//sample code to show declaration of iterators
// and also use of find function (in STL Algorithms)


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


// PrintCollection - from list class notes

template <typename Container>
void PrintCollection( const Container & c, ostream & out )
{
  if( c.empty( ) )
    out << "(empty)";
  else
    {
      // note the required keyword 
      typename Container::const_iterator itr = c.begin( );
      out << "[ " << *itr++;   // Print first item
      
      while( itr != c.end( ) )
	out << ", " << *itr++;
      out << " ]" << endl;
    }
}





template <typename T>
void Subtract (list <T> & L, const list<T> & E) {
  list<int>::const_iterator eItr = E.begin(); 
                  //E is const, so eItr must be const_iterator.

  for (;eItr != E.end(); ++eItr){

    //Algorithm version of find differs from class version.
    list<int>:: iterator found= find(L.begin(), L.end(), *eItr);

    while (found !=L.end()) {
      L.erase(found);
      found= find(L.begin(), L.end(), *eItr);
    } //end while
  }   //end for
}     //end function     


int main() {
  list<int> L1;
  list<int> L2;

  //put some stuff in the 2 lists
  for (int z= 1; z < 20; z+= 2)
    L1.push_back(z);

  cout << "List contents before subtraction" << endl;
  PrintCollection (L1, cout);


  for(int x=2; x < 14; x+=3)
    L2.push_back(x);

  cout << "Removing all occurrences from this list:" << endl;
  PrintCollection (L2, cout);

 Subtract(L1, L2);

 cout << "after subtraction" << endl;
  PrintCollection (L1, cout);

}