Thread: Linked lists--do these programs both clear the list?

What is the difference between these programs? I am studying for an exam and I think the 2nd one is easier to follow, its recursive I know that...

Code:

void ResetList(struct point **ptrFirst, struct point **ptrLast) {
   struct point *current = *ptrFirst;
   struct point *next = NULL;

   // free up all the memory in the list
   while (current != NULL) {
      next = current->ptrNext;
      free(current);
      current = next;
   }

   // update the first and last pointers, which still point to the freed memory
   *ptrFirst = NULL;
   *ptrLast = NULL;
}

Code:

// user must clear ptrFirst and ptrLast
void ClearList(struct node * ptrF)
{
	// base case: empty list
	if (ptrF == NULL)
		return;
	else
	{
		ClearList(ptrF->ptrNext);
		free(ptrF);
	}
}

Look at the last 2 lines of your ResetList function. Notice there's nothing like that in ClearList.

ClearList has the same number of lines of code (excluding the curly braces) if you ignore setting ptrFirst and ptrLast to NULL. Maybe a little "clearer", but not much, IMO.

What do you think might happen if you call ClearList with a list having 1,000,000 elements?

Originally Posted by anduril462

What do you think might happen if you call ClearList with a list having 1,000,000 elements?

A rather large spike in Kevlar sales after the boss finds out?