/* This program segment creates a doubly linked list then prints in forward and backword */

#include <stdio.h>
#include <malloc.h>

void main(void)
{
	int i;

	struct ListEntry {
		int number;
		struct ListEntry *next;
		struct ListEntry *previous;
	} start, *node;

	start.next = NULL;  /* Empty list */
	start.previous = NULL;
	node = &start;      /* Point to the start of the list */

	for (i = 1; i <= 10; i++)
	{
		node->next = (struct ListEntry *) malloc(sizeof(struct ListEntry));
		node->next->previous = node;
		node = node->next;
		node->number = 50+i;
		node->next = NULL;
	}

	/* Display the list */

	node = start.next;

	do {
		printf("%d ", node->number);
		node = node->next;
	} while (node->next);  /* Show 60 only one time */


	do {
		printf("%d ", node->number);
		node = node->previous;
	} while (node->previous);
}

/*  INSERT A NODE INTO A SIMPLE LINKED LIST AT THE END OF THE LIST */
# include <stdio.h>
# include <malloc.h>
# include<conio.h>

struct link
{
	char info[20];
	struct link *next;
};

int i,number;
struct link *start, *previous, *new;

void create_list(struct link *node)
{
	char ch;
	start->next = NULL;  /* Empty list */

	start->next=node;      /* Point to the start of the list */
	i = 0;
	while(ch != 'n')
	{
		printf("\n Input the node: %d: ", (i+1));
		gets(node->info);
		fflush(stdin);

		node->next = NULL;

		printf("\n Input choice n for break: ");
		ch = getchar();
		fflush(stdin);
			i++;
		if(ch!='n')
		{
		node->next = (struct link* ) malloc(sizeof(struct link));
		node = node->next;
		}
	}
}

void insertion(struct link *node)
{
	node = start->next;
	previous = start;

	while(node)
	{
		node = node->next;
		previous= previous->next;
	}
	if(node == NULL)
	{
		new= (struct link* ) malloc(sizeof(struct link));
		new->next=NULL;
		previous->next=new;

		printf("\n Input the last node value: ");
		gets(new->info);
		fflush(stdin);
	}
}

void display(struct link *node)
{
	node = start->next;

	while (node)
	{
		printf("\n 0x%x", node);
		printf(" %s", node->info);
		node = node->next;
	}
}

void main()
{
	struct link *node = (struct link *) malloc(sizeof(struct link));
clrscr();
	create_list(node);
printf("\n Created list is as follows:\n");
	display(node);
	insertion(node);
printf("\n After Inserting a node list is as follows:\n");
	display(node);
	getch();
}