std::rotate_copy

Defined in header <algorithm>

template< class ForwardIt, class OutputIt >
OutputIt rotate_copy( ForwardIt first, ForwardIt n_first,
                      ForwardIt last, OutputIt d_first );

Copies the elements from the range [first, last), to another range beginning at d_first in such a way, that the element n_first becomes the first element of the new range and n_first - 1 becomes the last element.

Parameters

first, last	-	the range of elements to copy
n_first	-	an iterator to an element in `[first, last)` that should appear at the beginning of the new range
d_first	-	beginning of the destination range
Type requirements
- `ForwardIt` must meet the requirements of `ForwardIterator`.
- `OutputIt` must meet the requirements of `OutputIterator`.

Return value

Output iterator to the element past the last element copied.

Possible implementation

template<class ForwardIt, class OutputIt>
OutputIt rotate_copy(ForwardIt first, ForwardIt n_first,
                           ForwardIt last, OutputIt d_first)
{
    d_first = std::copy(n_first, last, d_first);
    return std::copy(first, n_first, d_first);
}

Example

#include <algorithm>
#include <vector>
#include <iostream>
  
int main()
{
    std::vector<int> src = {1, 2, 3, 4, 5}; 
    auto pivot = std::find(src.begin(), src.end(), 3); 
    std::vector<int> dest(src.size());                                          
  
    std::rotate_copy(src.begin(), pivot, src.end(), dest.begin());
  
    for (const auto &i : dest) {
        std::cout << i << ' ';
    }   
    std::cout << '\n';
}

Output:

1	`3 4 5 1 2`

Complexity

linear in the distance between first and last.

rotate	rotates the order of elements in a range (function template)
std::experimental::parallel::rotate_copy (parallelism TS)	parallelized version of `std::rotate_copy` (function template)