BSTR datatype? - OpenEdge Development - Forum

Posted by Admin on 16-Sep-2011 11:52

I'm working with an OCX that requires passing a pointer to a BSTR data type:

WORD mess[4] = {0x1,0x3,0x40,0x0};

BSTR pStringMessage = ::SysAllocString(mess);

Control.DirectIO(0,0,&pStringMessage);

I have tried various combinations of data types (char array, int array, memptr, etc) but I get "type mismatch" from the control.

For memptr, i am not sure how to construct BSTR. Any ideas / guidance is appreciated!

Thanks!

Posted by jmls on 18-Oct-2011 12:48

what version of Progress ?

Posted by Admin on 18-Oct-2011 13:06

10.2B

I was told that BSTR has something to do with putting the length to follow in the first two bytes, so I tried this...

DEFINE VARIABLE mpData AS MEMPTR.

SET-SIZE(mpData) = 17.

PUT-SHORT(mpData,1) = 2.

PUT-STRING(mpData,3) = "1".

PUT-SHORT(mpData,5) = 2.

PUT-STRING(mpData,7) = "3".

PUT-SHORT(mpData,9) = 3.

PUT-STRING(mpData,11) = "20".

PUT-SHORT(mpData,14) = 2.

PUT-STRING(mpData,16) = "0".

But it still doesn't work. I'm not sure if I have the byte offsets correct, or if this is the right approach at all.

Thanks for any idea!

Posted by jmls on 18-Oct-2011 13:32

Hmm. http://msdn.microsoft.com/en-us/library/ms221069(v=vs.85).aspx

says that the first 4 bytes are the length ...

Posted by Admin on 18-Oct-2011 14:09

Many thanks! This is exactly what I needed! (Don't ask why I couldn't find this...)

Cheers,

Steve

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