Re: C++ using COM

From:

Ulrich Eckhardt <eckhardt@satorlaser.com>

Newsgroups:

microsoft.public.vc.language

Date:

Mon, 11 Dec 2006 13:38:58 +0100

Message-ID:

<940054-ims.ln1@satorlaser.homedns.org>

Aidal wrote:

BOOL APIENTRY DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID
lpReserved)
{
  CoInitialize(NULL);

  HRESULT hRes = pFtpCmdParser.CreateInstance(
                     MyInterop::CLSID_FtpCmdParser);

  switch (ul_reason_for_call)
  {
  case DLL_THREAD_ATTACH:
  case DLL_THREAD_DETACH:
    return 1;

  case DLL_PROCESS_ATTACH:
    buffer = (char*)malloc(STRMAX* sizeof(char));
    if(buffer == NULL)
    {
      CoUninitialize ();
      return 0;
    }
    else
    {
      return 1;
    }

  case DLL_PROCESS_DETACH:
    free(buffer);
    return 0;
  }

CoUninitialize ();
return 0;
}

Look up the documentation for DllMain() in the MSDN[1]. You will see when
this is called. Then, imagine the case of your program, step through the
function and look at what it does. You will notice:
- some parts will never be called
- some parts that should only be called once are called multiple times

Further, what is 'buffer'? Why isn't it just a static array, because that's
what it is used as! Also, why the strange size of 255 characters? Oh, and
BTW, the size of a C++ 'char' is by definition 1, no need for it in the
call to malloc(). Lastly, DllMain returns a BOOL, and while this is
technically no difference, it would be better if you used TRUE and FALSE
instead of 1 and 0 as returnvalues.

Uli

[1] msdn.microsoft.com