/*	lin ked_list_4.c
 *
 *  Write a C Program to create a linked list and display the linked_list elements on the screen. 
 *	A linked-list is an ordered set of data elements, each containing a link 
 *	to its next node. 
 */
#include <stdio.h>	// needed to print anything on the screen
#include <malloc.h>	// .h file to allocate additional memory when a new node is to be created 
// #include <stdlib.h>

void main()					// main function returns nothing
{
    struct node				// the structure that creates, adds and sisplays a node
    {
        int num;			// any variable
        struct node *ptr;	// pointer to the next node
    }; 
    typedef struct node NODE;	// NODE is declared to be of type struct node

    NODE *head, *first, *temp = 0;	// *head, *first, *temp are all variables of type struct node

    int count = 0;			// just a counter
    int choice = 1;			// choice variable
    first = 0;				// points to root

    while (choice)			// while choice is 1, keep creating new node
    {
        head  = (NODE *)malloc(sizeof(NODE));	// head points to the beginning of the allocated new memory 
        printf("Enter the data item\n");		// a data item is entered and assigned to num in struct node
        scanf("%d", &head->num);				// value entered from keyboard

        if (first != 0)			// if the initial node exists
        {
            temp->ptr = head;	// head points to the newly allocated memory block and assigned to temp->ptr
            temp = head;		// head is stored in a temporary location called temp
        }
        else					// if first == 0, no node exists, hence create a new node
        {
            first = temp = head;	// first, temp and head points to nowhere (or zero memory)
        }

        fflush(stdin);			// whatever entered from keyboard, display it on the screen

        printf("Do you want to continue(Type 0 or 1)?\n");	// continou to enter new node, hence data
        scanf("%d", &choice);								// assign entered value to choice
    }

    temp->ptr = 0;				// temp->ptr initially points to nowhere

    temp = first;				// reset temp to the beginning, identified by first */

    printf("\n status of the linked list is\n");

    while (temp != 0)				// while temp points somewhere such as beginning of the allocated memory block
    {
        printf("%d=>", temp->num);	// print the value entered from the keyboard
        count++;					// increment counter
        temp = temp -> ptr;			// store temp->prt in a tremporary location
    }

    printf("NULL\n");				// print null
    printf("No. of nodes in the list = %d\n", count);
}