1. Калькулятор для двух чисел

#include <iostream>
using namespace std;
int main() {
    double x_1, y_1, r_1; char symbol;
    cout << "Enter first number" << "\n";
    cin >> x_1;
    cout << "Enter second number" << "\n";
    cin >> y_1;
    cout << "List of operations which you can use are +, -, *, /" << "\n" << "What operation do you want to do?" << "\n";
    cin >> symbol;
    if (symbol == '+') {
        r_1 = x_1 + y_1;
        cout << x_1 << "+" << y_1 << "=" << r_1;
    }
    else if (symbol == '-') {
        r_1 = x_1 - y_1;
        cout << x_1 << "-" << y_1 << "=" << r_1;
    }
    else if (symbol == '*') {
        r_1 = x_1 * y_1;
        cout << x_1 << "*" << y_1 << "=" << r_1;
    }
    else if (symbol == '/') {
        if (y_1 == 0) {cout << "Error";}
        else {
            r_1 = x_1 / y_1;
            cout << x_1 << "/" << y_1 << "=" << r_1 << endl;
        }
    }
    else {
        cout << "You didn't introduce operation" << endl;
    }
    return 0;
}