Use std::copy_backward to place elements in one vector into another vector in reverse order : copy_backward « STL Algorithms Non modifying sequence operations « C++ Tutorial

1. C++ Tutorial
2. STL Algorithms Non modifying sequence operations
3. copy_backward

#include <iostream>
using std::cout;
using std::endl;

#include <algorithm>
#include <vector>
#include <iterator>

int main()
{
   int a1[ 5 ] = { 1, 3, 5, 7, 9 };
   int a2[ 5 ] = { 2, 4, 5, 7, 9 };
   
   std::vector< int > v1( a1, a1 + 5 );
   std::vector< int > v2( a2, a2 + 5 );
   
   std::ostream_iterator< int > output( cout, " " );

   std::copy( v1.begin(), v1.end(), output ); // display vector output
   std::copy( v2.begin(), v2.end(), output ); // display vector output

   std::vector< int > results( v1.size() );

   // place elements of v1 into results in reverse order
   std::copy_backward( v1.begin(), v1.end(), results.end() );
   cout << "\n\nAfter copy_backward, results contains: ";
   std::copy( results.begin(), results.end(), output );
   
   cout << endl;
   return 0;
}

1 3 5 7 9 2 4 5 7 9

After copy_backward, results contains: 1 3 5 7 9