C++primer 练习15.15

// 15_15.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>
#include<string>
using namespace std;

class Quote
{
public:
Quote() = default;
Quote(const string &book,double p):bookNo(book),price(p){}
const string& isbn()const { return bookNo; }
virtual double net_price(size_t n)const
{
return n*price;
}
private:
string bookNo;
protected:
double price = 0.0;
};

class Dis_Quote :public Quote
{
public:
Dis_Quote() = default;
Dis_Quote(const string &book,double p,size_t n,double d):Quote(book,p),quantity(n),discount(d){}
virtual double net_price(size_t n)const = 0;
protected:
size_t quantity = 0;
double discount = 0.0;
};

class Bulk_Quote :public Dis_Quote
{
public:
Bulk_Quote() = default;
Bulk_Quote(const string &book,double p,size_t n,double d):Dis_Quote(book,p,n,d){}
virtual double net_price(size_t n)const override
{
if (n > quantity)
return n*(1 - discount)*price;
else
return n*price;
}
};

class Exercise_Quote :public Dis_Quote
{
public:
Exercise_Quote() = default;
Exercise_Quote(const string &book,double p,size_t n,double d):Dis_Quote(book,p,n,d){}
virtual double net_price(size_t n)const override
{
if (n <= quantity)
return n*(1 - discount)*price;
else
return quantity*(1 - discount)*price + (n - quantity)*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()
{
Quote q1("lidandan", 5);
Bulk_Quote q2("lidandan", 5, 9, 0.1);
Exercise_Quote q3("lidandan", 5, 9, 0.1);
//Dis_Quote q4;
print_total(cout, q1, 10);
print_total(cout, q2, 10);
print_total(cout, q3, 10);
return 0;
}