《C++ primer 4th》习题 7-31 记录

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// Sales_iterm.h#ifndef SALES_ITERM_H_INCLUDED#define SALES_ITERM_H_INCLUDED#include <iostream>#include <string>//using std::string;//using std::istream;//using std::ostream;class Sales_iterm{public:  std::istream& input(std::istream &in);  std::ostream& output(std::ostream &out) const;  double avg_price() const;// 1、**************************************************  bool same_isbn(const Sales_iterm &rhs) const  {    return isbn == rhs.isbn;  }  Sales_iterm(): unit_sold(0), revenue(0.0) {}private:  std::string isbn;  unsigned unit_sold;  double revenue;};#endif // MYSALES_ITERM_H_INCLUDED

//Sales_iterm.cpp#include "Sales_iterm.h"std::istream& Sales_iterm::input(std::istream &in){  in >> isbn >> unit_sold >> revenue;  return in;}std::ostream& Sales_iterm::output(std::ostream &out) const{  out << "ISBN: " << isbn << std::endl << "units sold: "      << unit_sold << std::endl << "revenue: " << revenue << std::endl;  return out;}double Sales_iterm::avg_price() const{  if (unit_sold)  {    return revenue/unit_sold;  }  return 0;}

// main.cpp#include <iostream>#include "Sales_iterm.cpp"using namespace std;int main(){  Sales_iterm salesiterm1, salesiterm2;  salesiterm1.input(cin);  salesiterm2.input(cin);  if (salesiterm1.same_isbn(salesiterm2))  {    cout << "X" << endl;  }//  saleiterm.output(cout);//  cout << saleiterm.avg_price();  return 0;}

1、Sales_iterm 类将数据成员isbn定义为private，这并不意味着rhs.isbn是错误的。
2、涉及到多文件的编译两种方法：a. 创建一个工程 b. 包含相应的文件

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