Circular Doubly linked list in C Programming

Today I will discuss on circular doubly linked list.

Program on circular doubly linked list without any header node.

 #include< stdio.h >

#include< stdlib.h >

struct list

{

int num;

struct list *next;

struct list *prev;

};

struct list *node;

void create(struct list *n)

{

char ch;

node=n;

printf("\nWant to create location(y/n):-");

scanf("%c",&ch);

fflush(stdin);

while(ch!='n')

{

fflush(stdin);

node->next=(struct list *)malloc(sizeof(struct list));

node->next->prev=node;

node=node->next;

printf("\Enter value:-");

scanf("%d",&node->num);

fflush(stdin);

printf("\Any more (y/n)");

scanf("%c",&ch);

}

node->next=n;

n->prev=node;

}

void display(struct list *n)

{

node=n->next;

while(node!=n)

{

printf("%d\n",node->num);

node=node->next;

}

}

void main()

{

struct list *start=NULL;

clrscr();

create(start);

printf("Now display the value of the circular lists:-\n");

display(start);

getch();

}

 Another program on circular doubly linked list with header node

In this program insertion of new created node at any location of the circular doubly linked list can be done.

#include< stdio.h >

#include< stdlib.h >

struct list

{

int num;

struct list *next;

struct list *prev;

};

struct list *node;

void create(struct list *n)

{

char ch;

node=n;

printf("\nWant to create location(y/n):-");

scanf("%c",&ch);

fflush(stdin);

while(ch!='n')

{

fflush(stdin);

node->next=(struct list *)malloc(sizeof(struct list));

node->next->prev=node;

node=node->next;

printf("\Enter value:-");

scanf("%d",&node->num);

fflush(stdin);

printf("\Any more (y/n)");

scanf("%c",&ch);

}

node->next=n;

n->prev=node;

}

void display(struct list *n)

{

node=n->next;

while(node!=n)

{

printf("%d\n",node->num);

node=node->next;

}

}

void insert(struct list *n)

{

struct list *node,*new1;

int c=1,count;

node=n;

new1=(struct list*)malloc(sizeof(struct list));

printf("\nEnter the location where the new location will be inserted:");

scanf("%d",&count);

printf("\Enter value:-");

scanf("%d",&new1->num);

do

{

if(c==count)

break;

node=node->next;

c++;

}while(node!=n);

new1->next=node->next;

node->next->prev=new1;

node->next=new1;

new1->prev=node;

}

void main()

{

struct list *start;

clrscr();

start=(struct list*)malloc(sizeof(struct list));

/* header node without any value */

create(start);

printf("Now display the value of the circular lists:-\n");

display(start);

insert(start);

printf("\nAfter insertion, the list is\n");

display(start);

getch();

}