What is a stack in C++ and how is it implemented?

Table of Contents

• Introduction
• Stack Operations
  • 1. Push
  • 2. Pop
  • 3. Top (or Peek)
  • 4. IsEmpty
• Implementation of a Stack in C++
  • Using Arrays
  • Using Linked Lists
• Conclusion

Introduction

A stack is a fundamental data structure used in C++ and other programming languages to manage data in a Last In, First Out (LIFO) manner. In a stack, the most recently added element is the first one to be removed. Stacks are widely used for various applications such as function calls, expression evaluation, and backtracking algorithms. This guide explores the stack data structure, its operations, and provides practical implementation examples in C++.

Stack Operations

A stack supports the following primary operations:

1. Push

Adds an element to the top of the stack.

2. Pop

Removes the element from the top of the stack.

3. Top (or Peek)

Returns the element at the top of the stack without removing it.

4. IsEmpty

Checks whether the stack is empty.

Implementation of a Stack in C++

Using Arrays

You can implement a stack using an array where you maintain a variable to track the top index.

Implementation Example:

Using Linked Lists

A stack can also be implemented using a singly linked list, where each node points to the next node, and the top of the stack is managed by a pointer.

Implementation Example:

Conclusion

Stacks in C++ are essential data structures that can be implemented using arrays or linked lists. Each implementation has its advantages: array-based stacks offer constant time complexity for operations but have a fixed size, while linked-list-based stacks provide dynamic sizing but involve additional memory overhead for pointers. Understanding how to implement and use stacks effectively will enhance your ability to manage data and solve problems efficiently in C++.