Sales_item.h

下列是《C++primer》书中介绍和使用的Sales_item.h类

经测试可以使用，现在贴在这里，分享给大家！

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版本一：

#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;
    else
    s = 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;
    else
    return 0;
}
#endif

1. #ifndef SALESITEM_H  
2. #define SALESITEM_H  
3. #include <iostream>  
4. #include <string>  
5.    
6.    
7. class Sales_item  
8. {  
9. public:  
10.     Sales_item(const std::string &book):isbn(book),units_sold(0),revenue(0.0){}  
11.     Sales_item(std::istream &is){ is >> *this;}  
12.     friend std::istream& operator>>(std::istream &,Sales_item &);  
13.     friend std::ostream& operator<<(std::ostream &,const Sales_item &);  
14. public:  
15.     Sales_item & operator+=(const Sales_item&);  
16. public:  
17.     double avg_price() const;  
18. bool same_isbn(const Sales_item &rhs)const  
19. {  
20.     return isbn == rhs.isbn;  
21. }  
22. Sales_item():units_sold(0),revenue(0.0){}  
23. public:  
24.     std::string isbn;  
25.     unsigned units_sold;  
26.     double revenue;  
27. };  
28.    
29. using std::istream;  
30. using std::ostream;  
31. Sales_item operator+(const Sales_item &,const Sales_item &);  
32. inline bool operator==(const Sales_item &lhs,const Sales_item &rhs)  
33. {  
34.     return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue && lhs.same_isbn(rhs);  
35. }  
36. inline bool operator!=(const Sales_item &lhs,const Sales_item &rhs)  
37. {  
38.     return !(lhs == rhs);  
39. }  
40.    
41. inline Sales_item & Sales_item::operator +=(const Sales_item &rhs)  
42. {  
43.     units_sold += rhs.units_sold;  
44.     revenue += rhs.revenue;  
45.     return *this;  
46. }  
47. inline Sales_item operator+(const Sales_item &lhs,const Sales_item &rhs)  
48. {  
49.     Sales_item ret(lhs);  
50.     ret += rhs;  
51.     return ret;  
52. }  
53. inline istream& operator>>(istream &in,Sales_item &s)  
54. {  
55.     double price;  
56.     in >> s.isbn >> s.units_sold >> price;  
57.     if(in)  
58.          s.revenue = s.units_sold * price;  
59.     else  
60.     s = Sales_item();  
61.     return in;  
62. }  
63. inline ostream& operator<<(ostream &out,const Sales_item &s)  
64. {  
65.     out << s.isbn << "t" <<s.units_sold << "t" << s.revenue << "t" << s.avg_price();  
66.     return out;  
67. }  
68. inline double Sales_item::avg_price() const  
69. {  
70.     if(units_sold)  
71.         return revenue/units_sold;  
72.     else  
73.     return 0;  
74. }  
75. #endif  

版本二：

#ifndef SALES_ITEM_H_
#define SALES_ITEM_H_

#include <iostream>
#include <String>

/// Start class
class Sales_item
{
public:
	Sales_item():units_sold(0),revenue(0.0){}
	Sales_item(const std::string &book):isbn(book),units_sold(0),revenue(0.0){}
	Sales_item(std::istream & in){in >> *this;}
	virtual ~Sales_item(){}
	double avg_price() const;
        bool same_isbn(const Sales_item &)const;
	
	Sales_item & operator+=(const Sales_item &);
	friend std::istream & operator>>(std::istream &,Sales_item &);
	friend std::ostream & operator<<(std::ostream &,const Sales_item &);

	// 二元运算符重载的成员函数只能有一个参数，所以不能放此处

	// Sales_item operator+(const Sales_item &,const Sales_item &);
	// bool operator==(const Sales_item &,const Sales_item &);
	// bool operator!=(const Sales_item &,const Sales_item &);	

	std::string isbn;
	unsigned units_sold;
	double revenue;
};
/// End class

	Sales_item operator+(const Sales_item &,const Sales_item &);

/// Class function
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 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 std::istream & operator>>(std::istream &in,Sales_item &s)
{
	double price;
	in >> s.isbn >> s.units_sold >>price;
	if(in)
		s.revenue = s.units_sold * price;
	else
	s = Sales_item();
	return in;
}
inline std::ostream & operator<<(std::ostream &out,const Sales_item &s)
{
	out << s.isbn << " " << s.units_sold << " " << s.revenue << " " << s.avg_price();
	return out;
}
inline double Sales_item::avg_price() const
{
	if(units_sold)
		return revenue/units_sold;
	else
		return 0;
}
inline bool Sales_item::same_isbn(const Sales_item &rhs)const
{
	return isbn == rhs.isbn;
}
/// End class function
#endif