Exer15_01_Quote.h

#ifndef QUOTE_H
#define QUOTE_H
#include <cstddef>
#include <iostream>
#include <string>
class Quote {
public:
    Quote() = default;
    Quote(const std::string &book, double sales_price) : bookNo(book), price(sales_price) {}
    std::string isbn() const { return bookNo; }
    // return the total sales price for the specified number of items
    // derived class will override and apply different discount algorithms
    virtual double net_price(std::size_t n) const
        { return n * price; }
    virtual ~Quote() = default; // dynamic binding for the destructor
private:
    std::string bookNo; // ISBN number of this item
protected:
    double price = 0.0; // normal, undiscounted price
};
// calculate and print the price for the given number of copies, applying any discount
double print_total(std::ostream &os, const Quote &item, std::size_t n)
{
    // depending on the type of the object bound to the item parameter
    // calls either Quote::net_price or Bulk_quote::net_price
    double ret = item.net_price(n);
    os << "ISBN: " << item.isbn() // calls Quote::isbn
       << " # sold: " << n << " total due: " << ret << std::endl;
    return ret;
}
#endif