<C++ Primer_5th>第一章用到的头文件<Sales_item.h>
2017-09-30 09:37
621 查看
//头文件:Sales_item.h /* * This file contains code from "C++ Primer, Fifth Edition", by Stanley B. * Lippman, Josee Lajoie, and Barbara E. Moo, and is covered under the * copyright and warranty notices given in that book: * * "Copyright (c) 2013 by Objectwrite, Inc., Josee Lajoie, and Barbara E. Moo." * * * "The authors and publisher have taken care in the preparation of this book, * but make no expressed or implied warranty of any kind and assume no * responsibility for errors or omissions. No liability is assumed for * incidental or consequential damages in connection with or arising out of the * use of the information or programs contained herein." * * Permission is granted for this code to be used for educational purposes in * association with the book, given proper citation if and when posted or * reproduced.Any commercial use of this code requires the explicit written * permission of the publisher, Addison-Wesley Professional, a division of * Pearson Education, Inc. Send your request for permission, stating clearly * what code you would like to use, and in what specific way, to the following * address: * * Pearson Education, Inc. * Rights and Permissions Department * One Lake Street * Upper Saddle River, NJ 07458 * Fax: (201) 236-3290 */ /* This file defines the Sales_item class used in chapter 1. * The code used in this file will be explained in * Chapter 7 (Classes) and Chapter 14 (Overloaded Operators) * Readers shouldn't try to understand the code in this file * until they have read those chapters. */ #ifndef SALESITEM_H // we're here only if SALESITEM_H has not yet been defined #define SALESITEM_H //#include "Version_test.h" // Definition of Sales_item class and related functions goes here #include <iostream> #include <string> class Sales_item { // these declarations are explained section 7.2.1, p. 270 // and in chapter 14, pages 557, 558, 561 friend std::istream& operator>>(std::istream&, Sales_item&); friend std::ostream& operator<<(std::ostream&, const Sales_item&); friend bool operator<(const Sales_item&, const Sales_item&); friend bool operator==(const Sales_item&, const Sales_item&); public: // constructors are explained in section 7.1.4, pages 262 - 265 // default constructor needed to initialize members of built-in type #if defined(IN_CLASS_INITS) && defined(DEFAULT_FCNS) Sales_item() = default; #else Sales_item(): units_sold(0), revenue(0.0) { } #endif Sales_item(const std::string &book): bookNo(book), units_sold(0), revenue(0.0) { } Sales_item(std::istream &is) { is >> *this; } public: // operations on Sales_item objects // member binary operator: left-hand operand bound to implicit this pointer Sales_item& operator+=(const Sales_item&); // operations on Sales_item objects std::string isbn() const { return bookNo; } double avg_price() const; // private members as before private: std::string bookNo; // implicitly initialized to the empty string #ifdef IN_CLASS_INITS unsigned units_sold = 0; // explicitly initialized double revenue = 0.0; #else unsigned units_sold; double revenue; #endif }; // used in chapter 10 inline bool compareIsbn(const Sales_item &lhs, const Sales_item &rhs) { return lhs.isbn() == rhs.isbn(); } // nonmember binary operator: must declare a parameter for each operand Sales_item operator+(const Sales_item&, const Sales_item&); inline bool operator==(const Sales_item &lhs, const Sales_item &rhs) { // must be made a friend of Sales_item return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue && lhs.isbn() == rhs.isbn(); } inline bool operator!=(const Sales_item &lhs, const Sales_item &rhs) { return !(lhs == rhs); // != defined in terms of operator== } // assumes that both objects refer to the same ISBN Sales_item& Sales_item::operator+=(const Sales_item& rhs) { units_sold += rhs.units_sold; revenue += rhs.revenue; return *this; } // assumes that both objects refer to the same ISBN Sales_item operator+(const Sales_item& lhs, const Sales_item& rhs) { Sales_item ret(lhs); // copy (|lhs|) into a local object that we'll return ret += rhs; // add in the contents of (|rhs|) return ret; // return (|ret|) by value } std::istream& operator>>(std::istream& in, Sales_item& s) { double price; in >> s.bookNo >> s.units_sold >> price; // check that the inputs succeeded if (in) s.revenue = s.units_sold * price; else s = Sales_item(); // input failed: reset object to default state return in; } std::ostream& operator<<(std::ostream& out, const Sales_item& s) { out << s.isbn() << " " << s.units_sold << " " << s.revenue << " " << s.avg_price(); return out; } double Sales_item::avg_price() const { if (units_sold) return revenue/units_sold; else return 0; } #endif
相关文章推荐
- <C++ Primer_5th>习题_3.5
- <C++ Primer_5th>习题_3.17
- <C++ Primer_5th>习题_3.6
- <C++ Primer_5th>习题_3.14
- <C++ Primer_5th>习题_1.3
- C++ Primer 第5版 第一章书店程序Sales_item问题
- <C++ Primer_5th>习题_3.25
- <C++ Primer_5th>习题_1.22
- <C++ Primer_5th>习题_3.2
- C++ Primer 第五版第一章Sales_item.h源码
- <C++ Primer_5th>习题_3.3
- 我刚刚写了一个map的题目,还用到了#include<string>的头文件,下面我来总结一下 map<类型>变量 q q.find(找字符串) q.end()是否到达末尾
- 关于C++头文件#include<iostream.h>debug时提示文件目录不存在错误解决方法?
- android背景设置报错 <item> tag requires a 'drawable' attribute or child tag defining a drawable<转>
- 预处理文件,包含预订头文件<>和””有什么区别?
- IEnumerator<TItem>和IEnumerator Java 抽象类和普通类、接口的区别——看完你就顿悟了
- C++中头文件<iostream>介绍
- [C++STDlib基础]关于日期时间的操作——C++标准库头文件<ctime>
- [C++STDlib基础]关于数学函数的介绍——C++标准库头文件<cmath>
- 关于<TabNavigator>的item的一些用法 例如传递navigation