parameters on dll

[SiaMeX]

I know that this will be very easy for you guys...

'==========================================================
'MY VB CODE
'==========================================================
Private Declare Sub MyFunction Lib "MyDLL.dll" (ByVal MyParameter As String) As Integer

Private Sub TestFunc ()
    MyParameter = "Original String"
    MyFunction MyParameter 
    Msgbox MyParameter        -----> string should now be
                                                  "String Overwritten"
End Sub
===========================================================

After passing thru my MyFunction, the variable (MyPrameter) should now be overwritten by that previously called function. I have my Mydll.dll code below that i think there's something missing with it. Please help my with this code.

//=========================================================
//MyDll.dll in C/C++ CODE:
//=========================================================

#include ...
     .
     .
     .
int __cdeclspec CALLBACK MyFunction (LPSTR MyParameter)
{
     strcpy (MyParameter, "Sting Overwritten");
     return 0;
}
//=========================================================

thank you so much!

 

[SiaMeX]

sorry!

int __cdeclspec CALLBACK MyFunction (LPSTR MyParameter)

this should be:

int __declspec (dllexport) CALLBACK MyFunction (LPSTR MyParameter)

 

[aakhrinaam]

Effectively you are passing a local variable to a function by value , not by reference .
If you want your original string overwritten pass a pointer to it ( by reference) or other wise make that function return a string ( I would go with the former option).