Stack vs Queue: Difference and Comparison

Stacks and Queues are features in programing language that assist the user in solving any arising problems in the program.

Although both stack and queue are vastly categorized under the data structures that are non-primitive, they are different from each other in several aspects.

Key Takeaways

1. Stacks implement a Last-In-First-Out (LIFO) data structure, where the newest element is removed first, while queues follow a First-In-First-Out (FIFO) structure, with the oldest element removed first.
2. In stacks, insertion and removal operations occur at the top, while in queues, insertion occurs at the rear and removal at the front.
3. Stacks are more suitable for situations requiring reversal or backtracking, while queues are better suited for scenarios involving scheduling or maintaining the order of elements.

Stack vs Queue

The difference between Stack and Queue is that, in the case of the stack, the element deletion takes place from one end, and addition of the element takes place in the ordered list itself, known as TOS. On the other hand, in the case of the queue, elements are deleted and inserted from the same end.

The stack can be described as a linear data structure that can be said non-primitive.

From one end, the pre-established element is removed, and new features are added to this ordered list which is known as the TOS or the top of the stack. The stack can exhibit the performance of basic operations such as PUSH and POP.

The queue is also considered as the non-primitive type of linear data structure. It is a gathering of elements that are similar to each other.

It has two ends, rare and front ends, where elements are inserted or deleted, respectively. The queue can perform basic operations such as enqueue and dequeue.

Comparison Table

Parameters for comparison	Stack	Queue
Working principle	The working principle associated with the stack is considered as LIFO or last in the first out type of list.	In this data structure of stack, elements can be inserted using one and deleted using the same end.
Usage of pointers and operations	The number of pointers used in the stack is one. The operations performed in this data structure are push and pop.	The number of pointers used in the queue is two. The operations performed in this data structure are enqueue and dequeue.
Structure	In the case of the queue, the rear end is concerned with the insertion, and the front end is concerned with the deletion of elements.	Unlike queue, the stack data structure is not associated with variants. The implementation associated with it is more straightforward.
Variants	This data structure has variants such as priority queue, circular queue, and doubly-ended queue. Its implementation is comparatively complex.	Examination of an empty condition associated with the stack is Top == – 1. Examination of the complete condition of the stack is Top == Max – 1.
Examination of condition	Examination of the empty condition is Front == -1|| Front ++ Rear + 1 and examination of full condition is Rear == Max – 1.	Examination of the empty condition is Front == -1|| Front ++ Rear + 1, and examination of complete condition is Rear == Max – 1.

What is Stack?

The last element added to the stack will be deleted as insertion or deletion is executed from the top. Due to this purpose, it is known as the last-in-first-out type of list or LIFO.

There are several implementations of the stack, such as undo in the word processor, java virtual machine, a compiler’s parsing, printers’ PostScript language,

web browser’s back button, incorporating function calls in compilers, and others. Implementation of the stack can be done in two manners such as static implementation and dynamic implementation.

Stack in developed in static implementation with the help of arrays.

Though the static implementation is known to be effortless, it permits the declaration of the stack size only while designing the program, after which the verification of length cannot be done.

Static implementation is not considered to have high efficiency associated with memory utilisation. On the other hand, dynamic implementation is also known as linked list representation.

Pointers are used for implementing data structure with stack type.

For example, we may say that when the wrapper of biscuits is torn on one end, the biscuits can be taken out from there (popping), and biscuits can be put back (pushing).

What is Queue?

This is considered FIFO or first in, first out type of list. The queue implementation can be branched into static and dynamic implementation.

In a static implementation, when arrays are used for implementing a queue, and the definite number of elements to be stored in the line should be assured beforehand.

This is done as the array’s size must be assured before processing or designing. The front of the queue comprises the array’s starting, and the rear of the queue’s final location.

The dynamic implementation has a linked representation where the data field is present.

Linked representation’s merit becomes evident when an element is required to get inserted or deleted in the middle of groups comprising other aspects.

The queue can be applied in several ways, such as traffic analysis, data buffers, determination of the number of cashiers required in a supermarket,

allotting requests on shared resources like processors or printers, asynchronous transfer of data, and several others.

For example, we may say that when we wait to get serviced,, we form a queue for obtaining services that can be considered a queue.

Main Differences Between Stack and Queue

1. The working principle of the stack is known to be the LIFO type of list, whereas the working principle of the queue is the FIFO type of list.
2. The usage of pointers in the stack case is one, and in the case of the queue, it is two.
3. In the case of the stack, elements can be inserted and deleted from the same end. In the case of the queue, the rear end is associated with addiction and the front end is associated with elements’ deletion.
4. Stack does not have variants, whereas queue has variants.
5. The stack implementation is simpler, but the queue implementation is more complex than that of the stack.

References

1. https://www.sciencedirect.com/science/article/abs/pii/S0305054818301977
2. https://ieeexplore.ieee.org/abstract/document/8560943/

Last Updated : 11 June, 2023