/**************************************************************************/
 /* LAB52.C: Recursion and Linked Lists                                    */
 #include <stdio.h>
 #define LISTSIZE 10

 typedef struct node_tag {
	 int             number;
	 struct node_tag *next;
 }node_type;
 /***********************    function build_list    *************************/
 /*  Preconditions: none                                                    */
 /*  Postconditions: List points to a linked list of integers               */
 /*                  If insufficient memory exists the function returns NULL*/
 /*  List values are read from the file list.dat and added to end of list   */
 node_type *build_list()  {
 FILE  *indatpt;        /* file pointer variable for input data file         */
 node_type *p,         /* p is the pointer to the first node in the list    */
	   *q;         /* q points to each node as it is created            */
 int i;

 /*  Open input file     */
 if ((indatpt = fopen("list.dat", "r")) == NULL)  {
    printf("Error in opening list.dat.  Terminate program\n");
    exit(1);
    }

 /*  Initialize first list node           */
 p = (node_type *)malloc(sizeof(node_type));
 fscanf(indatpt, "%d", &p->number);
 q = p;              /* q points to first list node, too  */

 for  (i = 2; (i <= LISTSIZE && q != NULL); ++i) {         /* add nodes    */
/* Allocate memory for next node, attach to list, store data in it         */
	q->next = (node_type *)malloc(sizeof(node_type));
	q = q->next;                      /* advance pointer to next node  */
	if (q != NULL) {                      /* Be sure malloc succeeded  */
	    fscanf(indatpt, "%d", &q->number);         /*  Get next data   */
	}   /*  end if q != NULL    */
   }        /*  end for loop to build the list */
 fclose(indatpt);
 if (q == NULL)
      p = NULL;   /* not enough memory for list; set list pointer to NULL  */
 else
      q->next = NULL;  /*  be sure to set pointer in last node to NULL     */
 return p;
}

/**********************   function print_list    ****************************/
/*  Preconditions: none                                                    */
/*  Postconditions: The list pointed to by p is printed;                   */
void print_list(node_type *p) {
node_type *temp;
int i = 1;
    printf("The contents of the list:\n");
    for (temp = p; temp != NULL; temp = temp->next)  {
	printf("%d  ",  temp->number);
	++i;
    }
    printf("\n");
return;
}

/*********************        reverse_print          ***********************/
/* Prints a list in reverse order by making repeated recursive calls       */
void reverse_print(node_type *list)  {
if (list != NULL)  {
    reverse_print(list->next);
    printf("%d  ", list->number);
    }
/* terminating case is list == NULL; no action necessary                   */
return;
}
/*********************       function add_node       ***********************/
/* Adds a node to the end of  list.  Successive recursive calls are used   /*
/* to locate the last node in the list, which is identified by the NULL    */
/* pointer.                                                                */
void add_node(node_type **list, int new_val) {
  printf("This is a stub for function add_node.  Insert your code here\n");
 return;
 }
/*********************         main function          **********************/
int main(void)
{
node_type *List;
int N;
printf("\nBEGIN\n");
List = NULL;
List = build_list();
print_list(List);
printf("The contents of the list in reverse order:\n");
reverse_print(List);
printf("\n");
printf("Enter an integer to add to the list.\n");
scanf("%d", &N);
add_node(&List, N);
reverse_print(List);
return(0);
}