1. Double Linked List Operations Dr. David Tsai 2010/4/12

2. void createDList (int len, int*array) { int i; DList newnode, before; first = (DList) malloc (sizeof (DNode) ); first->data = array[0]; first->previous = first->next = NULL; before = first /*now = first; */ for (i = 1; i < len; i++) { newnode = (DList) malloc (sizeof(Dnode) ); newnode->data = array[i]; newnode->next = NULL; newnode->previous = before; before->next = newnode; before = newnode; } C /

3. 60 first NULL before 50 newnode NULL 40 NULL

4. void printDList () { DList now = first; while (now! = NULL) { back = now; printf ( %d, now->data); now = now->next; } printf ( \n ); now = back->previous; while (now! = NULL) { back = now; printf ( %d, now->data); now = now->previous; } printf ( \n ); }

5. now 60 first NULL 50 NULL 40 back

6. void deleteDNode (DList ptr) { if (ptr->previous == NULL) { first = first->next; first->previous = NULL; } else { if (ptr->next == NULL) { ptr->previous->next = NULL; } else{ ptr->previous->next = ptr->next; ptr->next->previous = ptr->previous; } free (ptr); }

7. ptr 60 first NULL 50 NULL 302040 NULL To Delete First Node

8. ptr 60 first NULL 50 NULL 302040 To Delete Last Node NULL

9. ptr 60 first NULL 50 NULL 302040 To Delete a Middle Node

10. void insertDNode (DList ptr, int d) { DList newnode = (DList) malloc (sizeof (DNode) ) ; newnode->data = d; newnode->next = newnode->previous = NULL; if (first == NULL) { first = newnode; } if (ptr == NULL) { newnode->previous = NULL; newnode->next = first; first->previous = newnode; first = newnode; } else { if (ptr->next == NULL) { ptr->next = newnode; newnode->previous = ptr; newnode->next = NULL; } else { ptr->next->previous = newnode; newnode->next = ptr->next; newnode->previous = ptr; ptr->next = newnode; } } }

11. 50 first = 40 newnode == = = 60 ptr = = To Create a Double Linked List To Insert a New Node at Front of the First Node To Insert a New Node at End of the Last Node

12. 50 first 40 newnode = = = 60 ptr = 55 To Insert a New Node into the Middle of the List