Re: VB function called from c++
"Jake" wrote:
This is my code
int u_dll_imstest_call(wchar_t *TheConnectString, wchar_t
*TheTable,
wchar_t *TheFields, wchar_t *ThePopupTitle, wchar_t
*TheOrderBy,
wchar_t *TheWhereClause, wchar_t *ThePosition)
{
// Declare an HRESULT and a pointer to the clsCat16
interface
HRESULT hr;
_bstr_t bTheConnectString(TheConnectString);
//TheConnectString
creates a _bstr_t wrapper
_bstr_t bTheTable(TheTable); //TheTable creates a _bstr_t
wrapper
_bstr_t bTheFields(TheFields); //TheFields creates a
_bstr_t wrapper
_bstr_t bThePopupTitle(ThePopupTitle); // ThePopupTitle
creates a
_bstr_t wrapper
_bstr_t bTheOrderBy(TheOrderBy); //TheOrderBy creates a
_bstr_t
wrapper
_bstr_t bTheWhereClause(TheWhereClause); //TheWhereClause
creates a
_bstr_t wrapper
_bstr_t bThePosition(ThePosition); //ThePosition creates a
_bstr_t
wrapper
_bstr_t bvalue;
_clsCat16Ptr ptrCat16(__uuidof(_clsCat16));
// Now we will intilize COM
hr = CoInitialize(0);
First of all, call CoInitialize _before_ you try to create
object's instance. CoInitialize should be called before any
COM related operations.
if(SUCCEEDED(hr))
{
bvalue = _clsCat16Ptr->Popup(bTheConnectString, bTheTable,
bTheFields, bThePopupTitle, bTheOrderBy, bTheWhereClause,
bThePosition,
bvalue);
^^^^^^
Last parameter is redundant. Popup method will return
_bstr_t as return value. Also, according to .TLH file Popup
method expects BSTR* parameters. So, you should call
_bstr_t::GetAddress method as I pointed in previous post:
bvalue = _clsCat16Ptr->Popup(
bTheConnectString.GetAddress(),
bTheTable.GetAddress(),
bTheFields.GetAddress(),
....);
Also, it's considered bad C++ style to declare variables far
from the place where they are used. It's much more elegant
and readable to declare variables when they first used, but
not earlier. For example, instead of declaring HRESULT hr in
the beginning of the function declare it where you call to
CoInitialize:
HRESULT hr = CoInitialize(0);
The same can be said about _bstr_t bvalue variable.
HTH
Alex