Re: EnumBands returns wrong value. Bug?
DHarray wrote:
Hello,
I want to enumerate my Band Objects with the use of IBandSite because i
need a special band id for my application:
_COM_SMARTPTR_TYPEDEF(IBandSite, __uuidof(IBandSite));
CoInitialize(NULL);
// ...
IBandSitePtr bs;
bs.CreateInstance(CLSID_TrayBandSiteService);
if (bs)
{
LONG count = bs->EnumBands(UINT(-1), 0);
Try:
DWORD Dummy;
HRESULT hr = bs->EnumBands ((UINT)-1, &Dummy);
and add
if (!SUCCEEDED (hr))
{
// Some error handling.
}
printf("%i",count); // -2147023116
Use the errlook tool that ships with Visual Studio to look up this error
code. It will tell you that you have passed a NULL pointer for a
top-level pointer, which is not allowed.
}
// ...
CoUninitialize();
Any idea why EnumBands returns a wrong value? MSDN said that the first
value has to be "-1" to get the number of bands. thanks for any help
Though the second parameter to EnumBands will be ignored, you cannot
pass a NULL pointer to the method (the call is made through a proxy
which check that all top-level pointers are valid).
This example shows that even Microsoft can create really, really awful
APIs. It would have been quite easy to introduce a method
HRESULT IBandSite::GetNumberOfBands ([out, retval] int* RetVal),
instead of this ugly 'When you pass a minus one as _unsigned int_
parameter!!!, you'll get this, else you'll get that humdrum. Take this
as an example of how to _not_ create an API.
Regards,
Stuart