Createdispatch problem (PLEASE help) 1

[howardnl]

Hello everyone,

Here is my problem. I created an exe that was basically a collection of functions and it worked fine. It created an Excel spreadsheet, put some data in cells, and saved it. It uses Createdispatch to open Excel. I wanted to move these functions to a dll, but when I call Createdispatch in the dll it doesn't work. Any help at all is greatly appreciated.

Thanks,
Nick

 

[MSamoila]

The most common problem is that you didn't initiate the COM apartment by calling

CoInitialize(NULL)

.

The DLL works into the COM apartment of the EXE file.

Test this: run the Debug version of DLL form Visual Studio environment in order to catch all TRACE messages. If

CoCreateInstance()

function fails inside

CreateDispatch()

function (a good idea is to run step by step the CreateDispatch's code) then the return code of

CoCreateInstance()

function will describe the error. The error will be dumped into debug window. I guess you will see the

CO_E_NOTINITIALIZED

error code (0x800401F0L).

Resolution: Add

CoInitialize(NULL)

/

CoUninitialize()

in your start up /end code of the EXE file which loads the DLL (

InitInstance()

/

ExitInstance()

functions).

Tip: Instead using old Dispatch wrapper classes you should use

#import

directive which works faster without Invoke.

Marius Samoila
Brainbench MVP for Visual C++

http://www.brainbench.com

 

[howardnl]

Thank you very much for your help. You are absolutely correct and now it works as it should. I'm kind of new to this type of stuff, so what is the #import directive and how is it used? If you know of a site with a good explannation that would be great. Any additional help is greatly appreciated. Thanks again.