🚀 go-pugleaf

Muzzy wrote:

> Hi,
> 
> I have a .DLL library providing me with a function which returns false 
> or true depending on some conditions. It's declared in DLL as:
> 
> //----------------------
> extern "C" __declspec(dllexport) _stdcall bool VPNStart();
> //----------------------
> 
> 
> And i call it from an app (using func Start):
> 
> //----------------------
> typedef bool (*HVPNSTART)(void);
> 
> bool Start()
> {
>   HINSTANCE hLib = LoadLibrary("MyDLL.DLL");
>   if (hLib == NULL) {
>     MessageBox(0, "Unable to Load MyDLL.DLL", "Error", MB_OK);
>     return false;
>   }
>   HVPNSTART vs = (HVPNSTART)GetProcAddress(hLib, "VPNStart");
>   if (vs == NULL) {
>     MessageBox(0, "Failed calling VPNStart", "Error", MB_OK);
>     FreeLibrary(hLib);
>     return false;
>   }
>   bool result = vs();
> 
>   //MessageBox(0, "VPNStart Loaded!", "SUCCESS", MB_OK);
>   if (result) MessageBox(0, "TRUE", "RESULT", MB_OK);
>   else MessageBox(0, "FALSE", "RESULT", MB_OK);
> 
>   FreeLibrary(hLib);
>   return result;
> }
> //----------------------
> 
> Everything works perfect until... i add an argument to the DLL fucn 
> VPNStart:
> //----------------------
> extern "C" __declspec(dllexport) _stdcall bool VPNStart();
> //----------------------
> 
> So i change the main app code:
> //----------------------
> typedef bool (*HVPNSTART)(ShortString);
> bool Start( ShortString s ) {...}
> 
> 
> It starts to act WEIRD!!! When i trace (F8 -:)) thru the 'Start()' func 
> i see the following - after i load library, i write down it's address, 
> say ':013A000'.
> But after the line 'result = vs(s)', the hLib address changes to 
> ':8000004', and of course after i 'FreeLibrary' and return, it gives me 
> an access violation... How come the address of library handle could change?
> 
> I also tried to pass char* instead of ShortString, doesn't work also...
> 
> Any ideas, PLEASE!!!
> 
> Thank you,
> Andrey

Wow, i just made a very simple example of a dll func with "ShortString" 
arguement and it gives access violation as well... I can't use 
ShortString arguement to pass to a dll func? I am using BCB 6.0

Thank you,
Andrey