std::ranges::drop_view<V>:: size

Returns the number of elements.

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;

Parameters

(none)

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);
    static_assert(std::ranges::drop_view{std::views::all(a), 1}.size() == 2);
    static_assert(std::ranges::drop_view{std::views::all(a), 2}.size() == 1);
    static_assert(std::ranges::drop_view{std::views::all(a), 3}.size() == 0);
    static_assert(std::ranges::drop_view{std::views::all(a), 4}.size() == 0);
}

See also