std::swap_ranges

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.

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`

Return value

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

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;
}

Example

Demonstrates swapping of subranges from different containers.

#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

Complexity

linear in the distance between first and last.

iter_swap	swaps the elements pointed to by two iterators (function template)
swap	swaps the values of two objects (function template)
std::experimental::parallel::swap_ranges (parallelism TS)	parallelized version of `std::swap_ranges` (function template)