Doubly Linked List: Insert at End

Doubly Linked List: Insert at End

#include<stdio.h>

#include<stdlib.h>

struct node

{

        int data;

        struct node *llink;

        struct node *rlink;

};

typedef struct node* NODE;

NODE getnode();

NODE insert_at_end(NODE first, int item);

void display(NODE first);

NODE getnode()

{

        NODE x;

        x =(NODE) malloc(sizeof(struct node));

        x->llink=NULL;

        x->rlink=NULL;

        return x;

}

void display(NODE first)

{

            NODE cur;

            cur = first;

            printf("\nContents are:");

            if(cur == NULL)

                        printf("\nList is empty. Nothing to display.");

            else

            {

                        while(cur!=NULL)

                        {

                                    printf("%d  ", cur->data);

                                    cur = cur->rlink;

                        }

            }

}

NODE insert_at_end(NODE first, int item)

{

            int val;

            NODE cur, temp;

            temp = getnode();

            temp->data = item;

            if(first == NULL)                               /*Case 1: List is empty*/

            {

                        return temp;

            }

/*Case 2: List not empty.  Update the link field of last node to point to temp node.*/

            cur = first;

             while(cur->rlink != NULL)

            {

                        cur = cur->rlink;

            }         

            cur->rlink = temp;

            temp->llink = cur;

            return first;

}

void main()

{

            int ch, item;

            NODE first = NULL;

            while(1)

            {

                        printf("\n\n~~MENU~~");

                        printf("\n1.Insert at end");

                        printf("\n2.Display");

                        printf("\n3.exit");

                        printf("\nEnter your choice: ");

                        scanf("%d",&ch);

                        switch(ch)

                        {

                                    case 1:                         printf("\nEnter the value: ");

                                                            scanf("%d", &item);

                                                            first = insert_at_end(first, item);

                                                            break;

                                    case 2:             display(first);

                                                            break;

                                    case 3:     exit(0);

                        }

            }

}

Output:

~~MENU~~

1.Insert at end

2.Display

3.exit

Enter your choice: 1

Enter the value: 11

~~MENU~~

1.Insert at end

2.Display

3.exit

Enter your choice: 1

Enter the value: 12

~~MENU~~

1.Insert at end

2.Display

3.exit

Enter your choice: 2

Contents are: 11        12