27 Algorithms library [algorithms]

27.7 Mutating sequence operations [alg.modifying.operations]

27.7.3 Swap [alg.swap]

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template<class ForwardIterator1, class ForwardIterator2> constexpr ForwardIterator2 swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2); // freestanding template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2> ForwardIterator2 swap_ranges(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2); template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2> requires indirectly_swappable<I1, I2> constexpr ranges::swap_ranges_result<I1, I2> ranges::swap_ranges(I1 first1, S1 last1, I2 first2, S2 last2); template<input_range R1, input_range R2> requires indirectly_swappable<iterator_t<R1>, iterator_t<R2>> constexpr ranges::swap_ranges_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>> ranges::swap_ranges(R1&& r1, R2&& r2);
1
#
Let:
  • (1.1)
    last2 be first2 + (last1 - first1) for the overloads with no parameter named last2;
  • (1.2)
    M be min(last1 - first1,  last2 - first2).
2
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Preconditions: The two ranges [first1, last1) and [first2, last2) do not overlap.
For the overloads in namespace std, *(first1 + n) is swappable with ([swappable.requirements]) *(first2 + n).
3
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Effects: For each non-negative integer performs:
  • (3.1)
    swap(*(first1 + n), *(first2 + n)) for the overloads in namespace std;
  • (3.2)
    ranges​::​iter_swap(first1 + n, first2 + n) for the overloads in namespace ranges.
4
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Returns:
  • (4.1)
    last2 for the overloads in namespace std.
  • (4.2)
    {first1 + M, first2 + M} for the overloads in namespace ranges.
5
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Complexity: Exactly M swaps.
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template<class ForwardIterator1, class ForwardIterator2> constexpr void iter_swap(ForwardIterator1 a, ForwardIterator2 b);
6
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Preconditions: a and b are dereferenceable.
*a is swappable with ([swappable.requirements]) *b.
7
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Effects: As if by swap(*a, *b).