Thread: Doubly Linked Lists ???????

Hi everyone, could u guys help me figure out, what a possible error for this Thread Stop could be? I am writing a function for Insertion Sort in Doubly Linked Lists. I am posting my code. I know that it is not the clearest code ever , but at least it makes sense to me. I use *trailing and *current to traverse through the list. After a place for the new node (*student) is found , it is inserted and then *trailing and *current are set to the beginning of the list again. Dbase-students is the master database pointer. I think the function UnarchiveStudent works properly. Most likely the problem is created from reassigning the pointers. The Thread Stops at the strcmp(.....) line right after while (1).......I've been stucked on this function for too long and I just can't see it......Appreciate any kind of help. THANKS


int LoadDatabase(Database *dBase)
{
FILE *f;
StudentRecord *student, *trailing=NULL, *current=NULL;
int i=0;

f = fopen("Database.txt","r"); // check if the file has open properly
if(f == NULL) {
printf("Cannot open that file");
return -1;
}

/* unarchive all the students and put them in the list */
while ( (student = UnarchiveStudent(f) )!= NULL)
{
if(current == NULL) //if the list is empty
{
dBase->students = student;
student->prev = student->next = NULL;
trailing = current = student;
}
else if ( (current != NULL) && (current->next == NULL) ) /*if there is only one node in the list*/
{
if (strcmp(student->sLastName, current->sLastName) > 0) /*insert after that single node*/
{
student->next = NULL;
student->prev = current;
current->next = student;
}
else /*insert before that single node, right after the head*/
{
student->next = current;
student->prev = NULL;
dBase->students = student;
current->prev = student;
trailing = current = student;
}
}
else /*if the list already consists of many nodes*/
{
while(1)
{
if (strcmp(student->sLastName, current->sLastName) > 0) //if the name is still >, keep going along the list
{
trailing = current;
current = current->next;
}
//the node has to be inserted now !!!
else if (trailing == current ) //if we have to insert in the beginning, right after the head
{
student->next = current;
student->prev = NULL;
current->prev = student;
dBase->students = student;
break;
}
else if ( (current->next) != NULL)//if the end of the list hasn't been reached yet,insert before the current position and after trailing */
{
student->next = current;
student->prev = trailing;
trailing->next = student;
current->prev = student;
break;
}
else /*if the insertion has to be performed at the end of the list*/
{
student->next = NULL;
student->prev = current;
current->next = student;
break;
}
}
//move back trailing and current to the beginning of the list in the right order
current = trailing = dBase->students;
trailing->prev = current->prev = NULL;
}
i++;
}

(dBase->studentCount) = i;
fclose(f);

return 0;
}
if (strcmp(student->sLastName, current->sLastName) > 0)

on the line where I have:
trailing = current = student;
does it mean that prev and next of trailing and current will be automatically set to prev and next of student?

I am pasting the code more clearly...sorry

Code:

int LoadDatabase(Database *dBase)
{
	FILE *f;
	StudentRecord *student, *trailing=NULL, *current=NULL;
	int i=0;

   f = fopen("Database.txt","r");     // check if the file has open properly
  if(f == NULL) {
	   printf("Cannot open that file");
   	return -1;
 	}

   /* unarchive all the students and put them in the list */
	while	( (student = UnarchiveStudent(f) )!= NULL)
   {
		if(current == NULL)          //if the list is empty
      {
         dBase->students = student;
         student->prev = student->next = NULL;
         trailing = current = student;
      }
      else  if ( (current != NULL) && ( (current->next) == NULL) ) /*if there is only one node in the list*/
      {
      	if (strcmp(student->sLastName, current->sLastName) > 0) /*insert after that single node*/
         	{
            	student->next = NULL;
               student->prev = current;
               current->next = student;
            }
         else  /*insert before that single node, right after the head*/
         {
         	student->next = current;
            student->prev = NULL;
            dBase->students = student;
            current->prev = student;
            trailing = current = student;
         }
      }
      else                 /*if the list already consists of many nodes*/
      {
      	while(1)
         {
            if (strcmp(student->sLastName, current->sLastName) > 0) //if the name is still >, keep going along the list
            {
            	trailing = current;
               current = current->next;
            }
            //the node has to be inserted now !!!
            else if (trailing == current ) //if we have to insert in the beginning, right after the head
            {
            	student->next = current;
               student->prev = NULL;
               current->prev = student;
               dBase->students = student;
               break;
            }
            else  if ( (current->next) != NULL)//if the end of the list hasn't been reached yet,insert before the current position and after trailing */
            {
            	student->next = current;
               student->prev = trailing;
               trailing->next = student;
               current->prev = student;
               break;
            }
            else          /*if the insertion has to be performed at the end of the list*/
            {
            	student->next = NULL;
         		student->prev = current;
         		current->next = student;
					break;
            }
         }
         //move back trailing and current to the beginning of the list in the right order
         current = trailing = dBase->students;
			trailing->prev = current->prev = NULL;
      }
      i++;
   }

 	(dBase->studentCount) = i;
   fclose(f);

 	return 0;
}

ok 10x that looks a lot neater
i'll try