C Programming – Lesson 17: Data Structures (Part 1)

[Audio] Welcome everyone. Today we're starting our first lesson on data structures in C. We're going to look at what data structures are, why they matter, and how we build them using pointers and structs. We'll also introduce some of the most common structures you'll see in computer science: linked lists, stacks, queues, trees, and hash tables..

[Audio] So first, what exactly is a data structure? It's simply a way to organize and store data so we can access it efficiently. Good data structures help us write faster programs, keep things organized, and design algorithms that scale well as our data grows..

[Audio] In C, pointers and structs are the foundation of almost every complex data structure. Pointers let us connect pieces of memory together dynamically, and structs let us group related data. Together, they give us the flexibility to build anything from simple lists to advanced trees and hash tables..

[Audio] Let's start with linked lists. A linked list is a sequence of nodes, where each node stores some data and a pointer to the next node. Unlike arrays, linked lists can grow and shrink easily because each node is allocated dynamically..

[Audio] Here's what a linked list node looks like in C. We have a struct that stores an integer and a pointer to the next node. Implementing a linked list usually involves writing functions like 'create node', 'insert node', 'copy node', and 'destroy node' to manage memory safely..

[Audio] Next up are stacks. A stack follows the 'LIFO' rule—Last In, First Out. That means the most recent item you add is the first one you remove. The main operations are push, pop, and peek or top. Stacks show up everywhere in programming, from undo systems to expression evaluation..

[Audio] A good way to picture a stack is to imagine a stack of boxes. You can only add a box on top, and you can only remove the top box. You can also peek at the top box without removing it. That's exactly how a stack works in code..

[Audio] Queues work differently—they follow 'FIFO', First In, First Out. The first item added is the first one removed. The main operations are enqueue, dequeue, front, and rear. Queues are great for scheduling tasks or managing events in order..

[Audio] A queue is like a line at a coffee shop. New customers join at the back, and the barista serves the person at the front. That's enqueue and dequeue. Front shows you who's next, and rear shows you who's last in line..

[Audio] Trees are hierarchical structures. Instead of a simple sequence, each node can have children. A binary tree, for example, has up to two children per node. Trees are incredibly useful for organizing data in a way that allows fast searching and sorting..

[Audio] Here's an example of a tree node. It stores data and has pointers to a left and right child. Implementing trees usually involves functions like 'create node', 'insert node', 'traverse tree', and 'destroy tree'. Trees form the basis of many advanced algorithms..

[Audio] Hash tables store key-value pairs and use a hash function to determine where each item goes. This allows extremely fast lookup times—often close to constant time. Hash tables are used everywhere, from databases to compilers to operating systems..

[Audio] A hash table is like a row of numbered mailboxes. The key tells you exactly which mailbox to check. Inserting means putting a letter in the right box, searching means checking that box, and deleting means removing the letter. It's a simple idea with powerful performance benefits..

[Audio] All of these data structures rely on the same core ideas: pointers, structs, and dynamic memory. Once you understand how these pieces work together, you can build almost any structure you need..

[Audio] And finally, think about this: which structure would you use for undo operations? For managing print jobs? For fast lookup of employee records? Each structure has strengths and weaknesses, and choosing the right one is a big part of being a good programmer..