Sorting and Displaying a Linked List - c

Question

I am writing a library management program where the user can add books to a database which just means that the program will take the user's input and store it into a text document. Then, when the program starts up it will read through the text document where all the books are stored and build a linked list where each book would be a node. So, I have been able to get to a point where I can read the text file and store the values into nodes. However, when I try testing the bookList function to view the entire book list by title my program crashes. Here is the code:
void loadingMenu(){
FILE *fp = fopen(filename, "r");
int lines = 0;
char line[254];
char *ti = malloc(MAX_STR_LEN);
char *au = malloc(MAX_STR_LEN);
char *ca = malloc(MAX_STR_LEN);
char *id = malloc(MAX_STR_LEN);
char *ti_chopped;
char *au_chopped;
char *ca_chopped;
char *id_chopped;
int id_num;
struct node *tempNode;
while(fgets(line, sizeof(line), fp)){
if(line == 'EOF'){
break;
}
if(lines == 7){
lines = 0;
}
if(lines == 0){
line[strcspn(line, "\n")] = 0; // remove '\n' from string
strcpy(ti, line);
}
else if(lines == 1){
line[strcspn(line, "\n")] = 0;
strcpy(au, line);
}
else if(lines == 3){
line[strcspn(line, "\n")] = 0;
strcpy(ca, line);
}
else if(lines == 6){
line[strcspn(line, "\n")] = 0;
strcpy(id, line);
}
lines++;
if(lines == 6){
// removing the identifiers from each string
ti_chopped = ti + 6;
au_chopped = au + 7;
ca_chopped = ca + 9;
id_chopped = id + 3;
id_num = atoi(id_chopped);
// ------create book node------------
tempNode = malloc(sizeof *tempNode);
// ----------------------------------
tempNode->next = NULL;
tempNode->titleptr = malloc(strlen(ti_chopped) + 1);
strcpy(tempNode->titleptr, ti_chopped);
tempNode->authorptr = malloc(strlen(au_chopped) + 1);
strcpy(tempNode->authorptr, au_chopped);
tempNode->categoryptr = malloc(strlen(ca_chopped) + 1);
strcpy(tempNode->categoryptr, ca_chopped);
tempNode->id = id_num;
//printf("%d", tempNode->id);
head = addNode(head, tempNode);
}
}
fclose(fp);
}
int compareNode(struct node *n1, struct node *n2){
int compareValue = strcmp(n1->titleptr, n2->titleptr);
if(compareValue == 0){
return 0;
}
else if(compareValue < 0){
return -1;
}
else {
return 1;
}
}
struct node *addNode(struct node *list, struct node *node1){
struct node* tmp = list;
if(list == NULL){
return node1;
}
if(compareNode(node1,list) == -1){
node1->next = list;
list = node1;
return list;
}
else
{
struct node* prev = list;
while(tmp != NULL && compareNode(node1, tmp) >= 0){
prev = tmp;
tmp = tmp->next;
}
prev->next = node1;
node1->next = tmp;
return list;
}
}
void bookList(){
system("cls");
struct node *tmp;
tmp = head;
printf("List of all Books: ");
while(tmp != NULL)
{
printf("%s\n", tmp->titleptr);
tmp = tmp->next;
}
printf("\n\nEnd of list.");
}
First off I would like to apologize for the bad code, also I trimmed away some of the fat of the program and just left the functions involved behind.
So, please if you could help me out on this or at least point me in the right direction I would be very grateful. Also, if you have any coding tips or comments go ahead and tell me, I am always hungry to learn!
EDIT: The code now runs and the list will print, however, the strings will not be in alphabetical order. Currently trying to figure that out.

Answer 1

In the first addNode() function, you need to set the previous pointer. That should fix the problem.
if(compareNode(node1,list) == -1)
{
node1->next = list;
list->prev = node1;
list = node1;
return list;
}