call a unmanaged dll in ASP.NET app

[Priya]

Hi,
I'm developing an ASP.NET app. In codebehind .cs file i need call an
unmanaged C++ dll.I copied the dll into the bin directory.
the header file of the dll contains the definition as

extern "C" __declspec (dllexport) void FuelEfficiency( COleDateTime
m_dtFuelEffTo,C OleDateTime m_dtFuelEffFrom ,CString gSimID,char *itemp);

where itemp is out parameter
Declaration of function in C# is:

[DllImport ("VMMYDLL.dl l")]
public static extern void FuelEfficiency( DateTime m_dtFuelEffTo,D ateTime
m_dtFuelEffFrom ,string gSimID,[In,Out] char[] sb );
//calling function on a click event
private void StatSubmit_Serv erClick(object sender, System.EventArg s e)
{
DateTime temp = Convert.ToDateT ime(TxtFuelToDa te.Value);
DateTime temp1 = Convert.ToDateT ime(TxtFuelFrom Date.Value);
string st = null;
FuelEfficiency( temp,temp1,"919 444305923",st);//fn called
Response.Write( st);
}
I get an error :System.Runtime .InteropService s.SEHException: External
component has thrown an exception.
Is the above code correct?
Is there any way to debug unmanaged code in C#?

Thanks in advance
Priya

[CJ Taylor]

You might want to look into Marshaling..
"Priya" <Pr***@discussi ons.microsoft.c om> wrote in message
news:F3******** *************** ***********@mic rosoft.com...

Hi,
I'm developing an ASP.NET app. In codebehind .cs file i need call an
unmanaged C++ dll.I copied the dll into the bin directory.
the header file of the dll contains the definition as

extern "C" __declspec (dllexport) void FuelEfficiency( COleDateTime
m_dtFuelEffTo,C OleDateTime m_dtFuelEffFrom ,CString gSimID,char *itemp);

where itemp is out parameter
Declaration of function in C# is:

[DllImport ("VMMYDLL.dl l")]
public static extern void FuelEfficiency( DateTime m_dtFuelEffTo,D ateTime
m_dtFuelEffFrom ,string gSimID,[In,Out] char[] sb );
//calling function on a click event
private void StatSubmit_Serv erClick(object sender, System.EventArg s e)
{
DateTime temp = Convert.ToDateT ime(TxtFuelToDa te.Value);
DateTime temp1 = Convert.ToDateT ime(TxtFuelFrom Date.Value);
string st = null;
FuelEfficiency( temp,temp1,"919 444305923",st);//fn called
Response.Write( st);
}
I get an error :System.Runtime .InteropService s.SEHException: External
component has thrown an exception.
Is the above code correct?
Is there any way to debug unmanaged code in C#?

Thanks in advance
Priya