constexpr auto size() requires ranges::forward_range<D> &&
std::sized_sentinel_for<ranges::sentinel_t<D>,
ranges::iterator_t<D>>;
| (1) | (since C++20) |
constexpr auto size() const requires ranges::forward_range<const D> &&
std::sized_sentinel_for<ranges::sentinel_t<const D>,
ranges::iterator_t<const D>>;
| (2) | (since C++20) |
The default implementation of size() member function obtains the size of the range by calculating the difference between the sentinel and the beginning iterator.
derived be static_cast<D&>(*this). Equivalent to return ranges::end(derived) - ranges::begin(derived);.derived is static_cast<const D&>(*this).(none).
The difference between the sentinel and the beginning iterator of the value of the derived type.
Following derived types may use the default implementation of size():
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 |
(C++17)(C++20) | returns the size of a container or array (function template) |
|
(C++20) | returns an integer equal to the size of a range (customization point object) |
|
(C++20) | returns a signed integer equal to the size of a range (customization point object) |
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