Circular linked list

 AIM:

To implement circular linked list using C.

ALGORITHM:

1. Start the program.

2. Create the list by getting no. of nodes and nodes as an input.

3. Display the list.

4. Enter the choice

a) If choice is 1, Insertion takes place at the first position.

b) If choice is 2, Insertion takes place after the given node.

c) If choice is 3, Insert an item in to the list at last.

d) If choice is 4, Delete an item at beginning.

e) If choice is 5, Delete the given item from the list.

f) If choice is 6, Delete at end.

g) If choice is 7, then Exit.

5. Stop the program.

PROGRAM:

// Implementation of Circular Linked List

#include <stdio.h>

#include <stdlib.h>

struct node

{

 int data;

 struct node *next;

 };

struct node *head=NULL,*p,*q,*t,*last=NULL;

void display(void);

void insert_begin(void);

void insert_after(void);

void insert_end(void);

void del_begin(void);

void del(void);

void del_end(void);

int x;

int main()

{

 int ch, n, i;

 clrscr();

 printf ("Enter the number of nodes:\t");

 scanf("%d",&n);

 t=head; 

for(i=0;i<n;i++)

 {

 p=malloc(sizeof(struct node));

 printf("Enter the data of node %d \t",i+1);

 scanf("%d",&p->data);

 p->next=NULL;

 if(head==NULL)

 {

head=p;

head->next=head;

 }

 else

 {

t->next=p;

p->next=head;

 }

 t=p;

 }

last=t;

display();

printf(“\nMenu”);

printf("\n 1.Insert at beginning \n 2.Insert after the given node \n 3.Insert at end \n");

printf(" 4.Delete at beginning \n 5.Delete the given node \n 6.Delete at last \n 7.Exit \n");

do

 {

 printf("\nEnter the option \t");

 scanf("%d",&ch);

 t=head;

switch(ch)

 {

case 1:

insert_begin();

display();

break;

case 2:

insert_after();

display();

break;

case 3:

insert_end();

display();

break;

case 4:

del_begin();

display();

break; 

case 5:

del();

display();

break;

case 6:

del_end();

display();

break;

case 7:

printf("Thank You");

getch();

 }

 }while (ch!=7);

return 0;

}

void insert_begin()

{

 p=malloc(sizeof(struct node));

printf("Enter the data to be inserted\t");

scanf("%d",&p->data);

p->next=head;

last->next=p;

head=p;

}

void insert_after()

{

 printf("Enter the previous node value where the new node to be inserted \t");

 scanf("%d",&x);

 p=malloc(sizeof(struct node));

 printf("Enter the data to be inserted\t");

 scanf("%d",&p->data);

 t=head;

 while(x!=t->data)

 t=t->next;

 if(t->next!=head)

 {

 q=t->next;

 p->next=q;

 t->next=p;

 }

else

 {

 t->next=p;

 last=p; 

p->next=head;

 }

 }

void insert_end()

{

 p=malloc(sizeof(struct node));

 printf("Enter the data to be inserted\t");

 scanf("%d",&p->data);

 p->next=head;

 t=head;

 while(t->next!=head)

 t=t->next;

 t->next=p;

 last=p;

 }

void del_begin()

{

 t=head;

 head=head->next;

 t->next=NULL;

 free(t);

 last->next=head;

 }

void del()

{

 printf("Enter the node value to be deleted \t");

 scanf("%d",&x);

 t=head;

 while(x!=t->data)

 {

 p=t;

 t=t->next;

 }

 q=t->next;

 if(t==head)

{

 p->next=q; 

 } 

free(t); 

} 

void del_end() 

{ 

 t=head; 

 while(t->next!=head) 

 { 

 p=t; 

 t=t->next; 

 } 

if(t==head) 

head=NULL; 

else 

 { 

 p->next=head; 

 last=p; 

 free(t); 

 } 

 } 

void display () 

{ 

 printf("The circular linked list is \n"); 

 t=head; 

 printf("-->"); 

 while(t!=last) 

 { 

 printf("%d-->",t->data); 

 t=t->next; 

 } 

printf("%d-->",t->data); 

 } head=head->next;

 last->next=head;

 }

else if (t->next==head)

{

 p->next=head;

 last=p;

}

else 

SAMPLEOUTPUT:

Enter the number of nodes: 5

Enter the data of node1 10

Enter the data of node2 20

Enter the data of node3 30

Enter the data of node4 40

Enter the data of node5 50

The circular linked list is

-->10-->20-->30-->40-->50-->

Menu

1.Insert at beginning

2.Insert after the given node

3.Insert at end

4.Delete at beginning

5.Delete the given node

6.Delete at last

7.Exit

Enter the option 1

Enter the data to be inserted 1

The circular linked list is

-->1-->10-->20-->30-->40-->50-->

Enter the option 2

Enter the previous node value where the new node to be inserted 40

Enter the data to be inserted 100

The circular linked list is

-->1-->10-->20-->30-->40-->100-->50-->

Enter the option 3

Enter the data to be inserted 200

The circular linked list is

-->1-->10-->20-->30-->40-->100-->50-->200-->

Enter the option 4

The circular linked list is

-->10-->20-->30-->40-->100-->50-->200-->

Enter the option 5

Enter the node value to be deleted 30

The circular linked list is

-->10-->20-->40-->100-->50-->200-->

Enter the option 6

The circular linked list is

-->10-->20-->40-->100-->50-->

Enter the option 7

 Thank You

RESULT:

Thus theprogramfor circularlinkedlistimplementationwas executedandverified.