#include <iostream.h>

class ListElem
{
public:
   int      value;      // Integer
   ListElem *next;      // Pointer used to make link    
};


void Print(ListElem *head)
{
   ListElem *p;

   p = head;             // Very important: start at first element

   cout << "List ==> ";
   while ( p != NULL )
   {
      cout << p->value << "  ";  // Access value stored in list element  
      p = p->next;               // Visit next element in list
   }
   cout << "\n\n";
}

/* -----------------------------------------------------------
   InsertAtHead: insert elem at start of linked list

   Question: what would happen if we pass "head" by value ?
   ----------------------------------------------------------- */
void InsertAtHead(ListElem * & head, ListElem * elem)
{
   elem->next = head;    // Make new list element points   
                         // to the start of "old list"   

   head = elem;          // Make "head" points to 
                         // the **new** starting object
}

int main(int argc, char *argv[])
{
   ListElem *head, *p;
   void Print(ListElem *);
   void InsertAtHead(ListElem * &, ListElem *);

   head = NULL;
   Print(head);

   p = new ListElem;
   p->value = 1500;
   InsertAtHead(head, p);
   Print(head);
   
   p = new ListElem;
   p->value = 2500;
   InsertAtHead(head, p);
   Print(head);
   
   p = new ListElem;
   p->value = 3500;
   InsertAtHead(head, p);
   Print(head);
}