Linked Lists in C Explained Clearly

What is a Linked List?

A linked list is a dynamic data structure with elements called nodes that contain some data and a reference (or pointer) to the next node in the sequence.

Unlike arrays, elements don't have to be stored in a fixed, continuous block of memory. They can dynamically grow or shrink as needed without allocating a contiguous block of memory like arrays.

How Useful are Linked Lists?

They are useful for implementing various data structures and algorithms as they offer efficient insertion and deletion operations, especially when elements need to be added or removed frequently from the middle of the list.

The only disadvantage is that it requires traversing through the list from the beginning when accessing an element, unlike arrays that are efficient for random access.

They are fundamental data structures used for tasks like managing memory allocation, implementing abstract data types (e.g. stacks, queues), and representing complex data relationships.

Basic Types of Linked Lists in C

1. Singly Linked List

Each nodes contains data and a pointer/reference to the next node in the sequence. It forms a unidirectional chain where traversal is possible only in one direction, usually from the head to the end.

2. Doubly Linked List

Each node contains data and two pointers/references: one points to the next node, and the other points to the previous node. This is bidirectional connectivity which allows traversal in both forward and backward directions.

3. Circular Linked List

The last node's pointer points back to the head node instead of NULL, creating a circular structure. This means the traversal can start from any node and loop back to the beginning.

4. Doubly Circular Linked List

This combines the features of doubly linked and circular lists. The nodes point to both the next and previous in a circular fashion.
They offer maximum flexibility for traversal and operations in both directions.

How To Use Linked Lists in C

1. Define the node structure, which holds the data and the pointer
2. Create a header pointer, which points to the first node in the list
3. Add/remove nodes by allocating memory for new nodes and adjusting pointers to link them in and out
4. Traverse the list by following the pointers from node to node to access data.