Figure 14.21  Iterative Function get_list
/*
 *  Forms a linked list of an input list of integers terminated by SENT
 */
list_node_t *
get_list(void)
{
      int data;
      list_node_t *ansp,
                  *to_fillp, /* pointer to last node in list whose
                                restp component is unfilled         */
                  *newp;     /* pointer to newly allocated node     */
 
      /* Builds first node, if there is one */
      scanf("%d", &data);
      if (data == SENT) {
            ansp = NULL;
      } else {
            ansp = (list_node_t *)malloc(sizeof (list_node_t));
            ansp->digit = data;
            to_fillp = ansp;

            /* Continues building list by creating a node on each
iteration and storing its pointer in the restp component of the
node accessed through to_fillp */
            for  (scanf("%d", &data);
                  data != SENT;
                  scanf("%d", &data)) {
                newp = (list_node_t *)malloc(sizeof (list_node_t));
                newp->digit = data;
                to_fillp->restp = newp;
                to_fillp = newp;
            }

            /* Stores NULL in final node's restp component */
            to_fillp->restp = NULL;
      }
      return (ansp);
}