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C++ Primer（第5版） 练习 15.28

练习 15.28 定义一个存放Quote对象的vector，将Bulk_quote对象传入其中。计算vector中所有元素总的net_price。

环境：Linux Ubuntu（云服务器）

工具：vim

代码块：

/*************************************************************************> File Name: ex15.28.cpp> Author: > Mail: > Created Time: Tus 25 Jul 2024 09:13:44 AM CST************************************************************************/#include<iostream>
#include<vector>
using namespace std;class Quote{public:Quote() = default;Quote(const std::string &book, double sales_price): bookNo(book), price(sales_price) {}std::string isbn() const { return bookNo; }virtual double net_price(std::size_t n) const { return n * price; }virtual ~Quote() = default;private:std::string bookNo;protected:double price = 0.0;
};class Disc_quote: public Quote{public:Disc_quote() = default;Disc_quote(const std::string &book, double price, std::size_t qty, double disc): Quote(book, price), quantity(qty), discount(disc) {}double net_price(std::size_t) const = 0;protected:std::size_t quantity = 0;double discount = 0.0;
};class Bulk_quote: public Disc_quote{public:Bulk_quote() = default;Bulk_quote(const std::string& book, double price, std::size_t qty, double disc): Disc_quote(book, price, qty, disc) {}double net_price(std::size_t) const override;
};double Bulk_quote::net_price(size_t cnt) const{if (cnt >= quantity){return cnt * (1 - discount) * price;}else{return cnt * price;}
}double print_total(ostream &os, const Quote &item, size_t n){double ret = item.net_price(n);os<<"ISBN: "<<item.isbn()<<" # sold: "<<n<<" total due: "<<ret<<endl;return ret;
}int main(){vector<Quote> basket = {Bulk_quote("0-101-13456-X", 10, 10, 0.5), Bulk_quote("0-102-34567-Y", 15, 20, 0.5), Bulk_quote("0-103-32467-X", 5, 30, 0.5)};double total_price = 0.0;for(const auto &b : basket){total_price += b.net_price(15);}cout<<total_price<<endl;return 0;
}

运行结果显示如下：