C example of building a linked list

Following is an example of how to build a linked list in a C program using callable services.

/*Module/File Name: EDCLLST   */
 /****************************************************************
  **                                                             *
  **FUNCTION       : CEEGTST - obtain storage from user heap     *
  **                           for a linked list.                *
  **               : CEEFRST - free linked list storage          *
  **                                                             *
  **   This example illustrates the construction of a linked     *
  **   list using the Language Environment storage management    *
  **   services.                                                 *
  **                                                             *
  **                                                             *
  **   1.  Storage for each list element is allocated from the   *
  **       user heap.                                            *
  **                                                             *
  **   2.  The list element is initialized and appended to the   *
  **       list.                                                 *
  **                                                             *
  **   3.  After three members are appended, the list traversed  *
  **       and the count saved in each element is displayed.     *
  **                                                             *
  **   4.  The linklist storage is freed.                       *
  **                                                             *
  ****************************************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <leawi.h>
#include <ceeedcct.h>
void main ()
{
  _INT4 HEAPID;
  _INT4 HPSIZE;
  _INT4 LCOUNT;
  _FEEDBACK FC;
  _POINTER ADDRSS;
  struct LIST_ITEM
       { _INT4 COUNT;
         struct LIST_ITEM *NEXT_ITEM;
       } ;
  struct LIST_ITEM *ANCHOR;
  struct LIST_ITEM *CURRENT;
  _INT4 NBYTES = sizeof(struct LIST_ITEM);

  printf ( "\n**********************************\n");
  printf ( "\nCESCSTO C Example is now in motion\n");
  printf ( "\n**********************************\n");
  ANCHOR = NULL;

  for ( LCOUNT = 1; LCOUNT < 4; LCOUNT++)
    {
     /*******************************************************
      * Call CEEGTST to get storage from user heap          *
      *******************************************************/
     CEEGTST ( &HEAPID , &NBYTES , &ADDRSS , &FC );
     if ( (_FBCHECK (FC , CEE000) == 0) && ADDRSS != 0 )
       /*  ************************************************
        *  If storage is gotten successfully, the linked  *
        *  list elements are pointed to by the pointer    *
        *  variable CURRENT. Append element to the end of *
        *  the list. The list origin is pointed to by the *
        *  variable ANCHOR.                               *
        *  ************************************************/
       {
         if (ANCHOR == NULL)
           {
             ANCHOR =(struct LIST_ITEM *) ADDRSS;
           }else{
             CURRENT -> NEXT_ITEM =(struct LIST_ITEM *)ADDRSS;
           }
           CURRENT =(struct LIST_ITEM *) ADDRSS;
           CURRENT -> NEXT_ITEM = NULL;
           CURRENT -> COUNT = LCOUNT;
       }else{
         printf ( "Error in getting user storage\n" );
       }
     }
     /*********************************************************
      *  On completion of the above loop, we have the         *
      *  following layout:                                    *
      *                                                       *
      *  ANCHOR  -->  LIST-ITEM1 --> LIST-ITEM2 --> LIST-ITEM3*
      *                                                       *
      *  Loop thru list items 1 thru 3 and print out the      *
      *  identifying item number saved in the COUNT field.    *
      *                                                       *
      *  Test the LCOUNT variable to verify that three items  *
      *  were indeed in the linked list.                      *
      *********************************************************/
  CURRENT = ANCHOR;
  while (CURRENT)
    {
      printf("This is list item %d\n", CURRENT->COUNT) ;
      ADDRSS = CURRENT;
      LCOUNT = CURRENT -> COUNT;
      CURRENT = CURRENT -> NEXT_ITEM;
      /*******************************************************
       * Call CEEFRST to free this piece of storage          *
       *******************************************************/
      CEEFRST ( &ADDRSS , &FC );
      if ( _FBCHECK (FC , CEE000) == 0 )
        {
        }else{
           printf ( "Error freeing storage from heap\n" );
        }
    }
   if (LCOUNT == 3)
    {
     printf ( "\n********************************\n" );
     printf ( "\nC/370 linked list example ended.\n" );
     printf ( "\n********************************\n" );
     exit(0);
    }else{
     printf ( "Error in constructing linked list\n" );
    }
  exit(-1);
}