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第一章 快速入门
C++ Primer 中文版，第4版
/*
第一章 快速入门
第二章 变量和基本类型
第三章 标准库类型
第四章 数组和指针
第五章 表达式
第六章 语句
第七章 函数
第八章 标准IO库
第九章 顺序容器
第十章 关联容器
第11章 泛型算法
第12章 类
第13章 复制控制
第14章 重载操作符与转换
第15章 面向对象编程
第16章 模板和泛型编程
第17章 用于大型程序的工具
第18章 特殊工具与技术
*/
/*
第一章 快速入门
第一部分：基本语言-------------------------------------------
第二章 变量和基本类型
第三章 标准库类型
第四章 数组和指针
第五章 表达式
第六章 语句
第七章 函数
第八章 标准IO库
第二部分：容器和算法----------------------------------------
第九章 顺序容器
第十章 关联容器
第11章 泛型算法
第三部分：类和数据抽象--------------------------------------
第12章 类
第13章 复制控制
第14章 重载操作符与转换
第四部分：面向对象编程与泛型编程--------------------------
第15章 面向对象编程
第16章 模板和泛型编程
第五部分：高级主题------------------------------------------
第17章 用于大型程序的工具
第18章 特殊工具与技术
*/
第一章 快速入门
// Sales_item.h
/* * This file contains code from "C++ Primer, Fourth Edition", by Stanley B. * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the * copyright and warranty notices given in that book: * * "Copyright (c) 2005 by Objectwrite, Inc., Jose 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 Contracts Department * 75 Arlington Street, Suite 300 * Boston, MA 02216 * Fax: (617) 848-7047*/ #ifndef SALESITEM_H#define SALESITEM_H// Definition of Sales_item class and related functions goes here#include <iostream>#include <string>class Sales_item {friend bool operator==(const Sales_item&, const Sales_item&);// other members as beforepublic: // added constructors to initialize from a string or an istream 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: // operations on Sales_item objects // member binary operator: left-hand operand bound to implicit this pointer Sales_item& operator+=(const Sales_item&); // other members as before public: // operations on Sales_item objects double avg_price() const; bool same_isbn(const Sales_item &rhs) const { return isbn == rhs.isbn; } // default constructor needed to initialize members of built-in type Sales_item(): units_sold(0), revenue(0.0) { }// private members as beforeprivate: std::string isbn; unsigned units_sold; double revenue;};// nonmember binary operator: must declare a parameter for each operandSales_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.same_isbn(rhs);}inline bool operator!=(const Sales_item &lhs, const Sales_item &rhs){ return !(lhs == rhs); // != defined in terms of operator==}using std::istream; using std::ostream;// assumes that both objects refer to the same isbninlineSales_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 isbninlineSales_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}inlineistream& operator>>(istream& in, Sales_item& s){ double price; in >> s.isbn >> 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;}inlineostream& operator<<(ostream& out, const Sales_item& s){ out << s.isbn << "\t" << s.units_sold << "\t" << s.revenue << "\t" << s.avg_price(); return out;}inlinedouble Sales_item::avg_price() const{ if (units_sold) return revenue/units_sold; else return 0;}#endif
Code:
// 1、编写简单的C++程序 ------------------------------------------------int main(){ return 0;}// 2、初窥输入/输出 ---------------------------------------------------#include <iostream>int main(){ std::cout << "Enter two numbers:" << std::endl; int v1, v2; std::cin >> v1 >> v2; std::cout << "The sum of " << v1 << " and " << v2 << " is " << v1 + v2 << std::endl; return 0;}// 3、关于注释 --------------------------------------------------------------/* Simple main function: Read two numbers and write their sum */#include <iostream>int main(){ // prompt user to enter two numbers std::cout << "Enter two numbers:" << std::endl; int v1, v2; //uninitialized std::cin >> v1 >> v2; // read input return 0;}// 4、控制结构 -------------------------------------------------------------// while#include <iostream>int main(){ int sum = 0, val = 1; // keep executing the while until val is greater than 10 while(val <= 10) { sum += val; // assigns sum + val to sum ++val; // add 1 to val } std::cout << "Sum of 1 to 10 inclusive is " << sum << std::endl; return 0;}// for#include <iostream>int main(){ int sum = 0; // sum values from 1 up to 10 inclusive for(int val = 1; val <= 10; ++val) sum += val; // equivalent to sum = sum + val std::cout << "Sum of 1 to 10 inclusive is " << sum << std::endl; return 0;}// if#include <iostream>int main(){ std::cout << "Enter two numbers:" << std::endl; int v1, v2; std::cin >> v1 >> v2; // read input // use smaller number as lower bound for summation // and larger number as upper bound int lower, upper; if(v1 <= v2) { lower = v1; upper = v2; } else { lower = v2; upper = v1; } int sum = 0; // sum values from lower up to and including upper for(int val = lower; val <= upper; ++val) sum += val; // sum = sum + val std::cout << "Sum of " << lower << " to " << upper << " inclusive is " << sum << std::endl; return 0;}// end of file. Ctrl+z 可以模拟文件尾#include <iostream>int main(){ int sum = 0, value; // read till end-of-file, calculating a running total of all values read while(std::cin >> value) sum += value; // equivalent to sum = sum + value std::cout << "Sum is: " << sum << std::endl; return 0;}// 5、类的简介 ----------------------------------------------------/*必须将Sales_item.h文件，放在程序文件的同一目录下，这个程序才可以运行。Sales_item.h文件，目前不要求读者制作。Sales_item.h文件具体内容，在最前面。*/#include <iostream>#include "Sales_item.h"int main(){ Sales_item book; // read ISBN, number of copies sold, and sales price std::cin >> book; // write ISBN, number of copies sold, total revenue, and average price std::cout << book << std::endl; return 0;}// input: 0-201-70353-X 4 24.99// 对象之和#include <iostream>#include "Sales_item.h"int main(){ Sales_item item1, item2; std::cin >> item1 >> item2; // read a pair of transactions std::cout << item1 + item2 << std::endl; // print their sum return 0;}/*0-201-78345-X 3 20.000-201-78345-X 2 25.00*/// 成员函数#include <iostream>#include "Sales_item.h"int main(){ Sales_item item1, item2; std::cin >> item1 >> item2; // first check that item1 and item2 represent the same book if(item1.same_isbn(item2)) { std::cout << item1 + item2 << std::endl; return 0; // indicate success } else { std::cerr << "Data must refer to same ISBN" << std::endl; return - 1; // indicate failure }}/*0-201-78345-X 3 20.000-201-78345-X 2 25.000-201-78345-X 3 20.000-888-78345-X 2 25.00*/// 6、C++程序 ------------------------------------------------------#include <iostream>#include "Sales_item.h"int main(){ // declare variables to hold running sum and data for the next record Sales_item total, trans; // is there data to process? if(std::cin >> total) { // if so, read the transaction records while(std::cin >> trans) if(total.same_isbn(trans)) // match: update the running total total = total + trans; else { // no match: print & assign to total std::cout << total << std::endl; total = trans; } // remember to print last record std::cout << total << std::endl; } else { // no input!, warn the user std::cout << "No data?!" << std::endl; return - 1; // indicate failure } return 0;}
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第一章 快速入门
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