C++prime 第十五章的程序总结（购物车）

来源：互联网发布：局域网网络电话机编辑：程序博客网时间：2024/05/16 07:13

商品类

#ifndef CP5_EX15_30_QUOTE_H#define CP5_EX15_30_QUOTE_H#include <string>#include <iostream>inline namespace EX30 {    using std::string;    using std::ostream; using std::endl;    using std::move;class Quote {public:    Quote() = default;    Quote(string const& b, double p) : bookNo(b), price(p) { }    Quote(const Quote&) = default;    Quote(Quote&&) = default;    Quote& operator=(const Quote&) = default;    Quote& operator=(Quote&&) = default;    virtual Quote* clone() const & { return new Quote(*this); }    virtual Quote* clone() && { return new Quote(move(*this)); }    string isbn() const { return bookNo; }    virtual double net_price(size_t n) const { return n * price; }    virtual ~Quote() = default;private:    string bookNo;protected:    double price = 0.0;};class Bulk_quote : public Quote {public:    Bulk_quote() = default;    Bulk_quote(const string &b, double p, size_t q, double d) : Quote(b, p), min_qty(q), discount(d) {}    Bulk_quote(const Bulk_quote& lhs) : Quote(lhs), min_qty(lhs.min_qty), discount(lhs.discount) {}    Bulk_quote(Bulk_quote&& rhs) noexcept : Quote(move(rhs)), min_qty(move(rhs.min_qty)), discount(move(rhs.discount)) {}    Bulk_quote& operator=(const Bulk_quote& lhs)    { Quote::operator=(lhs); min_qty = lhs.min_qty; discount = lhs.discount; return *this; }    Bulk_quote& operator=(Bulk_quote&& rhs) noexcept    { Quote::operator=(move(rhs)); min_qty = move(rhs.min_qty), discount = move(rhs.discount); return *this; }    virtual Bulk_quote* clone() const & { return new Bulk_quote(*this); }    virtual Bulk_quote* clone() && { return new Bulk_quote(std::move(*this)); }    virtual double net_price(std::size_t cnt) const override {        if (cnt >= min_qty) return cnt * (1 - discount) * price;        else return cnt * price;    }protected:    size_t min_qty = 0;    double discount = 0.0;};double print_total(ostream& os, Quote const& item, size_t n) {    double ret = item.net_price(n);    os << "ISBN: " << item.isbn() << " # sold: " << n << " total due: " << ret << endl;    return ret;}}

购物车类

#include <memory>#include <set>#include "ex15_30_Quote_Bulk_quote.h"namespace EX30 {    using std::shared_ptr;    class Basket {    public:        Basket() = default;        void add_item(const Quote &sale) { items.insert(shared_ptr<Quote>(sale.clone())); }        void add_item(Quote &&sale) { items.insert(shared_ptr<Quote>(std::move(sale).clone())); }        inline double total_receipt(std::ostream&) const;    private:        static bool compare(const shared_ptr<Quote> &lhs, const shared_ptr<Quote> &rhs) {            return lhs->isbn() < rhs->isbn();        }        std::multiset<shared_ptr<Quote>, decltype(compare)*> items{compare};    };    inline double Basket::total_receipt(std::ostream &os) const {        auto sum = 0.0;        for (auto iter = items.cbegin(); iter != items.cend(); iter = items.upper_bound(*iter)) {            sum += print_total(os, **iter, items.count(*iter));        }        os << "Total Sale: " << sum << std::endl;        return sum;    }}

阅读全文

0 0