Sales_item.h不是C++自帶的，需要自己安裝，這個庫作者已經寫好了,
Sales_item.h 頭文件代碼如下：

#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(std::istream &is){ is >> *this;}friend std::istream& operator>>(std::istream &,Sales_item &);friend std::ostream& operator<<(std::ostream &,const Sales_item &); public:Sales_item & operator+=(const Sales_item&); public:double avg_price() const;bool same_isbn(const Sales_item &rhs)const{return isbn == rhs.isbn;}Sales_item():units_sold(0),revenue(0.0){} public:std::string isbn;unsigned units_sold;double revenue; };using std::istream; using std::ostream; Sales_item operator+(const Sales_item &,const Sales_item &);inline bool operator==(const Sales_item &lhs,const Sales_item &rhs){return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue && lhs.same_isbn(rhs); }inline bool operator!=(const Sales_item &lhs,const Sales_item &rhs){return !(lhs == rhs); }inline Sales_item & Sales_item::operator +=(const Sales_item &rhs){units_sold += rhs.units_sold;revenue += rhs.revenue;return *this; }inline Sales_item operator+(const Sales_item &lhs,const Sales_item &rhs){Sales_item ret(lhs);ret += rhs;return ret; }inline istream& operator>>(istream &in,Sales_item &s){double price;in >> s.isbn >> s.units_sold >> price;if(in)s.revenue = s.units_sold * price;elses = Sales_item();return in; }inline ostream& operator<<(ostream &out,const Sales_item &s){out << s.isbn << "\t" <<s.units_sold << "\t" << s.revenue << "\t" << s.avg_price();return out; }inline double Sales_item::avg_price() const{if(units_sold)return revenue/units_sold;elsereturn 0; } #endif

注意，Sales_item.h的儲存路徑要和源代碼的儲存路徑一致。這樣，源代碼的頭文件才可以訪問這個類。

如何安裝頭文件？

DevC++如何安裝自定義頭文件并使用

總結

以上是生活随笔為你收集整理的《C++ Primer》第一章的 Sales_item.h头文件源码的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。