Implementing A Stack Using Array - C# Programming Exercise

// Importing necessary namespace for basic functionalities
using System; // For basic functionalities like Console

// Class that implements a Stack using an array
class Stack
{
    private int[] stackArray; // Array to hold the stack elements
    private int top;          // Index for the top of the stack
    private int capacity;     // Maximum capacity of the stack

    // Constructor to initialize the stack with a given capacity
    public Stack(int capacity)
    {
        this.capacity = capacity;         // Set the stack's maximum capacity
        stackArray = new int[capacity];   // Initialize the array to hold the stack elements
        top = -1;                         // The stack is initially empty, so top is -1
    }

    // Method to add an element to the stack (Push operation)
    public void Push(int element)
    {
        if (top == capacity - 1) // Check if the stack is full
        {
            Console.WriteLine("Stack is full! Cannot push.");
            return;
        }
        stackArray[++top] = element; // Increment top and add the element to the stack
        Console.WriteLine($"Pushed: {element}");
    }

    // Method to remove the top element from the stack (Pop operation)
    public void Pop()
    {
        if (top == -1) // Check if the stack is empty
        {
            Console.WriteLine("Stack is empty! Cannot pop.");
            return;
        }
        int poppedElement = stackArray[top--]; // Get the top element and decrement top
        Console.WriteLine($"Popped: {poppedElement}");
    }

    // Method to display all elements in the stack
    public void DisplayStack()
    {
        if (top == -1) // Check if the stack is empty
        {
            Console.WriteLine("Stack is empty.");
            return;
        }

        Console.WriteLine("Stack contents:");
        for (int i = top; i >= 0; i--) // Display elements from top to bottom
        {
            Console.WriteLine(stackArray[i]);
        }
    }
}

// Main program to demonstrate the Stack functionality
class Program
{
    static void Main(string[] args)
    {
        // Create a stack with a capacity of 5
        Stack stack = new Stack(5);

        // Menu to allow user to interact with the stack
        while (true)
        {
            Console.WriteLine("\nMenu:");
            Console.WriteLine("1. Push an element");
            Console.WriteLine("2. Pop an element");
            Console.WriteLine("3. Display the stack");
            Console.WriteLine("4. Exit");
            Console.Write("Enter your choice: ");
            string choice = Console.ReadLine();

            if (choice == "1")
            {
                // Prompt user to enter an element to push onto the stack
                Console.Write("Enter an element to push: ");
                int element = int.Parse(Console.ReadLine());
                stack.Push(element); // Push the element onto the stack
            }
            else if (choice == "2")
            {
                // Pop an element from the stack
                stack.Pop(); // Pop the top element from the stack
            }
            else if (choice == "3")
            {
                // Display the current stack
                stack.DisplayStack(); // Show the current elements in the stack
            }
            else if (choice == "4")
            {
                // Exit the program
                break;
            }
            else
            {
                // Invalid choice
                Console.WriteLine("Invalid choice. Please try again.");
            }
        }
    }
}