Circular Doubly Linked List: Insert at End

Circular 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 last, int item);

void display(NODE last);

NODE getnode()

{

                NODE x;

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

                return x;

}

NODE insert_at_end(NODE last, int item)

{

                int val;

                NODE cur, temp;

                temp = getnode();

                temp->data = item;

                if(last == NULL)

                {

                                last = temp;

                }

                else

                {

                                temp->rlink = last->rlink;

                                last->rlink->llink = temp;

                }

                last->rlink = temp;

                temp->llink = last;

                return temp;

}

void display(NODE last)

{

                NODE cur;

                printf("\nContents are:\n");

                if(last == NULL)

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

                else

                {

                                cur = last->rlink;

                                while(cur != last)

                                {

                                                printf("|%d | %d | %d | ==>  ", cur->llink, cur->data, cur->rlink);

                                                cur = cur->rlink;

                                }

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

                 }

}

void main()

{              int ch, item;

                NODE last = 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);

                                                                                last = insert_at_end(last, item);

                                                                                break;

                                                case 2:                  display(last);

                                                                                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: 2

Contents are:

| 4994112 | 11 | 4994112 |

~~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: 1

Enter the value: 13

~~MENU~~

1.Insert at End

2.Display

3.exit

Enter your choice: 2

Contents are:

|4994160 | 11 | 4994136 | ==>  |4994112 | 12 | 4994160 | ==>  | 4994136 | 13 | 4994112 |