LINEAR LINKED LIST

/* Write a program to create a linear linked list interactively and print out the list and the total number of items in the list. */


#include
#include
#define NULL 0

struct linked_list
{
int number;
struct linked_list *next;
};
typedef struct linked_list node; /* node type defined */

main()
{
node *head;
void create(node *p);
int count(node *p);
void print(node *p);
head = (node *)malloc(sizeof(node));
create(head);
printf("\n");
printf(head);
printf("\n");
printf("\nNumber of items = %d \n", count(head));
}
void create(node *list)
{
printf("Input a number\n");
printf("(type -999 at end): ");
scanf("%d", &list -> number); /* create current node */

if(list->number == -999)
{
list->next = NULL;
}

else /*create next node */
{
list->next = (node *)malloc(sizeof(node));
create(list->next); */ Recursion occurs */
}
return;
}
void print(node *list)
{
if(list->next != NULL)
{
printf("%d-->",list ->number); /* print current item */

if(list->next->next == NULL)
printf("%d", list->next->number);

print(list->next); /* move to next item */
}
return;
}

int count(node *list)
{
if(list->next == NULL)
return (0);
else
return(1+ count(list->next));
}

Output

Input a number
(type -999 to end); 60
Input a number
(type -999 to end); 20
Input a number
(type -999 to end); 10
Input a number
(type -999 to end); 40
Input a number
(type -999 to end); 30
Input a number
(type -999 to end); 50
Input a number
(type -999 to end); -999

60 -->20 -->10 -->40 -->30 -->50 --> -999

Number of items = 6


/* Write a function for deleting an item from linked list */


node *delete(node *head)
{
node *find(node *p, int a);
int key; /* item to be deleted */
node *n1; /* pointer to node preceding key node */
node *p; /* temporary pointer */
printf("\n What is the item (number) to be deleted?");
scanf("%d", &key);
if(head->number == key) /* first node to be deleted) */
{
p = head->next; /* pointer to 2nd node in list */
free(head); /* release space of key node */
head = p; /* make head to point to 1st node */
}
else
{
n1 = find(head, key);
if(n1 == NULL)
printf("\n key not found \n");
else /* delete key node */
{
p = n1->next->next; /* pointer to the node
following the keynode */

free(n1->next); /* free key node */
n1->next = p; /* establish link */
}
}
return(head);
}
/* USE FUNCTION find() HERE */
/* Write a function for inserting an item into a linked list */


node *insert(node *head)
{
node *find(node *p, int a);
node *new; /* pointer to new node */
node *n1; /* pointer to node preceding key node */
int key;
int x; /* new item (number) to be inserted */

printf("Value of new item?");
scanf("%d", &x);
printf("Value of key item ? (type -999 if last) ");
scanf("%d", &key);

if(head->number == key) /* new node is first */
{
new = (node *)malloc(size of(node));
new->number = x;
new->next = head;
head = new;
}
else /* find key node and insert new node */
{ /* before the key node */
n1 = find(head, key); /* find key node */

if(n1 == NULL)
printf("\n key is not found \n");
else /* insert new node */
{
new = (node *)malloc(sizeof(node));
new->number = x;
new->next = n1->next;
n1->next = new;
}
}
return(head);
}
node *find(node *lists, int key)
{
if(list->next->number == key) /* key found */
return(list);
else

if(list->next->next == NULL) /* end */
return(NULL);
else
find(list->next, key);
}