Insertion At Location in doubly linked list

Algorithm

InsertAtlocDll(info,prev,next,start,end,loc,size)

1.set nloc = loc-1 , n=1

2.create a new node and address in assigned to ptr.

3.check[overflow] if(ptr=NULL)

      write:overflow and exit 

4.set Info[ptr]=item;

5.if(start=NULL) 

      set prev[ptr] = next[ptr] = NULL 

      set start = end = ptr

  else if(nloc<=size) 

      repeat steps a and b while(n != nloc)

    	

		a.	loc = next[loc]

		b.	n = n+1 

		[end while]

		next[ptr] = next[loc] 

		prev[ptr] = loc 

		prev[next[loc]] = ptr 

		next[loc] = ptr 

   else

      set prev[ptr] = end

      next[end] = ptr

      set ptr[next] = NULL

      set end = ptr

      [end if]

6.Exit.          

Fuction For Insert at Location

void insertAtloc(node **start,node **end,int item , int i,int size )

{

	node *ptr,*loc;

	int n=1 ;

	i=i-1;

	ptr=(node*)malloc(sizeof(node));

	ptr->info=item;

	loc = *start ;

	if(*start==NULL)

	{

		ptr->prev = ptr->next = NULL ;

	*start = *end = ptr ;

	}

	else if(i<=size)

	{   while(n != i)

		{

			loc=loc->next;

			n++;

		}

		ptr->next = loc->next ;

		ptr->prev = loc ;

		(loc->next)->prev = ptr ;

		loc->next = ptr ;







	}

	else

	{

		ptr->prev = *end;

		(*end)->next = ptr ;

		ptr->next= NULL;

		(*end)=ptr;

	}

}

C programe for insertion at location in dubly linked list

#include<stdio.h>

#include<malloc.h>

#include<conio.h>

typedef struct Node

{

	struct Node *prev;

	int info ;

	struct Node *next;

}node;



void createdub(node**,node**,int);

void insertAtloc(node **,node**,int,int,int);

void display(node *);



void main()

{

	int ch, item, pos,loc,i;

	node *start ,*end ;

	start = end = NULL;

	clrscr();

	printf("Enter number of node: ");

	scanf("%d",&i);

	createdub(&start,&end,i);

	printf("\nThe list is : ");

	display(start);

	printf("\nEnter the loc : ");

	scanf("%d",&loc);

	printf("\n\nEnter the item to be inserted at loc : ");

	scanf("%d",&item);

	insertAtloc(&start,&end,item,loc,i);

	printf("\nNow the list is : ");

	display(start);

	getch();

}

void createdub(node **start,node **end,int i)

{       int item ,k=1;

	while(i)

	{ node *ptr;

	printf("\nEnter the info for node %d : ",k);

	scanf("%d",&item);

	ptr=(node*)malloc(sizeof(node));

	ptr->info=item;

	if(*start==NULL)

	{

		ptr->prev = ptr->next = NULL ;

		*start = *end = ptr ;

	}

	else

	{

		ptr->prev = *end;

	(*end)->next = ptr ;

		ptr->next= NULL;

		(*end)=ptr;

	}

	i--;

	k++;

	}

}

void insertAtloc(node **start,node **end,int item , int i,int k )

{

	node *ptr,*loc;

	int n=1 ;

	i=i-1;

	ptr=(node*)malloc(sizeof(node));

	ptr->info=item;

	loc = *start ;

	if(*start==NULL)

	{

		ptr->prev = ptr->next = NULL ;

	*start = *end = ptr ;

	}

	else if(i<=k)

	{   while(n != i)

		{

			loc=loc->next;

			n++;

		}

		ptr->next = loc->next ;

		ptr->prev = loc ;

		(loc->next)->prev = ptr ;

		loc->next = ptr ;







	}

	else

	{

		ptr->prev = *end;

		(*end)->next = ptr ;

		ptr->next= NULL;

		(*end)=ptr;

	}

}



void display(node *start)

{

     while(start !=NULL)

     { printf("\t %d",start->info);

       start = start->next;

     }

}

Output