program to create two way linked list

program to create two way linked list.

#include<stdio.h>

#include<conio.h>

#include<alloc.h>

#define NULL 0

void main()

{

struct dnode

{

struct dnode *prev;

int data;

struct dnode *next;

}*start,*temp,*k,*p,*pre;

int i,c;

char ch;

clrscr();

start=NULL;

for(i=0;i<=1;i++)

{

if(start==NULL)

{

temp=(struct dnode*)malloc(sizeof(struct dnode));

printf("\nEnter the value for node: -");

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

start= temp;

temp->prev=NULL;

temp->next=NULL;

}

else

{

while(1)

{

printf("\nDo you want to create one more node(Y/N):- ");

fflush(stdin);

scanf("%c",&ch);

if(ch=='y' || ch=='Y')

{

temp->next=(struct dnode*)malloc(sizeof(struct dnode));

printf("\nEnter the value of  node: -");

k=temp->next;

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

k->prev=temp;

k->next=NULL;

temp=k;

}

else

{

temp->next=NULL;

break;

}

}

}

}

//For forward Displaying the linked list.

printf("\n\n\nBy forward Displaying: -");

printf("\nNodes of linked list are-\n");

temp=start;

while(temp!=NULL)

{

printf("%4d",temp->data);

temp=temp->next;

}

//For backward Displaying the linked list.

printf("\n\n\nBy backward Displaying:");

printf("\nNodes of linked list are-\n");

temp=k;

while(temp!=NULL)

{

printf("%4d",temp->data);

temp=temp->prev;

}

getch();

}

output:

Enter the value for node: -14

Do you want to create one more node(Y/N):- y

Enter the value of  node: -63

Do you want to create one more node(Y/N):- y

Enter the value of  node: -87

Do you want to create one more node(Y/N):- y

Enter the value of  node: -69

Do you want to create one more node(Y/N):- y

Enter the value of  node: -100

Do you want to create one more node(Y/N):- n

By forward Displaying: -

Nodes of linked list are-

  14  63  87  69 100

By backward Displaying:

Nodes of linked list are-

 100  69  87  63 14