Std::reverse_copy (3) Linux Manual Page

std::reverse_copy – std::reverse_copy

Synopsis

Defined in header<algorithm>

    template <class BidirIt, class OutputIt>
    (until C++ 20)

        OutputIt reverse_copy(BidirIt first, BidirIt last, OutputIt d_first);

template <class BidirIt, class OutputIt>
(1)(since C++ 20)

    constexpr OutputIt reverse_copy(BidirIt first, BidirIt last, OutputIt d_first);

template <class ExecutionPolicy, class BidirIt, class ForwardIt>
(2)(since C++ 17)

    ForwardIt reverse_copy(ExecutionPolicy &&policy, BidirIt first, BidirIt last, ForwardIt d_first);
1) Copies the elements from the range [first, last) to another range beginning at d_first in such a way that the elements in the new range are in reverse order.

Behaves as if by executing the assignment *(d_first + (last - first) - 1 - i) = *(first + i) once for each non-negative i < (last - first)

If the source and destination ranges (that is, [first, last) and [d_first, d_first+(last-first)) respectively) overlap, the behavior is undefined.

2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true

Parameters

first, last – the range of elements to copy
d_first – the beginning of the destination range

Type requirements

–
BidirIt must meet the requirements of LegacyBidirectionalIterator.
–
OutputIt must meet the requirements of LegacyOutputIterator.
–
ForwardIt must meet the requirements of LegacyForwardIterator.

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 BidirIt, class OutputIt>
  OutputIt reverse_copy(BidirIt first, BidirIt last, OutputIt d_first)
  {
      while (first != last) {
          *(d_first++) = *(–last);
      }
      return d_first;
  }

Example

// Run this code

#include <vector>

#include <iostream>

#include <algorithm>
int main()

{
    std::vector<int> v({1, 2, 3});
    for (const auto &value : v) {
        std::cout << value << " ";
    }
    std::cout << '\n';
    std::vector<int> destination(3);
    std::reverse_copy(std::begin(v), std::end(v), std::begin(destination));
    for (const auto &value : destination) {
        std::cout << value << " ";
    }
    std::cout << '\n';
}

Output:

1 2 3
3 2 1

Complexity

Linear in the distance between first and last

std::reverse_copy (3) Linux Manual Page