Using a Delphi native dll in C# (DllImport issue)

Question

I'm having issues importing a Delphi native dll to .net. I'm getting System.EntryPointNotFoundException .

Here's my delphi dll:

procedure ProcedimientoEncriptar(texto,clave,resultado:PChar); export stdcall;
    var ...
    begin
    ....
    ....
    end;

    exports
      ProcedimientoEncriptar ;

And here's my DllImport on .Net (C#) code:

[DllImport("CryptoDLL.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Auto)]
        public static extern void ProcedimientoEncriptar([MarshalAs(UnmanagedType.LPStr)]string texto, [MarshalAs(UnmanagedType.LPStr)]string clave, [MarshalAs(UnmanagedType.LPStr)] StringBuilder resultado);

Any help would be appreciated, Diego.

Answer 1

The only explanation for System.EntryPointNotFoundException is that the DLL that the C# code is finding is not the DLL produced from the Delphi code that you show. So, perhaps the C# code is picking up an out of date version of the DLL. Or perhaps it's picking up a completely different DLL.

For example, my system has a DLL named cryptdll.dll in the system32 directory. Most likely that's the DLL that your C# code is finding.

In order to make sure that the right DLL is found, you need to place a copy of the Delphi DLL in the same directory as the C# executable file.