Answer to Question 30-1

  void removeAll(const int x, List& L)
  {
    if(L != NULL)
    {
      if(L-> == x)
      {
        List p = L;
        L = L->tail;
        delete p;
        removeAll(x, L);
      }
      else
      {
        removeAll(x, L->tail))
      }
    }
  }