Thread: error in c program for binary addition using doubly linkedlist

when i keep a watch, even though initially head1 is NULL it doesn't execute following lines

if(head1==NULL)
{
head1=move;
}


the code is here, please help me

Code:

   #include<stdio.h>
#include<conio.h>
#include<alloc.h>

typedef struct linkedlist
{
	int d;
	struct linkedlist *next;
	struct linkedlist *prev;
}node;

node * createnode(int data)
{
	node *newnode;
	newnode = (node *)malloc(sizeof(node));
	newnode->d=data;
	newnode->next=newnode->prev=NULL;
	return newnode;
}


void main()
{
	int n1,n2,temp,i,sum,carry;
	node *head1,*head2,*head3,*move,*move1,*move2,*move3;

	clrscr();
	head1=head2=head3=NULL;

	printf("\n\nEnter no of bits of first no: ");
	scanf("%d",&n1);
	printf("\n\nEnter Binary no: ");

	for(i=0;i<n1;i++)
	{
		scanf("%d",&temp);

		move=createnode(temp);

		if(head1==NULL)
		{
			head1=move;
		}

		else
		{
			move->next=head1;
			head1->prev=move;
			head1=move;
		}

	}


	printf("\n\nEnter no of bits of second no: ");
	scanf("%d",&n2);
	printf("\n\nEnter Binary no: ");

	for(i=0;i<n2;i++)
	{
		scanf("%d",&temp);

		move=createnode(temp);

		if(head2==NULL)
		{
			head2=move;
		}

		else
		{
			move->next=head2;
			head2->prev=move;
			head2=move;
		}

	}

	/* *********** create linkedlist for addition ********** */

	move1=head1;
	move2=head2;
	move3=head3;

	while(head1!=NULL || head2 !=NULL)
	{
		if(head3==NULL)
		{
			head3=createnode(0);
		}
		else
		{
		 move=head3;

		 while(move->next!=NULL)
			move=move->next;

		 move->next=createnode(0);
		}

		move1=move1->next;
		move2=move2->next;

	}

	/* *********** binary addition ********** */

	move1=head1;
	move2=head2;
	move3=head3;

	carry=0;

	while(move3!=NULL)
	{

		sum=(move1->d)+(move2->d)+carry;


		if(sum==3)
		{
			move3->d=1;
			carry=1;
		}
		else if(sum==2)
		{
			move3->d=0;
			carry=1;
		}
		else if(sum==1)
		{
			move3->d=1;
			carry=0;
		}
		else
		{
			move3->d=0;
			carry=0;
		}

		move1=move1->next;
		move2=move2->next;
		move3=move3->next;

	}
/* *********** Display binary addition ********** */

	move=head3;
	printf("\n\nAddition is :\n\n");
	while(move!=NULL)
	{
		printf("  %d",move->d);
	}

	getch();
}

I'm sorry sir, but it doesn't !
I'm using Turbo c++ editor version 3.0 , is it a problem due to editor ?
i have faced the same problem with two different machines but the same editor

thanks for reply

I've never had much luck with debuggers. When the compiler optimizes code placement for loops, the breakpoints get odd behavior. I think the above code works perfectly... it's just the stepping debugger is confused.