Basket.cpp
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上传日期:2022-06-29
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书籍源码
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Visual C++
- /*
- * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
- * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
- * copyright and warranty notices given in that book:
- *
- * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
- *
- *
- * "The authors and publisher have taken care in the preparation of this book,
- * but make no expressed or implied warranty of any kind and assume no
- * responsibility for errors or omissions. No liability is assumed for
- * incidental or consequential damages in connection with or arising out of the
- * use of the information or programs contained herein."
- *
- * Permission is granted for this code to be used for educational purposes in
- * association with the book, given proper citation if and when posted or
- * reproduced.Any commercial use of this code requires the explicit written
- * permission of the publisher, Addison-Wesley Professional, a division of
- * Pearson Education, Inc. Send your request for permission, stating clearly
- * what code you would like to use, and in what specific way, to the following
- * address:
- *
- * Pearson Education, Inc.
- * Rights and Contracts Department
- * 75 Arlington Street, Suite 300
- * Boston, MA 02216
- * Fax: (617) 848-7047
- */
- #include "Basket.h"
- #include <algorithm>
- using std::multiset; using std::map; using std::pair; using std::size_t;
- using std::string; using std::ostream; using std::endl; using std::min;
- using std::cout;
- // debugging routine to check contents in a Basket
- void Basket::display(ostream &os) const
- {
- os << "Basket size: " << items.size() << endl;
- // print each distinct isbn in the Basket along with
- // count of how many copies are ordered and what their price will be
- // upper_bound returns an iterator to the next item in the set
- for (const_iter next_item = items.begin();
- next_item != items.end();
- next_item = items.upper_bound(*next_item))
- {
- // we know there's at least one element with this key in the Basket
- os << (*next_item)->book() << " occurs "
- << items.count(*next_item) << " times"
- << " for a price of "
- << (*next_item)->net_price(items.count(*next_item))
- << endl;
- }
- }
- void print_total(ostream &, const Item_base&, size_t);
- // calculate and print price for given number of copies, applying any discounts
- void print_total(ostream &os,
- const Item_base &item, size_t n)
- {
- os << "ISBN: " << item.book() // calls Item_base::book
- << "tnumber sold: " << n << "ttotal price: "
- // virtual call: which version of net_price to call is resolved at run time
- << item.net_price(n) << endl;
- }
- double Basket::total() const
- {
- double sum = 0.0; // holds the running total
- for (const_iter iter = items.begin();
- iter != items.end();
- iter = items.upper_bound(*iter))
- {
- // we know there's at least one element with this key in the Basket
- print_total(cout, *(iter->p), items.count(*iter));
- // virtual call to net_price applies appropriate discounts, if any
- sum += (*iter)->net_price(items.count(*iter));
- }
- return sum;
- }
- // use-counted assignment operator; use is a pointer to a shared use count
- Sales_item&
- Sales_item::operator=(const Sales_item &rhs)
- {
- ++*rhs.use;
- decr_use();
- p = rhs.p;
- use = rhs.use;
- return *this;
- }
- // if specified number of items are purchased, use discounted price
- double Bulk_item::net_price(size_t cnt) const
- {
- if (cnt >= min_qty)
- return cnt * (1 - discount) * price;
- else
- return cnt * price;
- }
- // use discounted price for up to a specified number of items
- // additional items priced at normal, undiscounted price
- double Lim_item::net_price(size_t cnt) const
- {
- size_t discounted = min(cnt, max_qty);
- size_t undiscounted = cnt - discounted;
- return discounted * (1 - discount) * price
- + undiscounted * price;
- }