C++ <algorithm> - reverse_copy() Function

The C++ algorithm::reverse_copy function is used to copy all elements in the range [first, last) to the range starting at result in reverse order.

Syntax

template <class BidirectionalIterator, class OutputIterator>
  OutputIterator reverse_copy (BidirectionalIterator first,
                               BidirectionalIterator last, 
                               OutputIterator result);

Parameters

`first`	Specify initial position of the bidirectional iterator. The range used is [first,last).
`last`	Specify final position of the bidirectional iterator. The range used is [first,last).
`result`	Specify initial position of the output iterator where the result to be stored.

Return Value

Returns an output iterator pointing to the element that follows the last element copied in result sequence.

Time Complexity

Linear i.e, Θ(n).

Example:

In the example below, the algorithm::reverse_copy function is used to copy all elements of an array to a vector in reverse order.

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int main (){
  int arr[] = {10, 11, 12, 13, 14, 15};
  vector<int> vec(6);
  vector<int>::iterator it;

  //copy elements from array to vector in reverse order
  reverse_copy(arr, arr+6, vec.begin());

  cout<<"arr contains:";
  for(int i = 0; i < 6; ++i)
    cout<<" "<<arr[i];

  cout<<"\nvec contains:";
  for(it = vec.begin(); it != vec.end(); ++it)
    cout<<" "<<*it;

  return 0;
}

The output of the above code will be:

arr contains: 10 11 12 13 14 15
vec contains: 15 14 13 12 11 10

❮ C++ <algorithm> Library