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：