using namespace std;
#include <iostream>
#include "struct_stack.h"


static boolean emptyp (stack s) {
  return (boolean) (s == NULL);
}

void init(stack & s) {
  s = NULL;
}

retval top (int &n,stack s) {
  if (emptyp(s))
    return FAIL;
  n=s -> val;
  return OK;
}

retval push (int n,stack & s) {
  nodo * np = new nodo;
  if (np==NULL) return FAIL;
  np -> val = n;
  np -> next = s;
  s = np;
  return OK;
}

retval pop (stack & s) {
  if (emptyp(s))
    return FAIL;
  nodo *first = s;
  s = s -> next;
  delete first; 	/* liberare la memoria: cancella
			   l'oggetto puntato da first*/
  return OK;
}

void print (stack s) 
{
  nodo *first = s;
  while (first!=NULL) {
    cout << first->val << " ";
    first = first -> next;
  }
  cout << endl;
}

void print_reverse (stack s) 
{
  nodo *first = s;
  if (first == NULL) return;
  else {
    print_reverse (first -> next);
    cout << first->val << " ";
  }
}