Submit My Question - Recent Questions - Recent Answer
Msdn Tech >> Visual Basic >> Visual Basic Language

BSTR type in VB

I received a DLL which uses BSTR as string type:

example : given in the include file

DLLEXPORT BSTR WINAPI I2cGetInterfaceTypeStr (BSTR Interface);

how do i access this function in vb. This doesn't work.

DeclareFunction I2cGetInterfaceTypeStrLib "I2CAPI32.DLL" (ByVal InterfaceTypeAsString)AsString

Other functions of the DLL which don't use BSTR are working ok.

Can anyone help me.

Thanks, Jan
[976 byte] By [jan_hk] at [2008-2-5]
«« BSTR type in vc#
»» Build Server
# 1

Have you tried something like:



Declare Function I2cGetInterfaceTypeStr Lib "I2CAPI32.DLL" (<System.Runtime.InteropServices.MarshalAs(Runtime.InteropServices.UnmanagedType.BStr)> ByVal InterfaceType As String) As <System.Runtime.InteropServices.MarshalAs(Runtime.InteropServices.UnmanagedType.BStr)> String



Best regards,
Johan Stenberg

JohanStenberg at 2007-9-8 > top of Msdn Tech,Visual Basic,Visual Basic Language...
# 2
Hello Johan

My question was not complete. I discovered i have only a problem with empty string.
I have next C++ example

// get first interface from the registry
// (first interface is returned when passing an empty string ! )
InterfaceGUID = I2cGetNextInterface( (BSTR)(""));
while(1)
{
// compare the interface found in the registry with ’cIFType’ (the one we want to use )
if (!strcmp(cIFType, (const char*)I2cGetInterfaceTypeStr(InterfaceGUID)))
break;

FirstGUID = I2cGetNextInterface("{00DA5BA0-2540-11d1-8110-00400534438D}") ' this works gives the next string

FirstGUID = I2cGetNextInterface("") ' this returns also empty string

regards, Jan

jan_hk at 2007-9-8 > top of Msdn Tech,Visual Basic,Visual Basic Language...
# 3
Is it possible that GetNextInterface argument is meant to be the buffer it will write the value back to you? In that case if you provide it with something that can hold a guid it would work, and if you gave it an empty string it wouldn't have enough space and thus just return the empty string again.
AlexMoura at 2007-9-8 > top of Msdn Tech,Visual Basic,Visual Basic Language...
Visual Basic
Visual Basic Language

Visual Basic Hot Topic

Visual Basic New Topic

Visual Basic

Java / MSDN / Linux Tech / PHP Tech / MSDN DotNet / MSDN TECH / Health Library / Programmers Tech / visual basic Tech / Developer Tech / Ipod faqs / Msdn China Tech

Site Classified