友元和重载的问题

[jhldelphi]

#include "stdafx.h"
//#include "..\..\comm\Sales_item.h"

#include <iostream>
#include <string>
using namespace std;

class Sales_item
{
	friend istream& operator>>(istream &in, Sales_item &s);
public:
	Sales_item(): units_sold(0), revenue(0.0) {}
	Sales_item(const string &book):isbn(book), units_sold(0), revenue(0.0){}
	
public:
	Sales_item& operator+=(const Sales_item &);
  
public:
	double avg_price() const;
	inline bool same_isbn(const Sales_item &rhs) const { return isbn == rhs.isbn;}

private:
	string isbn;
	unsigned units_sold;
	double revenue;
};

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 Sales_item& Sales_item::operator+=(const Sales_item &rhs)
{
	units_sold += rhs.units_sold;
	revenue += rhs.revenue;
	return *this;
}

inline double Sales_item::avg_price() const
{
	if(units_sold)
	{
		return revenue / units_sold;
	}
	else
	{
		return 0;
	}
}

int main(int argc, char* argv[])
{

	Sales_item book;
	
	/*
	cout << "Enter transactions: " << endl;
	while(cin >> book)
	{
		cout << "ISBN, number of copies sold, "
			 << "total revenue, and average price are: "
			 << endl;
		cout << book << endl;
	}
	*/
	return 0;
}

error C2248: 'isbn' : cannot access private member declared in class 'Sales_item'
error C2248: 'units_sold' : cannot access private member declared in class 'Sales_item'
error C2248: 'revenue' : cannot access private member declared in class 'Sales_item'

[就想叫yoko]

我VC05没问题呀

[KID_coder]

vs2010可以通过~

[KID_coder]

cout << book << endl;
没有重载<<

[bdmh]

未注释的代码可以正常编译，注释代码中
cout << book << endl;这里没有对book的类，实现<<的重载

[jhldelphi]

[Quote=引用 4 楼 bdmh 的回复:]
未注释的代码可以正常编译，注释代码中
cout << book << endl;这里没有对book的类，实现<<的重载
[/Quote]

输出的我删掉了，没加上去

[jhldelphi]

我在VC6下面，编译通不过。报上面的错误。

[Louistao]

elipse+ MinGw下也没问题

[jhldelphi]

再等等

[飞天御剑流]

这是VC6的问题，那个>>友元重载的定义要放到类体中。

VC6有太多不符合标准的地方，远离VC6！

[gergerman]

的确啊，vc6对c++兼容不全面
换个vc2008吧~用着感觉不错，加多个visual X插件就更好