A simple calculator program that I wrote using object-oriented programming using C++ programming language.

#include <iostream>

class Calculator {
public:
    double add(double a, double b) {
        return a + b;
    }

    double subtract(double a, double b) {
        return a - b;
    }

    double multiply(double a, double b) {
        return a * b;
    }

    double divide(double a, double b) {
        if (b != 0) {
            return a / b;
        } else {
            std::cout << "Error: Division by zero is not allowed." << std::endl;
            return 0.0;
        }
    }
};

int main() {
    double num1, num2;
    char operation;

    std::cout << "\tMy Simple Calculator Using OOP in  C++\n\n";
    std::cout << "\tEnter two numbers: ";
    std::cin >> num1 >> num2;

    std::cout << "\tEnter select an operator (+, -, *, /): ";
    std::cin >> operation;

    Calculator calc;

    double result;

    switch (operation) {
        case '+':
            result = calc.add(num1, num2);
            break;
        case '-':
            result = calc.subtract(num1, num2);
            break;
        case '*':
            result = calc.multiply(num1, num2);
            break;
        case '/':
            result = calc.divide(num1, num2);
            break;
        default:
            std::cout << "I\tnvalid operator." << std::endl;
            return 1;
    }

    std::cout << "\n\tThe Result is " << result << "." <<std::endl;
    std::cout << "\n\n\tEnd of Program\n";
    return 0;
}