Re: Can't compile VC++ program that call a VB DLL

From:

"David Ching" <dc@remove-this.dcsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 4 Feb 2009 17:38:55 -0800

Message-ID:

<61A2FFB1-68C5-44BB-A1E9-833D52ACC2B7@microsoft.com>

"Tim Slattery" <Slattery_T@bls.gov> wrote in message
news:o8pjo4dpqaq9hgignpefoamcfd7kch6huk@4ax.com...

Now I'm getting unresolved externals. In the dgsCrypto_i.cpp file that
I made by compiling the *.idl file is this:

const IID IID__dgsAES =
{0xBC82FBAC,0x9F60,0x418D,{0xA4,0xE6,0x24,0xF0,0x32,0x51,0x1F,0xFB}};

const CLSID CLSID_dgsAES =
{0xEA20384E,0x4D4B,0x46CC,{0xAC,0x2D,0x51,0x4D,0x4F,0xDF,0xF9,0xC8}};

My CoCreateInstance call is as follows:

   _dgsAES *IVBdgsAES = NULL;

   hr = CoCreateInstance( CLSID_dgsAES,
       NULL,
       CLSCTX_INPROC_SERVER,
       IID__dgsAES,
       (void**) &IVBdgsAES);

I get these error messages:

xxvbdll.obj : error LNK2001: unresolved external symbol _CLSID_dgsAES
xxvbdll.obj : error LNK2001: unresolved external symbol _IID__dgsAES

What have I missed now?

The details are fuzzy, but you need to

#define INIT_GUID

before including the header file that declares IID__dgsAES in exactly *one*
of your files so that the variable is declared. But only one file, or else
you will get multiply defined symbols.

-- David