C++ Program to Implement Stack using array

// Include necessary libraries
#include <iostream>
using namespace std;

// Define Stack class
class Stack {
    // Pointer to an array that stores elements of the stack
    int* arr;
    // Index of the top element in the stack
    int top;
    // Maximum size of the stack
    int capacity;

public:
    // Constructor to initialize the stack
    Stack(int size)
    {
        // Allocate memory for the stack
        arr = new int[size];
        // Set the maximum size of the stack
        capacity = size;
        // Initialize the top of the stack as -1 indicating
        // the stack is empty
        top = -1;
    }

    // Destructor to deallocate memory
    ~Stack() { delete[] arr; }

    // Function to add an element x in the stack
    void push(int x)
    {
        // Check if the stack is full
        if (isFull()) {
            cout << "Overflow\n";
            return;
        }
        cout << "Pushing " << x << "\n";
        // Add element and increment top
        arr[++top] = x;
    }

    // Function to remove an element from the stack
    int pop()
    {
        // Check if the stack is empty
        if (isEmpty()) {
            cout << "Underflow\n";
            return -1;
        }
        // Remove element and decrement top
        return arr[top--];
    }

    // Function to return the top element of the stack
    int peek()
    {
        if (!isEmpty())
            return arr[top];
        else
            return -1;
    }

    // Function to return if the stack is empty
    bool isEmpty() { return top == -1; }

    // Function to return if the stack is full
    bool isFull() { return top == capacity - 1; }
};

// Main function
int main()
{
    // Create a stack of size 3
    Stack stack(3);

    // Push elements into the stack
    stack.push(10);
    stack.push(20);
    stack.push(30);

    // Print the top element of the stack
    cout << "The top element is " << stack.peek() << endl;
    // Pop an element from the stack and print it
    cout << "Popping " << stack.pop() << endl;
    // Print the top element of the stack
    cout << "The top element is " << stack.peek() << endl;

    // Pop all elements from the stack
    stack.pop();
    stack.pop();

    // Check if the stack is empty and print the result
    if (stack.isEmpty()) {
        cout << "The stack is empty" << endl;
    }
    else {
        cout << "The stack is not empty" << endl;
    }

    return 0;
}