How can I avoid this error: nafxcwd.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in MyThing.obj
This happens when you have a DllMain in a DLL that uses MFC.
MFC has its own DllMain (in nafxcwd.lib).
If you are going to use MFC you can't have a DllMain.
If you simply want to get the instance handle you can use
hHandle = AfxGetInstanceHandle();
in your DLL.
To do more you need to define your own class based on CWinApp
and do initialization in InitInstance();
class CMyClass : public CWinApp
virtual BOOL InitInstance();