Resizing VB6 string

[Edwin Knoppert]

Hello,

I know VB and PB strings are interchangable.
I just wrote a VB6 and PB6 app and DLL to fill a VB's string from within the DLL.
It seems to work fine.

Are there any problems i might encounter?

Both procedures uses the string byref

Like;
Declare Function MyDLLFunc Lib"MYDLL.DLL"( sdata As String ) As Long

??


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[Tony Altwies]

I would be careful. VB Strings are OLE compliant and
you should use the "SysString" family of functions to
create and return strings to VB. There is also a document
that describes the proper conventions of usage.

VB uses the Unicode (double byte) versions of strings
internally and then copies and creates the single byte
versions when they are passed to DLL's. This is also
true if the strings are contained in UDT's. When the
DLL returns, VB reconstructs the Unicode versions.

It is possible that if you are writing into the memory
pointed to by a string, that it might move during garbage
collection, thus causing a GPF.

I hope that all of this doesn't discourage you because it
is valuable to be able to use variable length strings as
arguments to DLL's - Just follow the rules!

Regards,

Tony



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[Lance Edmonds]

Be sure to review the FAQ on VB strings in the FAQ forum, and in the "Working with Visual Basic" section of the PB help file.


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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>