std::rotate_copy (3) - Linux Manuals

std::rotate_copy: std::rotate_copy

NAME

std::rotate_copy - std::rotate_copy

Synopsis

Defined in header <algorithm>
template< class ForwardIt, class OutputIt >
OutputIt rotate_copy( ForwardIt first, ForwardIt n_first, (until C++20)
ForwardIt last, OutputIt d_first );
template< class ForwardIt, class OutputIt >
constexpr OutputIt rotate_copy( ForwardIt first, ForwardIt n_first, (1) (since C++20)
ForwardIt last, OutputIt d_first );
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2 >
ForwardIt2 rotate_copy( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 n_first, (2) (since C++17)
ForwardIt1 last, ForwardIt2 d_first );

1) 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.
2) Same as (1), but executed according to policy. This overload only participates in overload resolution if std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true

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
policy - the execution policy to use. See execution_policy for details.

Type requirements

-
ForwardIt, ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
-
OutputIt must meet the requirements of LegacyOutputIterator.

Return value

Output iterator to the element past the last element copied.

Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

* If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard_policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
* If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation

See also the implementations in libstdc++ and libc++.

  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

// Run this code

  #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:

  3 4 5 1 2

Complexity

linear in the distance between first and last