

See also

returns an integer equal to the size of a range
(customization point object)[edit]
returns a signed integer equal to the size of a range
(customization point object)[edit]