error LNK2019: unresolved external symbol "__declspec(dllimport) const CReadUserInfo::`vftable'" (__

使用VS2010编写DLL工程时出现如下错误 
Creating library E:\Product1\DlagDll\Debug\DlagDll.lib and object E:\Product1\DlagDll\Debug\DlagDll.exp 
1>ReadUserInfo.obj : error LNK2019: unresolved external symbol “_declspec(dllimport) const CReadUserInfo::`vftable’” (__imp[email protected]@[email protected]) referenced in function “public: __thiscall CReadUserInfo::CReadUserInfo(void)” ([email protected]@[email protected]) 
1>E:\Product1\DlagDll\Debug\DlagDll.dll : fatal error LNK1120: 1 unresolved externals

在VS2010工程的project->setting->C/C++->Preprocessor definitions中添加宏定义即可