《C++ Primer》第一章的 Sales_item.h头文件源码
Sales_item.h 头文件代码如下：#ifndef SALESITEM_H#define SALESITEM_H#include <iostream>#include <string> class Sales_item{public: Sales_item(const std::string &book):isbn(book),units_sold(0),revenue(0.0){} Sales_item(
