25 Algorithms library [algorithms]

25.7 Mutating sequence operations [alg.modifying.operations]

25.7.10 Reverse [alg.reverse]

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template<class BidirectionalIterator> constexpr void reverse(BidirectionalIterator first, BidirectionalIterator last); template<class ExecutionPolicy, class BidirectionalIterator> void reverse(ExecutionPolicy&& exec, BidirectionalIterator first, BidirectionalIterator last); template<bidirectional_­iterator I, sentinel_­for<I> S> requires permutable<I> constexpr I ranges::reverse(I first, S last); template<bidirectional_­range R> requires permutable<iterator_t<R>> constexpr borrowed_iterator_t<R> ranges::reverse(R&& r);
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Preconditions: For the overloads in namespace std, BidirectionalIterator meets the Cpp17ValueSwappable requirements ([swappable.requirements]).
2
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Effects: For each non-negative integer i < (last - first) / 2, applies std​::​iter_­swap, or ranges​::​​iter_­swap for the overloads in namespace ranges, to all pairs of iterators first + i, (last - i) - 1.
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Returns: last for the overloads in namespace ranges.
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Complexity: Exactly (last - first)/2 swaps.
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template<class BidirectionalIterator, class OutputIterator> constexpr OutputIterator reverse_copy(BidirectionalIterator first, BidirectionalIterator last, OutputIterator result); template<class ExecutionPolicy, class BidirectionalIterator, class ForwardIterator> ForwardIterator reverse_copy(ExecutionPolicy&& exec, BidirectionalIterator first, BidirectionalIterator last, ForwardIterator result); template<bidirectional_­iterator I, sentinel_­for<I> S, weakly_­incrementable O> requires indirectly_­copyable<I, O> constexpr ranges::reverse_copy_result<I, O> ranges::reverse_copy(I first, S last, O result); template<bidirectional_­range R, weakly_­incrementable O> requires indirectly_­copyable<iterator_t<R>, O> constexpr ranges::reverse_copy_result<borrowed_iterator_t<R>, O> ranges::reverse_copy(R&& r, O result);
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Let N be last - first.
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Preconditions: The ranges [first, last) and [result, result + N) do not overlap.
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Effects: Copies the range [first, last) to the range [result, result + N) such that for every non-negative integer i < N the following assignment takes place: *(result + N - 1 - i) = *(first + i).
8
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Returns:
  • (8.1)
    result + N for the overloads in namespace std.
  • (8.2)
    {last, result + N} for the overloads in namespace ranges.
9
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Complexity: Exactly N assignments.