Passing a variant of type VT_INT as a function argument

[onlyshiza]

Hi everyone,

I am calling a method in a COM dll that as the first parameter takes a VARIANT of type VT_INT (actually it has to be like a VARIANT array of (1,0,0), see the following code for more clarification). I am trying to make it work in C++. I have the equivalent working VB code which is likein the following code pM is the pointer to an interface)

dim XVect
XVect = pM.RotateVector(Array(1, 0, 0))

and it works perfect, i.e the Array function in VB does the trick.

Now in C++, I am trying this:

_variant_t var;
VariantInit(&var);
var.vt = VT_ARRAY | VT_INT;
var.parray= (1,0,0);
//pM is a smart pointer to an interface
pM->RotateVector(&var);

But I am getting an Unknown error on the last line (I have tried it with VARIANT instead of _variant_t as well). Any ideas of what I am doing wrong here? I thought maybe I have to first put my array of (1,0,0) in a safeArray and then assign the safearray to var.parray before passing var to the function. Am I way off?
Appreciate any comments.

onlyshiza

 

[LazyMe]

I'm not sure how to use the variant_t, because I always use plain VARIANTS. In the VARIANT way of programming you need to create a SAFEARRAY and set the parray value of the VARIANT to the pointer returned by SafeArrayCreate().

So my guess is that you're not that far off....

Greetings,
Rick

 

[onlyshiza]

thanks for your reply Rick,

Now I am using the VARIANT and setting the value of it from a SAFEARRAY like this:

int tempArray[3]={1,0,0};	
VARIANT var;
VariantInit(&var);
var.vt = VT_ARRAY | VT_INT;
SAFEARRAY* pSafArr;
SAFEARRAYBOUND safArrBnds = {3, 0};
pSafArr = SafeArrayCreate(VT_INT, 1, &safArrBnds);   
int* inputArray= new int[3];		
SafeArrayAccessData(pSafArr, reinterpret_cast<void**>(&inputArray));
for(int i = 0; i < 3; i++)
  inputArray[i] = tempArray[i];
SafeArrayUnaccessData(pSafArr);
var.parray = pSafArr;
//The following line throws an unknown error-
//pM is a smart pointer to an interface
pM->RotateVector(&var);

The interesting thing is if I extract the values stored in var before calling the RotateVector method, the values comeup correctly (1,0,0), so the SAFEARRAY and var are doing their job. I am sure the smart pointer to the interface (pM) is valid as I am calling other methods from it.

this is the prototype of the RotateVector in VB (which as I mentioned before is working perfectly in VB)

Public Function RotateVector(ByVal InVector As Variant) As Variant

Any ideas what may be wrong?

Thanks,