#include <stdio.h>
#include <stdlib.h>
struct int_linked_list
{
int n;
struct int_linked_list *next;
struct int_linked_list *prev;
};
typedef struct int_linked_list item;
void print_linked_list_ltr(item *head);
void print_linked_list_rtl(item *tail);
void free_linked_list(item *head);
item *insert_at_front(item *head, int val);
item *insert_at_end(item *tail, int val);
void insert_in_middle(item *head, int item_number, int val);
int main(void)
{
item *curr, *head, *tail;
int i = 1;
head = curr = (item *)malloc(sizeof(item));
curr->n = i;
curr->prev = NULL;
for (i = 2; i <= 10; i++)
{
curr->next = (item *)malloc(sizeof(item));
curr->next->n = i;
curr->next->prev = curr;
curr = curr->next;
}
curr->next = NULL;
tail = curr;
printf("Print with next (left to right):\n");
print_linked_list_ltr(head);
printf("\n\nPrint with prev (right to left):\n");
print_linked_list_rtl(tail);
head = insert_at_front(head, 0);
tail = insert_at_end(tail, 11);
insert_in_middle(head, 3, 3000);
insert_in_middle(head, 7, 7000);
printf("Print with next (left to right):\n");
print_linked_list_ltr(head);
printf("\n\nPrint with prev (right to left):\n");
print_linked_list_rtl(tail);
free_linked_list(head);
return 0;
}
void print_linked_list_ltr(item *head)
{
item *curr = head;
while (curr) {
printf("%d ", curr->n);
curr = curr->next;
}
}
void print_linked_list_rtl(item *tail)
{
item *curr = tail;
while (curr) {
printf("%d ", curr->n);
curr = curr->prev;
}
}
void free_linked_list(item *head)
{
item *curr = head;
while (curr) {
curr = curr->next;
free(head);
head = curr;
}
}
item *insert_at_front(item *head, int val)
{
item *new_item = (item *)malloc(sizeof(item));
if (new_item == NULL) exit(1);
new_item->n = val;
head->prev = new_item;
new_item->next = head;
new_item->prev = NULL;
return new_item;
}
item *insert_at_end(item *tail, int val)
{
item *new_item = (item *)malloc(sizeof(item));
if (new_item == NULL) exit(1);
new_item->n = val;
new_item->next = NULL;
new_item->prev = tail;
tail->next = new_item;
return new_item;
}
void insert_in_middle(item *head, int item_number, int val)
{
item *curr = head;
int i = 1;
while (i < item_number - 1)
{
curr = curr->next;
i++;
}
item *new_item = (item *)malloc(sizeof(item));
if (new_item == NULL) exit(1);
new_item->n = val;
new_item->next = curr->next;;
curr->next->prev = new_item;
curr->next = new_item;
new_item->prev = curr;
}
/*
run:
Print with next (left to right):
1 2 3 4 5 6 7 8 9 10
Print with prev (right to left):
10 9 8 7 6 5 4 3 2 1 Print with next (left to right):
0 1 3000 2 3 4 7000 5 6 7 8 9 10 11
Print with prev (right to left):
11 10 9 8 7 6 5 7000 4 3 2 3000 1 0
*/
