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 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.


#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

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

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.