ch15/1535ex/Basket2.cc
// if specified number of items are purchased, use discounted price 
if specified number of items are purchased, use discounted price
if specified number of items are purchased use discounted price
double Bulk_item::net_price(size_t cnt) const
{
    if (cnt >= quantity)
        return cnt * (1 - discount) * price;
    else
        return cnt * price;
}
double Bulk_item :: net_price ( size_t cnt ) const { if ( cnt >= quantity ) return cnt * ( 1 - discount ) * price ; else return cnt * price ; }
if specified number of items are purchased, use discounted price
if specified number of items are purchased use discounted price