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# std::swap_ranges

From cppreference.com
< cpp‎ | algorithm

Defined in header `<algorithm>` |  |
template< class ForwardIt1, class ForwardIt2 > ForwardIt2 swap_ranges( ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2 ) |  |

Exchanges elements between range `[first1, last1)` and another range starting at `first2`.

### [edit] Parameters

first1, last1 | - | the first range of elements to swap
first2 | - | beginning of the second range of elements to swap
Type requirements
- `ForwardIt1, ForwardIt2` must meet the requirements of `ForwardIterator`.
- The types of dereferenced `ForwardIt1` and `ForwardIt2` must meet the requirements of `Swappable`

### [edit] Return value

Iterator to the element past the last element exchanged in the range beginning with `first2`.

### [edit] Possible implementation

    template<class ForwardIt1, class ForwardIt2>
    ForwardIt2 swap_ranges(ForwardIt1 first1,
                                 ForwardIt1 last1,
                                 ForwardIt2 first2)
    {
        while (first1 != last1) {
            std::iter_swap(first1++, first2++);
        }
        return first2;
    }

### [edit] Example

Demonstrates swapping of subranges from different containers

Run this code

    #include <algorithm>
    #include <list>
    #include <vector>
    #include <iostream>
    int main()
    {
        std::vector<int> v = {1, 2, 3, 4, 5};
        std::list<int> l = {-1, -2, -3, -4, -5};

        std::swap_ranges(v.begin(), v.begin()+3, l.begin());

        for(int n : v)
           std::cout << n << ' ';
        std::cout << '\n';
        for(int n : l)
           std::cout << n << ' ';
        std::cout << '\n';
    }

Output:

    -1 -2 -3 4 5
    1 2 3 -4 -5

### [edit] Complexity

linear in the distance between `first` and `last`

### [edit] See also

iter_swap | swaps the elements pointed to by two iterators (function template) [edit]
swap | swaps the values of two objects (function template) [edit]

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