bst and doubly linked list
Happy New Year for all!!!
I have a problem and I need your help. It is about image file manipulation in C.
I have a BST (binary search tree) and a doubly linked list:
Code:
this is a part of my given definitions
// Double-linked list node definition.
// Multiple loaded images are stored in such lists
typedef struct image_entry
{
IMAGE *image;
char name[255];
int changed;
struct image_entry *next;
struct image_entry *previous;
} IMAGE_ENTRY;
// A Binary Search Tree (BST) node, in order to index the images
typedef struct node
{
IMAGE_ENTRY *image_entry;
struct node *parent;
struct node *left;
struct node *right;
} NODE;
extern NODE *ROOT; // Initially the BST is empty
extern IMAGE_ENTRY *LIST; // Initially no bmp file is loaded
I have to write a function to close the image file, that is
a) delete the image from the list
b) delete the image from memory
c) delete the node from tree
I have implement the following:
Code:
int close_file(char name[])
{
IMAGE_ENTRY *image_entry;
//Find the node in the linked-list using the BST index.
NODE *n=(NODE*) bst_find(ROOT,name); //already constructed
if (n==NULL) {
printf("There is no file named %s.\n",name);
return EXIT_FAILURE;
}
else
{ image_entry=n->image_entry; }
if (LIST==NULL) {
printf("list is empty\n");
return EXIT_FAILURE;
}
//delete from list
if(image_entry->previous==NULL)
LIST->next=image_entry->next;
else
image_entry->previous->next = image_entry->next;
if(image_entry->next==NULL)
LIST->previous=image_entry->previous;
else
image_entry->next->previous = image_entry->previous;
n->image_entry=image_entry;
//delete from bst
bst_delete(ROOT,n); //already constructed
//delete from memory
free(image_entry->image);
free(image_entry);
return EXIT_SUCCESS;
}
BUT it only works fine for a node that it's in the middle of the list...
The problem appears when i try to delete from the begining or the end of the list....
What am I doing wrong???
Thanks in anvance!!! |
