大神帮忙看一下这个问题怎么解决
Linking...
FtpClient.obj : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CFtpClientDoc::classCFtpClientDoc" (?classCFtpClientDoc@CFtpClientDoc@@2UCRuntimeClass@@B)
FtpClient.obj : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CMainFrame::classCMainFrame" (?classCMainFrame@CMainFrame@@2UCRuntimeClass@@B)
FtpClient.obj : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CFtpClientView::classCFtpClientView" (?classCFtpClientView@CFtpClientView@@2UCRuntimeClass@@B)
Debug/FtpClient.exe : fatal error LNK1120: 3 unresolved externals
执行 link.exe 时出错.
FtpClient.exe - 1 error(s), 0 warning(s)