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

using namespace std;

void vector_out(vector<double> v)
{
  copy(v.begin(),v.end(), // from
       ostream_iterator<double>(cout," ")); // to 
  cout<<endl;
}

int main()
{
  vector<double> v,w;
  vector<double>::iterator it;
  v.push_back(1.0);v.push_back(2.0); v.push_back(3.0);
  w.push_back(21.0);w.push_back(22.0); w.push_back(23.0);
  cout<<" v = ";
  vector_out(v);
  cout<<" w = ";    
  vector_out(w);
  cout<<"swapping\n";
  swap(v,w);
  cout<<" v = ";
  vector_out(v);
  cout<<" w = ";
  vector_out(w);
}