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std::ranges::drop_view::size(3) C++ Standard Libary std::ranges::drop_view::size(3)


std::ranges::drop_view::size - std::ranges::drop_view::size


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)

Returns the number of elements.

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

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.


// Run this code

#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

ranges::size returns an integer equal to the size of a range
(C++20) (customization point object)
ranges::ssize returns a signed integer equal to the size of a range
(C++20) (customization point object)