[range.subrange.general]

The subrange class template combines together an iterator and a sentinel into a single object that models the view concept.

Additionally, it models the sized_range concept when the final template parameter is subrange_kind::sized.

namespace std::ranges { template<class From, class To> concept convertible-to-non-slicing = // exposition only convertible_to<From, To> && !(is_pointer_v<decay_t<From>> && is_pointer_v<decay_t<To>> && not-same-as<remove_pointer_t<decay_t<From>>, remove_pointer_t<decay_t<To>>>); template<class T> concept pair-like = // exposition only !is_reference_v<T> && requires(T t) { typename tuple_size<T>::type; // ensures tuple_size<T> is complete requires derived_from<tuple_size<T>, integral_constant<size_t, 2>>; typename tuple_element_t<0, remove_const_t<T>>; typename tuple_element_t<1, remove_const_t<T>>; { get<0>(t) } -> convertible_to<const tuple_element_t<0, T>&>; { get<1>(t) } -> convertible_to<const tuple_element_t<1, T>&>; }; template<class T, class U, class V> concept pair-like-convertible-from = // exposition only !range<T> && pair-like<T> && constructible_from<T, U, V> && convertible-to-non-slicing<U, tuple_element_t<0, T>> && convertible_to<V, tuple_element_t<1, T>>; template<class T> concept iterator-sentinel-pair = // exposition only !range<T> && pair-like<T> && sentinel_for<tuple_element_t<1, T>, tuple_element_t<0, T>>; template<input_or_output_iterator I, sentinel_for S = I, subrange_kind K = sized_sentinel_for<S, I> ? subrange_kind::sized : subrange_kind::unsized> requires (K == subrange_kind::sized || !sized_sentinel_for<S, I>) class subrange : public view_interface<subrange<I, S, K>> { private: static constexpr bool StoreSize = // exposition only K == subrange_kind::sized && !sized_sentinel_for<S, I>; I begin_ = I(); // exposition only S end_ = S(); // exposition only make-unsigned-like-t<iter_difference_t> size_ = 0; // exposition only; present only // when StoreSize is true public: subrange() = default; constexpr subrange(convertible-to-non-slicing auto i, S s) requires (!StoreSize); constexpr subrange(convertible-to-non-slicing auto i, S s, make-unsigned-like-t<iter_difference_t> n) requires (K == subrange_kind::sized); template<not-same-as<subrange> R> requires borrowed_range<R> && convertible-to-non-slicing<iterator_t<R>, I> && convertible_to<sentinel_t<R>, S> constexpr subrange(R&& r) requires (!StoreSize || sized_range<R>); template<borrowed_range R> requires convertible-to-non-slicing<iterator_t<R>, I> && convertible_to<sentinel_t<R>, S> constexpr subrange(R&& r, make-unsigned-like-t<iter_difference_t> n) requires (K == subrange_kind::sized) : subrange{ranges::begin(r), ranges::end(r), n} {} template<not-same-as<subrange> PairLike> requires pair-like-convertible-from<PairLike, const I&, const S&> constexpr operator PairLike() const; constexpr I begin() const requires copyable; [[nodiscard]] constexpr I begin() requires (!copyable); constexpr S end() const; constexpr bool empty() const; constexpr make-unsigned-like-t<iter_difference_t> size() const requires (K == subrange_kind::sized); [[nodiscard]] constexpr subrange next(iter_difference_t n = 1) const & requires forward_iterator; [[nodiscard]] constexpr subrange next(iter_difference_t n = 1) &&; [[nodiscard]] constexpr subrange prev(iter_difference_t n = 1) const requires bidirectional_iterator; constexpr subrange& advance(iter_difference_t n); }; template<input_or_output_iterator I, sentinel_for S> subrange(I, S) -> subrange<I, S>; template<input_or_output_iterator I, sentinel_for S> subrange(I, S, make-unsigned-like-t<iter_difference_t>) -> subrange<I, S, subrange_kind::sized>; template<iterator-sentinel-pair P> subrange(P) -> subrange<tuple_element_t<0, P>, tuple_element_t<1, P>>; template<iterator-sentinel-pair P> subrange(P, make-unsigned-like-t<iter_difference_t<tuple_element_t<0, P>>>) -> subrange<tuple_element_t<0, P>, tuple_element_t<1, P>, subrange_kind::sized>; template<borrowed_range R> subrange(R&&) -> subrange<iterator_t<R>, sentinel_t<R>, (sized_range<R> || sized_sentinel_for<sentinel_t<R>, iterator_t<R>>) ? subrange_kind::sized : subrange_kind::unsized>; template<borrowed_range R> subrange(R&&, make-unsigned-like-t<range_difference_t<R>>) -> subrange<iterator_t<R>, sentinel_t<R>, subrange_kind::sized>; template<size_t N, class I, class S, subrange_kind K> requires (N < 2) constexpr auto get(const subrange<I, S, K>& r); template<size_t N, class I, class S, subrange_kind K> requires (N < 2) constexpr auto get(subrange<I, S, K>&& r); } namespace std { using ranges::get; }

24 Ranges library [ranges]

24.5 Range utilities [range.utility]

24.5.4 Sub-ranges [range.subrange]

24.5.4.1 General [range.subrange.general]