Referencing GUIDs - winapi

Question

I'm trying to capture an event and reference a GUID to see which event it is. The code is below:
DWORD WINAPI AvisionEventProc(LPVOID lpParam){
//HANDLE hEvent = * (HANDLE *) lpParam; // This thread's read event
STINOTIFY pStiNotify;
if (debug){
wprintf(L"Avision Event\n");
}
while(true){
WaitForSingleObject(hAvisionEvent, INFINITE);
wprintf(L"Event");
pStiDevice->GetLastNotificationData(&pStiNotify);
if (pStiNotify.guidNotificationCode == GUID_STIUserDefined1){
wprintf(L"User defined 1");
}else if (pStiNotify.guidNotificationCode == GUID_STIUserDefined2){
wprintf(L"User defined 2");
}else if (pStiNotify.guidNotificationCode == GUID_STIUserDefined3){
wprintf(L"User defined 3");
}
ResetEvent(hAvisionEvent);
}
return 1;
}
This compiles just fine but I get the errors below when linking:
1>sti.obj : error LNK2001: unresolved external symbol _GUID_STIUserDefined3
1>sti.obj : error LNK2001: unresolved external symbol _GUID_STIUserDefined2
1>sti.obj : error LNK2001: unresolved external symbol _GUID_STIUserDefined1
The strange thing is that sti.h is linked in as I am pulling other constants from it. I did notice by the GUID decleration the following:
#if defined( _WIN32 ) && !defined( _NO_COM)
/*
* Class IID's
*/
// B323F8E0-2E68-11D0-90EA-00AA0060F86C
DEFINE_GUID(CLSID_Sti, 0xB323F8E0L, 0x2E68, 0x11D0, 0x90, 0xEA, 0x00, 0xAA, 0x00, 0x60, 0xF8, 0x6C);
/*
* Interface IID's
*/
// {641BD880-2DC8-11D0-90EA-00AA0060F86C}
DEFINE_GUID(IID_IStillImageW, 0x641BD880L, 0x2DC8, 0x11D0, 0x90, 0xEA, 0x00, 0xAA, 0x00, 0x60, 0xF8, 0x6C);
<snip>
/*
* Standard event GUIDs
*/
// {740D9EE6-70F1-11d1-AD10-00A02438AD48}
DEFINE_GUID(GUID_DeviceArrivedLaunch, 0x740d9ee6, 0x70f1, 0x11d1, 0xad, 0x10, 0x0, 0xa0, 0x24, 0x38, 0xad, 0x48);
<snip>
#endif
Does the "if defined" line stop the GUIDs being referenced (I am writing a win32 console app) or is there something more fundamental I have wrong here to do with a lack of understanding on GUIDs?
Thanks, in advance for your help.
Cheers,
Neil

Answer 1

#include <initguid.h>should be added. That will help.

Answer 2

The DEFINE_GUID macro either defines a named GUID as a static, or just does a forward declaration to actually be done somewhere else, depending on if #include <initguid.h> has been previously declared. Your code perhaps only have the latter, and the symbols don't have actual initialization within the project.
See:
How to avoid error "LNK2001 unresolved external" by using DEFINE_GUID
INITGUID: An Explanation
How does the DEFINE_GUID macro work? - at the bottom of the page