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std::ranges...erface::size(3) C++ Standard Libarystd::ranges...erface::size(3) NAME std::ranges::view_interface::size - std::ranges::view_interface::size Synopsis 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 size() member function obtains the size of the range by calculating the difference between the sentinel and the beginning iterator. 1) Let derived be static_cast<D&>(*this). Equivalent to return /*to-unsigned-like*/(ranges::end(derived) - ranges::begin(de- rived));, where the exposition-only function template to-unsigned-like performs the ex- plicit 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) Return value The difference between the sentinel and the beginning iterator of the value of the derived type, converted to its corresponding unsigned type. 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_sen- tinel_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 retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 3646 C++20 the default implementations of size they return unsigned functions returned a signed type type See also size ssize returns the size of a container or array (C++17) (function template) (C++20) 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) http://cppreference.com 2024.06.10 std::ranges...erface::size(3)
NAME | Synopsis | Parameters | Return value | Notes | See also
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