MissingMethodException - c++ unmanaged call

[kritho]

Hi,

I am trying to call an unmanaged funcrtion from a simple eMbedded Visual C++ dll, but I only get the MissingMethodException. This is the first time I'm trying do use unmanaged code. Here is a sample of my code:

c++ dll:

header file:


#ifdef TTWRAPPER_EXPORTS
#define TTWRAPPER_API __declspec(dllexport)
#else
#define TTWRAPPER_API __declspec(dllimport)
#endif

// This class is exported from the ttwrapper.dll
class TTWRAPPER_API CTtwrapper {
public:
CTtwrapper(void);
// TODO: add your methods here.
};

extern TTWRAPPER_API int nTtwrapper;

#ifdef __cplusplus
extern "C"
{
#endif

TTWRAPPER_API int fnTtwrapper();

#ifdef __cplusplus
} // extern "C"
#endif


cpp file:

#include "stdafx.h"
#include "ttwrapper.h"

BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}

TTWRAPPER_API int nTtwrapper=0;

TTWRAPPER_API int fnTtwrapper()
{
int t = 15;
return t;
}


CTtwrapper::CTtwrapper()
{
return;
}



my simple C# device app:

using System.Runtime.InteropServices;
using System;
using System.Drawing;
using System.Collections;
using System.Windows.Forms;
using System.Data;

namespace Managed
{

public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.TextBox textBox2;
private System.Windows.Forms.MainMenu mainMenu1;

[DllImport("ttwrapper.dll", EntryPoint="fnTtwrapper")]
public static extern int fnTtwrapper();

public Form1()
{

InitializeComponent();

}


static void Main()
{
Application.Run(new Form1());
}

private void button1_Click(object sender, System.EventArgs e)
{
try
{
int i = fnTtwrapper();
this.textBox1.Text = "taller er: " + i;
}
catch(Exception ex)
{
this.textBox2.Text = ex.Message;
}
}
}
}

Read that many ask for DUMPBIN exports, this is:

Section contains the following exports for ttwrapper.dll

00000000 characteristics
42819B5C time date stamp Wed May 11 07:42:52 2005
0.00 version
1 ordinal base
4 number of functions
4 number of names

ordinal hint RVA name

1 0 00001030 ??0CTtwrapper@@QAA@XZ
2 1 00001000 ??4CTtwrapper@@QAAAAV0@ABV0@@Z
3 2 00003028 ?nTtwrapper@@3HA
4 3 00001028 fnTtwrapper

Summary

1000 .data
1000 .pdata
1000 .rdata
1000 .reloc
1000 .text




Anyone who can help me?? I'm testing on a real device via visual studio .net 03

Thomas

[darwen]

Sounds like you're dll isn't exporting the method properly. I use the .def file method for writing dlls - I find it's more reliable.

If you look at your dll in depends.exe I think you'll find your method isn't there. Which is why your C# app can't find the method.

Darwen.

[kritho]

Hi Darwen, thanks for you reply, but I could need som more help.

I can see the method, but get some other error. You can see my a screen capture from depends. Can you give an example the .def file, or guide me where I can find out more about it.

http://www.guttaboys.net/unmanaged/depend.htm

Thomas