eVC .dll in vb.net on PocketPC 2003

[Guest]

I am having trouble accessing a .dll created in eVC through vb.net. The function for the .dll looks like the following in eVC

__declspec(dllexport
int WINAPI foo3 (int inval

return inval+10


Inside of my VB appliation, I have the following

Imports System.Runtime.InteropService

<DllImport("CProcess.DLL")>
Public Function foo3(ByVal foo As Integer) As Intege
End Functio

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Clic
Dim retval As Intege
Dim inVal As Intege

retval = foo3(inVal
inVal = 1
retval = foo3(inVal
retval = foo4(inVal
End Su
End Clas

The first call to foo3 returns correctly (inVal = 0, retVal = 10). However, on the second call to foo3, the PDA reports "A native exception occurred. ExceptionCode: 0x80000002 ...". The PDA seems to be complaining about data not being aligned properly. Can anyone help me figure this one out? I've got plenty of VC++ experience, but am new to VB and the PDA world. Thanks.

 

[Chris Tacke, eMVP]

You're certain that's all the code in the C++ method? It sure sounds like
it's stepping on memory somewhere.

-Chris

I am having trouble accessing a .dll created in eVC through vb.net. The

function for the .dll looks like the following in eVC:

__declspec(dllexport)
int WINAPI foo3 (int inval)
{
return inval+10;
}


Inside of my VB appliation, I have the following:

Imports System.Runtime.InteropServices

<DllImport("CProcess.DLL")> _
Public Function foo3(ByVal foo As Integer) As Integer
End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles Button1.Click

Dim retval As Integer
Dim inVal As Integer

retval = foo3(inVal)
inVal = 10
retval = foo3(inVal)
retval = foo4(inVal)
End Sub
End Class

The first call to foo3 returns correctly (inVal = 0, retVal = 10).

However, on the second call to foo3, the PDA reports "A native exception
occurred. ExceptionCode: 0x80000002 ...". The PDA seems to be complaining
about data not being aligned properly. Can anyone help me figure this one
out? I've got plenty of VC++ experience, but am new to VB and the PDA
world. Thanks.

 

[Chris Tacke, eMVP]

I don't see any problem with your code. The DLL is built for the right
processor, right?


--
Chris Tacke, eMVP
Co-Founder and Advisory Board Member
www.OpenNETCF.org
---
---
Principal Partner
OpenNETCF Consulting
www.OpenNETCF.com

Yes. That is all the code in my method. I've now gotten it to work by

adding Imports System to my VB app, and changing the foo3 function
declaration to

<DllImport("CProcess.dll", CharSet:=CharSet.Unicode, EntryPoint:="foo3")> _
Public Shared Function foo3(ByVal foo As Integer) As Integer
End Function

I have no idea why this has made a difference, but it has.

However, I am now having trouble passing data by reference. I now have a function foo4

__declspec(dllexport)
void WINAPI foo4 (long *inval)
{
*inval = 32;
}

With corresponding VB code

<DllImport("CProcess.DLL", CharSet:=CharSet.Unicode, EntryPoint:="foo4")> _
Public Sub foo4(ByRef foo As Long)
End Sub

And once again, when I call the function foo4, I get an exception "A

native exception occurred. ExceptionCode: 0xc0000005 ..."

All of the example code I've seen on the web does it this way, and I

cannot figure out why this isn't working.