Introduction to Stack

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In the realm of computer science and programming, understanding data structures is fundamental. One such essential data structure is the stack. In this article, we’ll delve into what stacks are, how they work, their operations, and their applications in programming.

What is a Stack?

A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. Imagine a stack of plates in a cafeteria; you can only take the top plate off the stack. Similarly, in a stack data structure, elements can only be added or removed from the top.

How Does a Stack Work?

A stack has two primary operations: push and pop.

  • Push: Adds an element to the top of the stack.
  • Pop: Removes the top element from the stack.

Additionally, stacks typically support other operations like peek (to view the top element without removing it) and isEmpty (to check if the stack is empty).

Stack Implementation:

Stacks can be implemented using arrays or linked lists.

  • Array Implementation: In this approach, a fixed-size array is used to store the stack elements. Push and pop operations modify the top index of the array.
  • Linked List Implementation: Here, a linked list is used to implement the stack. Each node in the linked list represents an element, and the top of the stack is the head of the list.

Stack Operations:

Let’s look at the stack operations in detail:

  • Push: Adds an element to the top of the stack. The new element becomes the top element, and the stack size increases by one.
  • Pop: Removes the top element from the stack. The element is returned (or simply removed), and the stack size decreases by one.
  • getTop: Returns the top element of the stack without removing it.
  • isEmpty: Checks if the stack is empty. Returns true if the stack is empty, and false otherwise.

Applications of Stacks:

Stacks find applications in various areas of computer science and programming, including:

  • Function Call Stack: Used to manage function calls and local variables in programming languages.
  • Expression Evaluation: Used to evaluate arithmetic expressions, infix-to-postfix conversion, and solving postfix expressions.
  • Undo Mechanism: Supports the undo operation in text editors and graphic design software.
  • Backtracking: Used in algorithms like depth-first search (DFS) to explore all possible paths in a graph.


In conclusion, stacks are simple yet powerful data structures that play a crucial role in many programming tasks. Understanding how stacks work and their applications can significantly enhance a programmer’s problem-solving abilities. Whether you’re a beginner or an experienced programmer, mastering stacks is essential for building efficient and robust software systems.


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