Question

I have 3 projects in one solution.

I have :

• a native C++ dll,
• a C# Winform,
• and a proxy C++/CLI without pure mode to do the link between the 2 others projects (and use the native function in the managed code in C#)

So when I launch the application all work. But when I push the button "Generer" in my winform wich execute the function NativeMethod::Test() of the C++/CLI that it crash and I have this pop-up message :

An unhandled exception of type
‘System.BadImageFormatException’
occurred in System.Windows.Forms.dll

Additional information: Could not load
file or assembly
‘EngineInterfaceWrapper.dll’ or one of
its dependencies. n’est pas une
application Win32 valide. (Exception
from HRESULT: 0x800700C1)

When I go in project proprieties in Conf. Properties -> Linker -> Advanced : Target Machine, it’s set with the value "MachineX86" for my C++ native and managed DLL and my WinForm is in X86 too. I tired many configurations but it don’t work.

Edit:

The problem is may be the header "TradeEngine.h"" in the C++/CLI header : EngineInterfaceWrapper.h. Because when I unlink the native C++ Dll (and deleting all code in the CLI wrapper) if I build the solution it will work but if "#include "TradeEngine.h"" is always in the CLI header, I will have the same error. Do you have an idea?

Code :

native C++

TradeEngine.h

#ifdef TRADEENGINE_EXPORTS
#define SYMBOL_DECLSPEC __declspec(dllexport)
#define SYMBOL_DEF
#else
#define SYMBOL_DECLSPEC __declspec(dllimport)
#define SYMBOL_DEF      __declspec(dllimport)
#endif

EXTERN_C SYMBOL_DECLSPEC void __stdcall Test(void);

TradeEngine.cpp

SYMBOL_DECLSPEC void __stdcall Test(void)
{
}

C++/CLI

EngineInterfaceWrapper.h

#pragma once

#include "TradeEngine.h"

using namespace System;
using namespace System::Runtime::InteropServices;

namespace EngineInterfaceWrapper {

    public ref class NativeMethod
    {
    public:
        static void AjoutColonneDifferenceCourtClotureOuvertureReelle(void);
        static void Test();
    };
}

EngineInterfaceWrapper.cpp

#pragma region Includes
#include "stdafx.h"
#include "EngineInterfaceWrapper.h"
using namespace EngineInterfaceWrapper;

#include <msclr/marshal.h>
using namespace msclr::interop;
#pragma endregion

void NativeMethod::Test()
{
    ::Test();
}

C# Winform

Program.cs

namespace TradeInterface
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

Form1.cs

generer_Click() is the event launched by the button when the user click on Generer.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

using System.Runtime.InteropServices;
using EngineInterfaceWrapper;

namespace TradeInterface
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void generer_Click(object sender, EventArgs e)
        {
            NativeMethod.Test();
        }
    }
}

How can I fix that? If you need more info, tell me.

Answer 1

One reason can be you are trying to load a native 32-bit dll in a 64-bit process. Make sure you have platform target set to x86 in your app to force your application to run inside WoW64.