Difference Between Stack and Queue Data Structures

Difference Between Stack and Queue: Stack and Queue are two essential data structures in computer science that aid in data organization and management. It is an important topic to cover for candidates who want to qualify for the GATE Computer Science Exam. Candidates preparing for this exam must know the Difference Between Stack and Queue.

Although Stack and Queue both work towards the same goal, still there are some differences between them.

In this article, we'll look at the differences between Stack and Queue , as well as their similarities.

What is Stack?

Stack is a linear data structure that adheres to the Last-In-First-Out (LIFO) principle, which states that the element inserted last is the first to be deleted. That is, the last piece added to the stack is the first to be withdrawn.

Push (adds an element to the top of the stack) and Pop (removes the topmost element from the stack) are the two basic operations of the stack.

What is a Queue?

A queue is a linear data structure that operates on the First-In-First-Out (FIFO) principle, which states that the element inserted first is the first to be deleted. That is, the first piece added to the queue is the first to be eliminated.

The queue has two major operations: Enqueue (adds an element to the queue's back end) and Dequeue (removes the queue's front element).

Differences Between Stack and Queue

Let's take a closer look at the key difference between Stack and Queue .

• Operation Concept - The most fundamental distinction between Stack and Queue is their operation concept. The Stack concept is Last-In-First-Out (LIFO), whereas the Queue principle is First-In-First-Out (FIFO).
• Order of Elements - In a Stack, element addition occurs at the top, but in a Queue, it occurs at the bottom. Similarly, in Stack, items are removed from the top, but in Queue, they are removed from the front.
• Implementation - A Stack may be constructed using either an array or a linked list, but a Queue can only be done with a linked list. The reason for this is that in a Queue, we require two pointers - front and back.
• Number of Pointers - A Stack has one pointer that points to the top of the stack, but a Queue has two - front and back.
• Operations - Stack makes use of the Push and Pop operations, whereas Queue makes use of the Enqueue and Dequeue operations.
• Capacity - A Stack has a finite capacity, but a Queue may contain an infinite number of pieces.
• Element Access - In Stack, only the top element is accessible, but in Queue, both the front and back components are accessible.
• Memory Efficiency - Because it takes up less space, Stack is more memory efficient than Queue.
• Performance - Stack is quicker than Queue since it just requires one pointer to retrieve the components.
• Algorithm Uses - Stack is employed in algorithms for recursive function calls, expression evaluation, backtracking algorithms, and undo/redo capabilities. Queue, on the other hand, is utilised in algorithms such as breadth-first search, job scheduling, printing jobs, and game programming.
• Components Visibility - In Stack, the top element is always visible, however in Queue, the front element may be hidden if there are too many components.
• Limitations - The stack has a limited capacity, and attempting to push an element while it is full will result in a stack overflow error. Likewise, attempting to pop an element from an empty stack will result in a stack underflow error. Queue does not have such constraints.
• Real-life Analogy - A stack of plates is a good comparison for Stack since we can only add or remove dishes from the top. A queue of people waiting in queue is an analogy for Queue, where the person who joins the queue first is serviced first.
• Application in Data Structures - The Stack is used to construct undo-redo capabilities, whereas the Queue is utilised to implement message queues and priority queues.
• Application Use - Stack is used to build the back and forward buttons in web browsers, whereas Queue is used to implement music and video streaming services.

Similarities Between Stack and Queue

Other than the differences, they have some similarities. Below, you can check the Similarities Between Stack and Queue.

• Stack and Queue are both linear data structures.
• Arrays or linked lists can be used to implement both Stack and Queue.
• In programming, both Stack and Queue are used to handle data.