error LNK2005的解决_error lnk2005 std::basic-优快云博客

本文链接：https://blog.youkuaiyun.com/pang040328/article/details/4328270

本文介绍了一种常见的编译错误LNK2005，该错误通常出现在C++项目中，当同一函数在多个.obj文件中被定义时发生。文章详细解释了一个特定的例子，并给出了正确的解决方案：将重载的输入流操作符从头文件移至.cpp文件。

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Bid.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>buildbidpage.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>Bid.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>buildbidpage.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>Categories.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>Category.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>Listing.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>main.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>processrequest.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>bidhistory.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>buildpage.obj : error LNK2005: "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class Bid &)" (??5@YAAAV?$basic_istream@DU?$char_traits@D@std@@@std@@AAV01@AAVBid@@@Z) 已经在 Advertisement.obj 中定义 1>./Debug/main.exe : fatal error LNK1169: 找到一个或多个多重定义的符号

网上说了各种解决方案，都不适合自己的情况，仔细检查之后，发觉造成这个错误的原因是 istream &operator>>(istream &stream, Bid &b){ string email; float amount; int quantity; Date date; stream>>email>>amount>>quantity>>date; b.setEmail(email); b.setAmount(amount); b.setQuantity(quantity); b.setDate(date); return stream; };

上面这个函数的声明了定义写在了Bid.h这个头文件中，而其它的函数的定义是写在.cpp文件中，把这个操作符重载的方法体写在.cpp文件即可。