C++ Tutorial/STL Algorithms Non modifying sequence operations/copy backward

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copy_backward, merge, unique and reverse.

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
   const int SIZE = 5;
   int a1[ SIZE ] = { 1, 3, 5, 7, 9 };
   int a2[ SIZE ] = { 2, 4, 5, 7, 9 };
   vector< int > v1( a1, a1 + SIZE );
   vector< int > v2( a2, a2 + SIZE );
   vector< int > results( v1.size() );
   copy_backward( v1.begin(), v1.end(), results.end() );
   
   vector< int > results2( v1.size() + v2.size() );
   merge( v1.begin(), v1.end(), v2.begin(), v2.end(),results2.begin() );
   
   vector< int >::iterator endLocation;
   endLocation = unique( results2.begin(), results2.end() );
   reverse( v1.begin(), v1.end() );
   cout << endl;
   return 0;
}

Use copy_backward to copy value from vector to a list

#include <algorithm>
#include <vector>
#include <list>
#include <iostream>
using namespace std;
int main (){
    list <int> l;
    for (int nCount = 0; nCount < 10; ++ nCount)
        l.push_back (nCount);
    list <int>::const_iterator li;
    for ( li = l.begin (); li != l.end (); ++ li )
        cout << *li << " ";
    vector <int> v (l.size () * 2);
    copy_backward ( l.begin (), l.end (), v.end () );
    vector <int>::const_iterator vi;
    for ( vi = v.begin (); vi != v.end (); ++ vi )
        cout << *vi << " ";
    return 0;
}

Use std::copy_backward to place elements in one vector into another vector in reverse order

#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

Use the copy_backward algorithms: Shift it right by 2 positions

#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
int main()
{
  string s("abcdefghihklmnopqrstuvwxyz");
  vector<char> vector1(s.begin(), s.end());
  copy_backward(vector1.begin(), vector1.end() - 2, vector1.end());
  vector<char>::iterator pos;
  for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
        cout << *pos << " ";
  }
  return 0;
}
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