Stack.java

package OOPSC26CS070;

import java.util.Scanner;

class Stack {
    int stack[] = new int[5];
    int top;

    // No-argument constructor
    Stack() {
        top = -1;
    }

    // Push operation
    void push(int value) {
        if (top == stack.length - 1) {
            System.out.println("Stack Overflow");
        } else {
            top++;
            stack[top] = value;
            System.out.println(value + " pushed into stack");
        }
    }

    // Pop operation
    void pop() {
        if (top == -1) {
            System.out.println("Stack Underflow");
        } else {
            System.out.println(stack[top] + " popped from stack");
            top--;
        }
    }

    // Display operation
    void display() {
        if (top == -1) {
            System.out.println("Stack is Empty");
        } else {
            System.out.println("Stack Elements:");
            for (int i = top; i >= 0; i--) {
                System.out.println(stack[i]);
            }
        }
    }

    // Peek operation
    void peek() {
        if (top == -1) {
            System.out.println("Stack is Empty");
        } else {
            System.out.println("Top element = " + stack[top]);
        }
    }
}

public class StackDemo {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        Stack s = new Stack();
        int choice, value;

        do {
            System.out.println("\n1. Push");
            System.out.println("2. Pop");
            System.out.println("3. Peek");
            System.out.println("4. Display");
            System.out.println("5. Exit");
            System.out.print("Enter your choice: ");
            choice = sc.nextInt();

            switch (choice) {
                case 1:
                    System.out.print("Enter value: ");
                    value = sc.nextInt();
                    s.push(value);
                    break;

                case 2:
                    s.pop();
                    break;

                case 3:
                    s.peek();
                    break;

                case 4:
                    s.display();
                    break;

                case 5:
                    System.out.println("Program Ended");
                    break;

                default:
                    System.out.println("Invalid Choice");
            }

        } while (choice != 5);

        sc.close();
    }
}