double load_price()
{
    double price;

    Goods * tempGd = new Goods();

    cin >> price;

    while (!cin)
    {
        cin.clear();
#undef max
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), 'n');
        cout << endl;
        cout << "You didn't enter a number. Do so, please: ";
        cin >> price;
    } // endwhile
    if (!tempGd->set_price(price))
    {
        cout << endl;
        cout << "The price " << red << "must not" << white << " be negative." << endl;
        cout << "Please, insert a new price: ";
        load_price();
    }
    else
    {
        delete tempGd;
        return price;
    }
}

bool Goods::set_price(double price)
{
    if (price> 0)
    {
        priceSingle_ = price;
        priceTotal_ = price* amount_;
        return true;
    }
    return false;
}

return load_price();

#undef max
double load_price()
{
   for(;;) {
      double price;
      cin >> price;
      if (!cin)
      {
         cin.clear();
         std::cin.ignore(std::numeric_limits<std::streamsize>::max(), 'n');
         cout << endl;
         cout << "You didn't enter a number. Do so, please: ";
         continue;
      }
      if (!Goods().set_price(price))
      {
         cout << endl;
         cout << "The price " << red << "must not" << white << " be negative." << endl;
         cout << "Please, insert a new price: ";
         continue;
      }
      return price;
   }
}