std::ranges...erface::size(3)

✨ std::ranges::view_interface::size ✨

okay bestie, this is the C++ Standard Libary manual page for std::ranges::view_interface::size, and we’re gonna make it make sense. no cap. 🫶

🎀 NAME 🎀

std::ranges::view_interface::size — std::ranges::view_interface::size

🌸 Synopsis 🌸

here’s the exact signature energy, bestie — two overloads, both (since C++20), and yes the formatting is giving “manpage chic” 😭💅

          constexpr auto size() requires ranges::forward_range<D> &&

              std::sized_sentinel_for<ranges::sentinel_t<D>,
       (1) (since C++20)

                                      ranges::iterator_t<D>>;
          constexpr auto size() const requires ranges::forward_range<const
          D> &&
                                                                             (2)
       (since C++20)
              std::sized_sentinel_for<ranges::sentinel_t<const D>,

                                      ranges::iterator_t<const D>>;

the default implementation of the size() member function gets the size of the range by calculating the difference between the sentinel and the beginning iterator. iconic behavior, honestly. ✨

1. let derived be static_cast<D&>(*this). Equivalent to return /*to-unsigned-like*/(ranges::end(derived) - ranges::begin(derived));, where the exposition-only function template to-unsigned-like performs the explicit cast from the argument type to its corresponding unsigned type.
2. same as (1), except that derived is static_cast<const D&>(*this).

🫶 Parameters 🫶

(none) — literally none. no args, no stress. 😌

💖 Return value 💖

the difference between the sentinel and the beginning iterator of the value of the derived type, converted to its corresponding unsigned type. slay. 👑

🧚 Notes 🧚

following derived types may use the default implementation of size():

• std::ranges::drop_while_view

following types are derived from std::ranges::view_interface and do not declare their own size() member function, but they cannot use the default implementation, because their iterator and sentinel types never satisfy sized_sentinel_for:

• std::ranges::basic_istream_view
• std::ranges::filter_view
• std::ranges::join_view
• std::ranges::lazy_split_view
• std::ranges::split_view
• std::ranges::take_while_view

💀 Defect reports 💀

the following behavior-changing defect reports were applied retroactively to previously published C++ standards:

• LWG 3646 — applied to C++20; as published: the default implementations of size functions returned a signed type; correct behavior: they return unsigned type.

🔥 See also 🔥

• size (C++17) — returns the size of a container or array (function template)
• ssize (C++20) — returns the size of a container or array (function template)
• ranges::size (C++20) — returns an integer equal to the size of a range (customization point object)
• ranges::ssize (C++20) — returns a signed integer equal to the size of a range (customization point object)

source: http://cppreference.com · version/date: 2024.06.10 · page: std::ranges...erface::size(3) — bye bestie, go get that unsigned type 💅✨