passing strings VB.net to PB9

[Kerry Goodin]

sending a string to a DLL I made a function in the DLL:

FUNCTION ReverseString ALIAS "ReverseString" (BYVAL X AS STRING) EXPORT AS STRING
MSGBOX X
A$ = X
MSGBOX A$
S$ = STRREVERSE$(X)
FUNCTION = S$ + " test dll"
END FUNCTION

the first message box shows the string the second shows blanks and the only thing that comes back from the function is " test dll"

the declare in VB.NET is:

<DllImport("TESTDLL.DLL")> _
Public Shared Function ReverseString(ByVal X As String) As String
End Function

Does anyone have an answer in passing a string to a native DLL?


Thanks

[Walt Thompson]

Passing Strings

Hi Kerry;

'This should work.
FUNCTION ReverseString ALIAS "ReverseString" (BYREF X AS STRING) EXPORT AS STRING

'Items passed BYVAL cannot be changed.
FUNCTION ReverseString ALIAS "ReverseString" (BYVAL X AS STRING) EXPORT AS STRING

[Kerry Goodin]

Hi Kerry;

'This should work.
FUNCTION ReverseString ALIAS "ReverseString" (BYREF X AS STRING) EXPORT AS STRING

'Items passed BYVAL cannot be changed.
FUNCTION ReverseString ALIAS "ReverseString" (BYVAL X AS STRING) EXPORT AS STRING

I do not need to pass back the variable in the parameter the function sends the string back.

Thanks.

[Eddy Van Esch]

Kerry,

The code below seems to work for me with:
- PBWin 9.0 for the dll
- Visual Basic 2005 Express Edition for the calling program.

the PB dll:

#COMPILE DLL "Test.dll"
#DIM ALL
#INCLUDE "Win32Api.Inc"

FUNCTION ReverseString ALIAS "ReverseString" (BYVAL X AS STRING) EXPORT AS STRING
    LOCAL S$
    S$ = STRREVERSE$(X)
    MSGBOX "In PB dll:" + S$
    FUNCTION = S$ + " test dll"
END FUNCTION 


'--------------------------------------------------------------
FUNCTION LIBMAIN(BYVAL hInstance AS DWORD, BYVAL fwdReason AS DWORD, BYVAL lpvReserved AS DWORD) EXPORT AS LONG
    LIBMAIN = 1
END FUNCTION
'--------------------------------------------------------------

The VB code in Form1.vb:

[B]Imports System.Threading
Imports System.Runtime.InteropServices[/B]

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim sS As String
        sS = "Eddy"
        MsgBox("Answer of dll:" + [B]MyClss[/B].ReverseString(sS))
    End Sub
End Class

Add a class module to your VB project:

Public Class [B]MyClss[/B]

    Declare [B]Ansi [/B]Function ReverseString Lib "Test.dll" (ByVal a As String) As String

End Class

Kind regards

[Kerry Goodin]

That did it.

Thanks, I knew I could count on you guys!!

Kerry