Handling C++ DLL string pointer

[penguin]

All,

I have a C++ DLL that has the following function in it.

LONG MYAPI myApi_FunctionN ame
(
LONG lDSType, /* i Source type */
LPWSTR lptstrSource, /* io Source name */
LONG lDSLength, /* i Length of lptstrSource */
LPCWSTR lpctstrCat, /* i Catalogue */
LPCWSTR lpctstrSubj /* i Subject */
);

I have the following declared in my VB2005 module.

Public Declare Unicode Function myApi_FunctionN ame Lib "mydll.dll" (ByVal lDSType As Integer, _
ByRef lptstrSource As Integer, _
ByVal lDSLength As Integer, _
ByVal lpctstrCat As String, _
ByVal lpctstrSubj As String) As Integer

If I declare lptstrSource as Integer, I get a numeric value. I believe it is the pointer address. The question is, how do I get the actual "Source name" string (i.e. lptstrSource)?
I have tried passing lptstrSource as String. However, it is always empty.

Thanks,

alex

[Mattias Sjögren]

Re: Handling C++ DLL string pointer

>If I declare lptstrSource as Integer, I get a numeric value. I believe it is the pointer address. The question is, how do I get the actual "Source name" string (i.e. lptstrSource)?

>I have tried passing lptstrSource as String. However, it is always empty.

The string should be passed ByVal. If it's an output parameter,
consider using the StringBuilder type instead.


Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[penguin]

Re: Handling C++ DLL string pointer

Mattias,

It works perfectly. Thanks a lot.

^_^

alex


"Mattias Sjogren" <mattias.dont.w ant.spam@mvps.o rgwrote in message
news:eb$I4ulyGH A.3428@TK2MSFTN GP02.phx.gbl...

If I declare lptstrSource as Integer, I get a numeric value. I believe it
is the pointer address. The question is, how do I get the actual "Source
name" string (i.e. lptstrSource)?
>>I have tried passing lptstrSource as String. However, it is always empty.

>
The string should be passed ByVal. If it's an output parameter,
consider using the StringBuilder type instead.
>
>
Mattias
>
--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.