Deletion in Circular doubly linked list at beginning

There can be two scenario of deleting the first node in a circular doubly linked list.

The node which is to be deleted can be the only node present in the linked list. In this case, the condition head → next == head will become true, therefore the list needs to be completely deleted.

It can be simply done by assigning head pointer of the list to null and free the head pointer.

in the second scenario, the list contains more than one element in the list, therefore the condition head → next == head will become false. Now, reach the last node of the list and make a few pointer adjustments there. Run a while loop for this purpose

Now, temp will point to the last node of the list. The first node of the list i.e. pointed by head pointer, will need to be deleted. Therefore the last node must contain the address of the node that is pointed by the next pointer of the existing head node. Use the following statement for this purpose.

The new head node i.e. next of existing head node must also point to the last node of the list through its previous pointer. Use the following statement for this purpose.

Now, free the head pointer and the make its next pointer, the new head node of the list.

in this way, a node is deleted at the beginning from a circular doubly linked list.

Algorithm

• Step 1: IF HEAD = NULL
• Write UNDERFLOW
Go to Step 8
[END OF IF]

• Step 2: SET TEMP = HEAD
• Step 3: Repeat Step 4 while TEMP -> NEXT != HEAD
• Step 4: SET TEMP = TEMP -> NEXT
• [END OF LOOP]

• Step 5: SET TEMP -> NEXT = HEAD -> NEXT
• Step 6: SET HEAD -> NEXT -> PREV = TEMP
• Step 8: SET HEAD = TEMP -> NEXT

C Function

Output

```1.Append List
2.Delete Node from beginning
3.Exit

Enter the item
12

Node Inserted
1.Append List
2.Delete Node from beginning
3.Exit

Node Deleted
```