The document discusses operations on circular linked lists in C including inserting and deleting nodes from the front and back of the list, displaying the list, concatenating two lists, and searching for a node with a given value and inserting it at the end if not found. It provides functions to insert and delete nodes from the front and back, display the list, concatenate two lists by connecting the last node of the first to the head of the second, and search for a value and insert it at the end if not present. The main function tests these operations with a menu-driven program.

1. P a g e |1
Circular List
/* WAP
1. Insert A Node Into Front Of A Circular Linked List.
2. Delete A Node From The Front End.
3. Display. */
#include<stdio.h>
#include<stdlib.h>
struct node
{
int info;
struct node *next;
};
typedef struct node NODE;
void c_ins_first(NODE**, int);
int c_del_first(NODE**);
void c_display(NODE*);
int main()
{
NODE *first=NULL;
int choice, item;
for(;;)
{
printf("Circular Linked Listn");
printf("1.Insert Frontn");
printf("2.Delete Frontn");
printf("3.Displayn");
printf("4.Exitn");
printf("Enter U R Choicen");
scanf("%d", &choice);
printf("nn");
switch(choice)
{
case 1 : printf("Enter The Item To Insertn");
scanf("%d", &item);
printf("nn");
c_ins_first(&first, item);
break;
case 2 : item=c_del_first(&first);
if(item!='0')
printf("Deleted Element Is %dnn", item);
break;
case 3 : printf("Contents Of Stack Aren");
c_display(first);
break;
default : exit(0);
Ashok R

2. P a g e |2
}
Circular List
}
}
return 1;
void c_ins_first(NODE **first, int item)
{
NODE *newn, *travel;
newn=(NODE*)malloc(sizeof(NODE));
newn->info=item;
if(*first==NULL)
{
newn->next=newn;
*first=newn;
}
else
{
travel=*first;
while(travel->next!=*first)
travel=travel->next;
newn->next=*first;
travel->next=newn;
*first=newn;
}
}
int c_del_first(NODE **first)
{
int item;
NODE *travel, *temp;
if(*first==NULL)
{
printf("List Is Emptynn");
return('0');
}
temp=*first;
travel=*first;
if(temp->next==*first) /* If There Is Only One Node Delete It */
{
item=temp->info;
*first=NULL;
free(temp);
return item;
}
Ashok R

3. P a g e |3
}
Circular List
while(travel->next!=*first) /* List Contain More Than One Nodes */
travel=travel->next;
item=temp->info;
*first=temp->next;
travel->next=temp->next; /* OR travel->next=*first */
free(temp);
return item;
void c_display(NODE *first)
{
NODE *travel;
travel=first;
if(first==NULL)
{
printf("List Is Emptynn");
}
else
{
while(travel->next!=first)
{
printf("%dn", travel->info);
travel=travel->next;
}
printf("%dnn", travel->info);
}
}
Ashok R

4. P a g e |4
Circular List
/* Insert Node Last */
case 4 :
printf("Enter The Item To Insertn");
scanf("%d", &item);
printf("nn");
c_ins_last(&first, item);
break;
void c_ins_last(NODE **first, int item)
{
NODE *newn, *travel;
newn=(NODE*)malloc(sizeof(NODE));
newn->info=item;
if(*first==NULL)
{
newn->next=newn;
*first=newn;
}
else
{
travel=*first;
while(travel->next!=*first)
travel=travel->next;
newn->next=travel->next;
travel->next=newn;
}
}
Ashok R

5. P a g e |5
Circular List
Delete Last
case 5 : item=c_del_last(&first);
if(item!='0')
printf("Deleted Element Is %dnn", item);
break;
int c_del_last(NODE **first)
{
int item;
NODE *travel, *temp;
if(*first==NULL)
{
printf("List Is Emptynn");
return('0');
}
temp=*first;
travel=*first;
if(temp->next==*first) /* If There Is Only One Node Delete It */
{
item=temp->info;
*first=NULL;
free(temp);
return item;
}
while(travel->next!=*first) /* List Contain More Than One Nodes */
{
temp=travel;
travel=travel->next;
}
item=travel->info;
temp->next=travel->next;
free(travel);
return item;
}
Ashok R

6. P a g e |6
Circular List
Ashok R
CIRCULAR LIST.
WRITE A PROGRAM TO SEARCH A NODE WITH A VALUE K , IF IT IS NOT FOUND THEN INSERT VALUE AS
LAST NODE.
void c_ins_k(NODE **first, int k)
{
NODE *newn, *travel, *temp;
int flag=0;
newn=(NODE*)malloc(sizeof(NODE));
newn->info=k;
travel=*first;
if(*first==NULL)
{
/* List Is Empty, So Element k Is Inserted As Last Node */
newn->next=newn;
*first=newn;
}
else if(travel->info==k) /* Item Found At 1st Postion */
flag=1;
else
{
temp=*first; /* Initially Pointing To 1st Item In A List */
travel=temp->next; /* Initially Pointing To 2nd Item In A List */
while(travel!=*first && flag==0)
{
if(travel->info==k)
{
flag=1;
break;
}
travel=travel->next;
}
}
}
if(flag==1)
printf("%d Foundn", k);
else
/* If Item Not Found */
{
travel=*first;
while(travel->next!=*first)
travel=travel->next;
newn->next=travel->next;
travel->next=newn;
printf("k=%d Not Found In The List So It Is Inserted As Last Noden", k);
}

7. P a g e |7
Circular List
Write A C Routine That Concatenate Two Circular List.
/* Concatenate two lists. */
#include<stdio.h>
#include<stdlib.h>
struct node
{
int info;
struct node *next;
};
typedef struct node NODE;
void c_ins_first(NODE**, int);
void display(NODE*);
void concat(NODE**, NODE**);
int main()
{
NODE *first1=NULL;
NODE *first2=NULL;
int choice, item;
for(;;)
{
printf("Stack Menun");
printf("1.In First List To Insert Frontn");
printf("2.In Second List To Insert Frontn");
printf("3.To Display First Listn");
printf("4.To Display Second Listn");
printf("5.To Concate Both List & To Displayn");
printf("6.Exitn");
printf("Enter U R Choicen");
scanf("%d", &choice);
printf("nn");
switch(choice)
{
case 1 :
printf("First Listn");
printf("Enter The Item To Insertn");
scanf("%d", &item);
printf("nn");
c_ins_first(&first1, item);
break;
Ashok R

8. P a g e |8
Circular List
case 2 : printf("Second Listn");
printf("Enter The Item To Insertn");
scanf("%d", &item);
printf("nn");
c_ins_first(&first2, item);
break;
case 3 : printf("Contents Of First Listn");
display(first1);
break;
case 4 : printf("Contents Of Second Listn");
display(first2);
break;
case 5 : printf("Concating List Wait....n");
concat(&first1, &first2);
printf("After Concating Elements In List Isn");
display(first1);
break;
default : exit(0);
}
}
}
return 1;
void c_ins_first(NODE **first, int item)
{
NODE *newn, *travel;
newn=(NODE*)malloc(sizeof(NODE));
newn->info=item;
if(*first==NULL)
{
newn->next=newn;
*first=newn;
}
else
{
travel=*first;
while(travel->next!=*first)
travel=travel->next;
newn->next=*first;
travel->next=newn;
*first=newn;
}
}
Ashok R

9. P a g e |9
Circular List
void display(NODE *first)
{
NODE *travel;
travel=first;
if(first==NULL)
{
printf("List Is Emptynn");
}
else
{
while(travel->next!=first)
{
printf("%dn", travel->info);
travel=travel->next;
}
printf("%dnn", travel->info);
}
}
void concat(NODE **first1, NODE **first2)
{
NODE *temp, *travel;
if(*first1==NULL)
*first1=*first2;
else
{
temp=*first1;
while(temp->next!=*first1)
temp=temp->next; /* Now temp Is Pointing To Last Node Of A First Circular List */
travel=*first2;
while(travel->next!=*first2)
travel=travel->next; /*Now travel Is Pointing To Last Node Of A Second Circular List */
}
}
temp->next=*first2;
travel->next=*first1;
Ashok R