问如何使用std::format创建宽度和声明精度(在C++20中)？

EN

      for (size_t k{};k<length;++k)
      {
    
    cout << "Enter the product number:\n";
    cin >> value;
    product.push_back(value);

    cout << "Enter the quantity:\n";
    cin >> value;
    quantity.push_back(value);

    cout << "Enter the unit price($):\n";
    cin >> value;
    price.push_back(value);

}

cout << "Product  Quantity  Perunit($)  Cost($)" << endl;

for (int i = 0; i < product.size(); i++)
{
    cout << format("{:<}{:^15}{:^7}{:^17.2}\n",product[i],
        quantity[i],price[i],(quantity[i]*price[i]));
}