# What Is Doubly Linked List in Data Structure?

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Heather Bennett

What Is Doubly Linked List in Data Structure?

A doubly linked list is a type of data structure that consists of a sequence of elements called nodes. Each node contains two pointers, one pointing to the previous node and another pointing to the next node in the sequence. This allows for efficient traversal in both directions, forward and backward.

## Basic Structure of a Doubly Linked List

A doubly linked list is typically represented by its head, which points to the first node in the sequence. The last node in the sequence has its next pointer set to null, indicating the end of the list. Similarly, the first node’s previous pointer is set to null, marking the beginning of the list.

To better understand how a doubly linked list works, let’s take a look at its basic structure:

• Node: Each node in a doubly linked list contains two fields: data and two pointers – prev and next.
• Data: The data field stores the actual value or element associated with each node.
• Prev Pointer: The prev pointer points to the previous node in the sequence.
• Next Pointer: The next pointer points to the next node in the sequence.

Doubly linked lists offer several advantages over other types of data structures:

• Bidirectional Traversal: Unlike singly linked lists, which only allow forward traversal, doubly linked lists allow efficient traversal in both directions. This flexibility can be beneficial in various scenarios.
• Insertion and Deletion: Inserting or deleting a node in a doubly linked list is more efficient than in a singly linked list, as it doesn’t require traversing the entire list to reach the desired location. This makes doubly linked lists suitable for applications that involve frequent insertion or deletion operations.
• Reverse Traversal: The prev pointers in a doubly linked list enable easy reverse traversal, which can be useful in certain algorithms or when accessing elements from the end of the list.

## Common Operations on Doubly Linked Lists

Doubly linked lists support various operations to manipulate and access their elements:

• Insertion: Adding a new node to a doubly linked list involves adjusting the prev and next pointers of neighboring nodes to maintain the correct sequence.
• Deletion: Removing a node from a doubly linked list requires updating the prev and next pointers of its neighboring nodes to bridge the gap created by the removal.
• Traversal: Traversing a doubly linked list can be done either forward or backward by following the next and prev pointers of each node.
• Searching: Searching for specific data within a doubly linked list involves iterating through each node until the desired data is found or reaching the end of the list.

### In Conclusion

A doubly linked list is an essential data structure that offers bidirectional traversal and efficient insertion/deletion operations. Its ability to traverse both forward and backward makes it suitable for various applications. Understanding the basic structure and operations of doubly linked lists is crucial for efficient programming and solving complex problems.