error LNK2001: unresolved external symbol "public: virtual enum TCPSError

error LNK2001: unresolved external symbol "public: virtual enum TCPSError
__thiscall CSqliteOperation::ReadDeviceGroup(struct
mcu_meu_interface_TypesBase::DeviceGroupSearchCon const &,struct
tcps_Array<struct mcu_meu_interface_TypesBase::DeviceGroupInfo> &)"
(?ReadDeviceGroup@CSqliteOperation@@UAE?AW4TCPSError@@ABUDeviceGroupSearchCon@mcu_meu_interface_TypesBase@@AAU?$tcps_Array@UDeviceGroupInfo@mcu_meu_interface_TypesBase@@@@@Z)

如上测错误，

是因为在cpp文件中 类的函数名称之前没有加 类名：：

即  A.h

class A

{

int bb();

}

A.cpp 文件中

直接写 int bb(() 

{ return 1;}

当然不行，应该写 int A::bb() {...}