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GeneralRe: Question about VARIANT deallocation Pin
Hristo-Bojilov10-Aug-09 6:45
Hristo-Bojilov10-Aug-09 6:45 
GeneralRe: Question about VARIANT deallocation Pin
GuimaSun10-Aug-09 7:08
GuimaSun10-Aug-09 7:08 
AnswerRe: Question about VARIANT deallocation Pin
Stuart Dootson10-Aug-09 8:21
professionalStuart Dootson10-Aug-09 8:21 
GeneralRe: Question about VARIANT deallocation Pin
GuimaSun10-Aug-09 8:43
GuimaSun10-Aug-09 8:43 
AnswerRe: Question about VARIANT deallocation Pin
Vi210-Aug-09 22:01
Vi210-Aug-09 22:01 
GeneralRe: Question about VARIANT deallocation Pin
GuimaSun12-Aug-09 4:12
GuimaSun12-Aug-09 4:12 
GeneralRe: Question about VARIANT deallocation Pin
Vi212-Aug-09 21:37
Vi212-Aug-09 21:37 
GeneralRe: Question about VARIANT deallocation Pin
Vi213-Aug-09 0:20
Vi213-Aug-09 0:20 
About memory leaks. VB allocation\dellocation mechanisms are the same with COM.
p->vt = VT_BSTR | VT_BYREF;
BSTR *pBSTR = new BSTR;
*pBSTR = SysAllocString( L"abc" );
p->pbstrVal = pBSTR;

There are 2 memory allocations in statements "= new BSTR" and "= SysAllocString".

The VARIANT with VT_BYREF|VT_BSTR isn't an owner of its values, so freeing of the VARIANT doesn't free neither pbstrVal nor *pbstrVal. And finally you have memory leaks.

The VARIANT with VT_BSTR (without VT_BYREF) is an owner of its values, so freeing of the VARIANT frees bstrVal.
p->vt = VT_BSTR;
p->bstrVal = SysAllocString( L"abc" );

And there are no memory leaks.

With best wishes,
Vita

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