building a stack

[nbelitz]

I need help modifying this code that builds a queue to one that builds a stack

  /* =========================  MakeList ()  ============================ */
/*  Builds a linked list of names based on data from a file.  This      */
/*  functions calls MakeNode () and LoadNode () program functions.      */
/*  It returns a pointer to the start of the list it built.             */
/* ==================================================================== */
struct record * MakeList ( void )
{
  FILE * fp;                    /* output file pointer         */ 
  struct record * start = NULL, /* @ of first node in list     */
                * current,      /* @ of where we are at any pt */
                * new;          /* some pointers to use later  */
  char buffer [ 81 ];           /* space for string from file  */

/* check output file success */
  if ( ( fp = fopen ( FILENAME, "r" ) ) == NULL ) {
    printf ( "MAKELIST: Unable to open input file %s!\n", FILENAME );
    exit ( 1 );
    }

  fgets ( buffer, 81, fp );              /* do a 'priming read'      */
  while ( ! feof ( fp ) ) {     /* read & process all file contents  */
    new = MakeNode ();
    if ( start == NULL )
      start = current = new;             /* start a new list         */
    else {
      current->next = new;               /* move pointer to new node */
      current = current->next;
      }
    LoadNode ( current, buffer );
    fgets ( buffer, 81, fp );            /* get rady for next test   */
    }
  fclose ( fp );
  return start;
}  /* --------------------  end MakeList ()  -------------------------- */

/* =========================  LoadNode ()  ============================ */
/*  Loads a list node with data from a string passed in.  Calls no      */
/*  program other functions.                                            */
/*     Parms:  locn := ptr to list node to be filled                    */
/*             str  := holds source data to be separated and loaded     */
/* ==================================================================== */
void LoadNode ( struct record * locn, char str [] )
{
  sscanf ( str, "%s %s %d %f", locn->first, locn->last, &locn->age, 
    &locn->average );
  return;
}  /* --------------------  end LoadNode ()  -------------------------- */

/* =========================  MakeNode ()  ============================ */
/*  Creates a new node of record type and returns pointer to it.        */
/*  Calls no other program functions.                                   */
/* ==================================================================== */
struct record * MakeNode ( void )
{
  struct record * newptr;     /* a local pointer */

/* dynamicaly allocate some storage and initialize */
  newptr = ( struct record * ) calloc ( 1, sizeof ( struct record ) );
  newptr->next = NULL;
  return newptr;    /* send address of new node back */
}  /* --------------------  end MakeNode ()  -------------------------- */

[Salem]

But it already is a stack.
All you need is a function which takes nodes off the tail, rather than the head and you're done.

Your file reading loop would be much simpler written as
while ( fgets ( buffer, 81, fp ) != NULL )
One less fgets() call, and one less feof() call.

[nbelitz]

with a stack don't you have to update to start pointer on each loop iteration?

[Salem]

Or change this code so it pushes to the front of the queue rather than appends to the end.

Doesn't make a bean of difference to me, your code, your choice.
Either will work if done right.