Have you ever wondered how the stack data structure works? This article will explain the Stack data structure, its implementation, and how you can apply it practically. It will also discuss some of its advantages and disadvantages.

What is a Stack?

Stack is a linear data structure that allows adding and removing data in a LIFO ( Last-In , First-Out ) order. To better explain the order, picture a pile of plates stacked over one another in a canteen. You can put a plate onto the top of the pile or take the top plate off. The plate added first is always the one to be removed last.

Basic Stack operations

A Stack implementation must provide at least these operations:

1. push(e): Add item e to the top of the Stack.
2. pop(): To retrieve and remove the item on top of the Stack.
3. peek(): To retrieve the item on top of the Stack without removing it.

Implementing a Stack

To implement a Stack, you can use an Array or a LinkedList as an underlying data structure. Since arrays have a fixed size, if the number of elements inserted into the Stack exceeds the array size, you will need to copy all elements into a bigger array. However, using a LinkedList helps avoid this extra overhead because LinkedLists allocate space as needed.

Using Array as the underlying data structure

push(e) operation algorithm:

• Check if the size limit of the underlying array has been reached
• If it has, copy all elements in the current underlying array to a bigger array
• Insert item in next available index in the underlying array

pop() operation algorithm:

• Retrieve an item from the last filled index in the underlying array and remove the reference to it

peek() operation algorithm:

• Retrieve an item from the last filled index in the underlying array

Using Doubly LinkedList as the underlying data structure

push(e) operation algorithm:

• Add an element to the LinkedList's head

pop() operation algorithm:

• Remove element from the head of the LinkedList

peek() operation algorithm:

• Return element at the head of the LinkedList

Some applications of Stack

The most effortless application of a Stack is to reverse a word. You push a word to a Stack - letter by letter - and then pop letters from the Stack.

There are other popular applications like:

1. The "undo" feature in your text editor
2. Conversion of expressions (Postfix to Prefix, Infix to Postfix etc.)

Some advantages of Stack

• Efficient data management using the LIFO (last in, first out) order
• A Stack automatically cleans up the object. Cleaning up an object means releasing any resources (disk space, main memory, and CPU time) that the object holds.

Some disadvantages of Stack

• Limited memory size: A Stack memory is very limited.
• Random access is not possible: Random access to data is impossible in a Stack.

Conclusion

A Stack is an essential data structure. Understanding its implementation, applications, advantages and disadvantages discussed in this article is vital to use the data structure efficiently.

Reference

github.com/oyekanmiayo/data-structures-all-..