Friday, 5 July 2013

THIS PROGRAM DELETES THE LAST NODE FROM DOUBLY LINKED LIST




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

struct dlist
{
    int info;
    struct dlist *link;
    struct dlist *prev;
};

int i ;
struct dlist start, *prev;

void del_last (struct dlist *);
void create_dlist (struct dlist *);
void display (struct dlist *);



 /* Function to  create doubly linked list */
void create_dlist(struct dlist *ptr)
{
    int n;
    start.link = NULL;  /* Empty list */
    start.prev = NULL;
    ptr = &start;      /* Ptr points to the start pointer */
    printf("\n How many nodes you want to create: ");
    scanf("%d",&n);
    printf("\n\n ==============================================================================\n");
    printf("\n Note That:\n -----------\n Enter numeric data in nodes\n");
    printf("\n ==============================================================================\n");
    while( i!=n)
    {
        ptr->link = (struct dlist *) malloc(sizeof(struct dlist));
        ptr->link->prev = ptr;
        ptr = ptr->link;
        printf("\n Enter the values of the node : %d: ", (i+1));
        scanf("%d", &ptr->info);
        ptr->link = NULL;
        fflush(stdin);
        i++;
    }
    printf("\n\n --------------------");
    printf("\n Total nodes = %d",i);
    printf("\n --------------------\n\n");
}

   /* Function to delete last node */

void del_last(struct dlist *ptr)
{

    ptr = start.link;
    prev = &start;

    if (ptr == NULL)
    {
        printf("\n\n\n ----------");
        printf("\n Underflow");
        printf("\n ----------");
    }

    else

        while(ptr->link)
        {
            ptr = ptr->link;
            prev = prev->link;
        }

        prev->link = ptr->link;
        free(ptr);


}

/* Function to display the list */

void display(struct dlist *ptr)
{
    ptr = start.link;

        while (ptr)
        {

            printf("\n\n\t\t%d", ptr->info);
            ptr = ptr->link;
        }
}

/* Main Function */

void main()
{
    struct dlist *ptr = (struct dlist *) malloc(sizeof(struct dlist));
    clrscr();
    create_dlist (ptr);
    printf("\n Doubly linked list is:\n");
    printf("\n ----------------------");
    display(ptr);
    del_last(ptr);
    printf("\n\n -----------------------------------------------");
    printf("\n Doubly linked list after deletion of last node:");
    printf("\n -----------------------------------------------");
    display(ptr);
    getch();
}

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