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Difference Between Stack and Queue Data Structures

Data Structures are fundamental concepts in programming that are crucial for organizing and storing data efficiently in computer memory. Stacks and queues play a significant role. This article provides a detailed comparison between stack and queue data structures, exploring their characteristics, operations, and use cases, which will greatly assist you in your programming tasks.

What is a Stack Data Structure?

A stack is a linear data structure that stores elements in the LIFO(Last In, First Out) order. However, the stack can also be used to store the same type of data in memory.  You can image the stack as the plates where you can only add or remove the topmost plate.

Operations on Stack Data Structure

The primary operation on the stack data structure is here:

• Push: This operation pushes the element on the top of the stack.
• Pop: Removes and returns the top element from the stack.
• Peek or Top: Returns the top element of the stack without removing it from the stack.
• IsEmpty: Checks if the stack is empty or not.
• Size: Returns the number of elements in the stack size.

Use Cases of Stack Data Structure

The stack data structure is used in various applications. Let’s see that application.

• Function Call Management: The stack is heavily used in programming languages for managing function calls. When you call a function, its parameters and local variables are pushed onto the call stack.
• Expression Evaluations: Stack is also used in evaluating arithmetic depression such as infix postfix or prefix notations.
• Browser History: The web browser is also used to implement the back and forward button sting. Each visited webpage is pushed on the stack. When the user clicks “back,” the previous page is popped from the stack.

What is a Queue Data Structure?

A queue is a linear data structure that also follows the first-in-first-out (FIFO) principle. It is similar to a line of people waiting for service, where the person who has been waiting the longest gets served first.

The primary operations associated with a queue data structure are.

• Enqueue: This operation adds an element to the end (rear) of the queue data structure.
• Dequeue: This operation removes the front element from the queue data structure.
• Front (or Peek): Return the front element from the queues without removing it.
• IsEmpty: Checks if the queue is empty or not.
• Size: Returns the number of elements in the queue data structure.

Use Cases of Queue Data Structure

The following applications are used in the queue data structure.

• Task Scheduling: Operating systems are used to manage the tasks and processes using the Queue.
• Breadth First Search (BFS):  In graph traversal algorithms queues help in exploring nodes level by level.
• Buffering: Queue is also used where data is transferred asynchronously, such as IO buffers and print spooling.

Difference Between Stack and Queue Data Structures

The following table differentiates the Stack and Queue Data structure:

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