COM Client in C

Question

I have some C++ sample client code which uses COM objects
Below is the code flow in C++.
1)Creates an instance of base INIT class(INIT is a class/interface)
2)passes the IUnknown to QueryInterface function and gets the interface pointer of the specific event
(the returned interface pointer will be inherited of the required event type)
3) registers the events.....
I got a requirement to implement the same in C , used the activex Controller template and generated the .c file , .h file and fp file
for the registered active X server
Step 1) NewIINIT class function and will get the CAObjHandle for the INIT interface(class)
after this step i am befuddled about how to go !
Please anyone help me out ASAP.
Can the above process be implemented in CVI ..is it feasible
Thanks in advance
Satish

Answer 1

Hi
I'll send you an example of how I retreve a 2D array from an ActiveX control
in C++ an how it is wired in LV
Hans
wrote in message news:892sjt$c0i$[email protected]..
> Hi!
>
> I have constructed a com-object in visual c++. This object will just
> return an array of variants. The method connected to the interface has
> one out parameter that consists of a pointer to a variant. I dont know
> how labview handles this type. It seems that it doesnt recognize the
> type. It just gives the error message, "A null reference pointer was
> passed through the stub"?!?! I have also written a com-client in c++
> that communicates with this com-server. This one works fine! How does
> labview handles arrays?! I have also tried to just return one "Var
iant
> value" from the server. Same problem here, "A null....".#"¤%"%
>
> com-server implementation:
>
> STDMETHODIMP CTEEServices::TestVariant7(VARIANT inData, VARIANT
> *pOutData)
> {
> VariantInit(pOutData);
> LPVOID pvdata;
> int *pElement;
>
> pOutData->vt=VT_ARRAY;//Set VARIANT type to array
> SAFEARRAYBOUND rgsabound[1];
> rgsabound[0].lLbound=0;
> rgsabound[0].cElements=10;//10 elements
> pOutData->parray=SafeArrayCreate(VT_I4,1,rgsabound); file://Create a
> safearray in VARIANT
> pvdata=pOutData->parray->pvData; file://Get address to array
> pElement=(int*)pvdata;
>
> for(int i=0;i<10;i++) file://Fill it up!
> {
> *pElement=i;
> pElement+=1;
> }
>
> return S_OK;
> }
>
> regards,
> Peter
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
[Attachment C2 test.vi, see below]
[Attachment ActiveX.txt, see below]
Attachments:
C2_test.vi ‏29 KB
ActiveX.txt ‏1 KB