double al = scnd_num_min(num1, Oprt);
al = al * (-1);
double ah = scnd_num_max(num1, Oprt);

cout << "Please enter a value within a range of: " << "n" << fixed << al;
cout << " and " << ah << " : ";

double scnd_num_max(double num1, char Oprt)
    {
    double max1 = 9223372036854775807;
    double max2 = 9223372036854775806;
    double min1 = -9223372036854775806;
    switch(Oprt)
    {
    case '+':
        if (num1 <= 0)
            return max1;
        else
            return (max1 - num1);
    case '-':
        if (num1 >= -1)
            return max1;
        else
            return ((max1 - (num1 * (-1)))+1);
    case '*':
        if ((num1 < min1) || (num1 > max2))
            return 1;
        else if (num1 == 0)
            return max2;
        else if (num1 > 0)
            return (max2 / num1);
        else
            return (max2 / (num1 * (-1)));
    case '/':
        return max2;
    }
}