Writing a Stack in C++

A stack is a fundamental data structure that operates on the principle of Last In, First Out (LIFO). This means that the last element added to the stack is the first one to be removed. Stacks are widely used in programming for tasks like expression evaluation, backtracking, and function call management.

Core Operations

A stack typically supports the following operations:

1. Push: Add an element to the top of the stack.
2. Pop: Remove the top element from the stack.
3. Peek/Top: View the top element without removing it.
4. IsEmpty: Check if the stack is empty.

Implementation in C++

Here is an example of how you can implement a stack in C++ using arrays:

1#include <iostream>
2#define MAX 1000
3
4class Stack {
5private:
6    int top;
7    int arr[MAX]; // Array to store stack elements
8
9public:
10    Stack() { top = -1; } // Constructor to initialize stack
11
12    bool push(int x) {
13        if (top >= (MAX - 1)) {
14            std::cout << "Stack Overflow\n";
15            return false;
16        } else {
17            arr[++top] = x;
18            return true;
19        }
20    }
21
22    int pop() {
23        if (top < 0) {
24            std::cout << "Stack Underflow\n";
25            return -1;
26        } else {
27            return arr[top--];
28        }
29    }
30
31    int peek() {
32        if (top < 0) {
33            std::cout << "Stack is Empty\n";
34            return -1;
35        } else {
36            return arr[top];
37        }
38    }
39
40    bool isEmpty() {
41        return (top < 0);
42    }
43};
44
45int main() {
46    Stack s;
47    s.push(10);
48    s.push(20);
49    s.push(30);
50    std::cout << s.pop() << " popped from stack\n";
51    std::cout << "Top element is " << s.peek() << "\n";
52    return 0;
53}

Advantages of Using Stacks

• Simplicity: Easy to implement and use.
• Efficiency: Operations like push and pop are performed in constant time, O(1).
• Versatility: Useful in various applications like undo mechanisms, parsing expressions, and more.

By implementing a stack in C++, you gain a deeper understanding of how this data structure works and its importance in computer science.