Feature of this programm: 1) Division by zero isn't possible. 2) You've the opportunity to resume working with calculator.

Calculator v2 using class C++.cpp

#include <iostream>
#include <Windows.h>
using namespace std;

class calculator
{
private:
	float answer;

public:
	void strokeUP()   //stars appear at the beginning for beauty.
	{
		for (int i = 1; i < 51; i++)
		{
			cout << "*";
			Sleep(4.5);
		}
		cout << endl;
	}

	void Body() 
	{
		cout << "What function do u wanna use? " << endl;
		cout << "1 - Addition " << endl;
		cout << "2 - Subtraction " << endl;
		cout << "3 - Multiplication " << endl;
		cout << "4 - Division " << endl;
		cout << "Input: ";
	}

	void enter_first_number_text()
	{
		cout << "Please enter first number: ";
	}

	void enter_second_number_text()
	{
		cout << "Please enter second number: ";
	}
	
	void animation() //animation of data reading.
	{
		for (int i = 1; i < 101; i++)
		{
			system("cls");
			cout << "Loading: " << i << "%" << endl;
		}
	}

	int Addition(float firstN, float secondN)
	{
		answer = firstN + secondN;
		return answer;
	}

	int Subtraction(float firstN, float secondN)
	{
		answer = firstN - secondN;
		return answer;
	}

	int Multiplication(float firstN, float secondN)
	{
		answer = firstN * secondN;
		return answer;
	}

	int Division(float firstN, float secondN)
	{
		if (secondN == 0)
		{
			cout << "Division by zero isn't possible";
		}
		else
		{
			answer = firstN / secondN;
		}
		return answer;
	}
};

int main()
{
	int action;
	float firstN, secondN;
	char returnToAction='y';
	calculator calc;

	do // we can resume work with calculator.
	{
		calc.strokeUP();
		calc.Body();

		cin >> action;
		cout << endl;

		switch (action)
		{
		case 1:
		{
			calc.enter_first_number_text();
			cin >> firstN;
			calc.enter_second_number_text();
			cin >> secondN;
			calc.animation();
			cout << "Result: " << firstN << " + " << secondN << " = ";
			cout << calc.Addition(firstN, secondN);
			cout << endl;
			break;
		}

		case 2:
		{
			calc.enter_first_number_text();
			cin >> firstN;
			calc.enter_second_number_text();
			cin >> secondN;
			calc.animation();
			cout <<"Recult: "<< firstN << " - " << secondN << " = ";
			cout << calc.Subtraction(firstN, secondN);
			cout << endl;
			break;
		}

		case 3:
		{
			calc.enter_first_number_text();
			cin >> firstN;
			calc.enter_second_number_text();
			cin >> secondN;
			calc.animation();
			cout << "Result: " << firstN << " * " << secondN << " = ";
			cout << calc.Multiplication(firstN, secondN);
			cout << endl;
			break;
		}

		case 4:
		{
			calc.enter_first_number_text();
			cin >> firstN;
			calc.enter_second_number_text();
			cin >> secondN;
			calc.animation();
			cout << "Result: " << firstN << " / " << secondN << " = ";
			cout << calc.Division(firstN, secondN);
			cout << endl;
			break;
		}

		default:
			cout << "Invalid Input..." << endl;
		}

		cout << "Would u like to continue working with calculator? (y/n): ";
		cin >> returnToAction;
		cout << endl;

	} while (returnToAction == 'Y' || returnToAction == 'y'); // condition of resuming work with calculator.

	system("pause");
	return 0;
}