Queue & Circular Queue in C++ | FIFO, Enqueue, Dequeue & Wrap-Around Explained

In this video, I explain Queue and Circular Queue data structures and demonstrate how they can be implemented using a fixed-size array in C++. I begin with the basic FIFO (First In, First Out) principle and explain how the FRONT and REAR positions are used to manage elements in a Queue. I then demonstrate the main Queue operations, including Enqueue and Dequeue, along with important conditions such as isEmpty(), isFull(), Queue Overflow, and Queue Underflow. I also use a real-life checkout-line example to make the FIFO concept easier to understand. An important part of this presentation is understanding the limitation of a linear array-based Queue. When REAR reaches the final array position, empty spaces created near the beginning may not be reused efficiently in a simple linear implementation. This leads into the concept of a Circular Queue, where REAR can wrap around and reuse available positions instead of repeatedly shifting elements. I also explain how circular movement works using the modulo operation: (rear + 1) % SIZE Using a Queue capacity of 5, I demonstrate how REAR can move from index 4 back to index 0. In my example, after removing 15 and 25, the values 65 and 75 reuse indexes 0 and 1, while the logical Queue order remains 35 → 45 → 55 → 65 → 75. Topics covered in this video: • Queue and FIFO principle • FRONT and REAR • Enqueue and Dequeue • isEmpty() and isFull() • Queue Overflow and Underflow • Limitation of a Linear Queue • Circular Queue concept • Wrap-around operation • Modulo % calculation • Linear Queue vs. Circular Queue • C++ Circular Queue implementation and demonstration Through this assignment, I learned why a Circular Queue can use a fixed-size array more efficiently and how FRONT and REAR work together to maintain FIFO order even after wrap-around. I would like to sincerely thank Professor Victor Govindaswamy for his guidance throughout this course. His classroom explanations, examples, quizzes, and programming exercises have helped me understand Data Structures from both the theoretical and practical sides. Working through these concepts step by step has helped me become more confident in understanding how data structures work in actual C++ programs. #DataStructures #ComputerScience #CPlusPlus #Programming #Algorithms #Queue #CircularQueue #FIFO #CppProgramming #GitHub