一个奇怪的错误错误 4 error LNK1120: 3 个无法解析的外部命令G:\visual studio2010\visual studio 2010

[feidegengao]

错误 1 error LNK2019: 无法解析的外部符号 "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Sales_item const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABVSales_item@@@Z)，该符号在函数 _main 中被引用 G:\visual studio2010\visual studio 2010 编程实例\lianxi2\lianxi2\sales_item.obj lianxi2
错误 2 error LNK2019: 无法解析的外部符号 "class Sales_item __cdecl operator+(class Sales_item const &,class Sales_item const &)" (??H@YA?AVSales_item@@ABV0@0@Z)，该符号在函数 _main 中被引用 G:\visual studio2010\visual studio 2010 编程实例\lianxi2\lianxi2\sales_item.obj lianxi2
错误 3 error LNK2019: 无法解析的外部符号 "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Sales_item &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVSales_item@@@Z)，该符号在函数 _main 中被引用 G:\visual studio2010\visual studio 2010 编程实例\lianxi2\lianxi2\sales_item.obj lianxi2

#include "Sales_item.h"
#include <iostream>
#include <string>
using namespace std;
inline
	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
}
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 isbn
inline
	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


inline
	istream& 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;
}

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;
}

感觉莫名其妙呀，代码都没写错呀！谢谢大家了

[heartlesstoanyone]

你上面的代码没有被编进去。

[赵4老师]

重建所有

[酱油党]

rebuilt

[酱油党]

可能是你启用了最小化编译的原因，清除后重新编译

[elina_helingyue]

我也重建了，也清除后重新编译了，都不行啊