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Unmanaged Exports not showing up in DLL

I have a new project and a test class, method below:
[ComVisible(true)]
[DllExport("Heartbeat2", CallingConvention = CallingConvention.StdCall)]
public static void Heartbeat2(){
//Do stuff here
}
Im using Unmanaged Exports (RGiesecke.DllExport) latest in DotNet 4.6...when running Nirsofts viewer, I do not see my method in the dll http://www.nirsoft.net/utils/dll_export_viewer.html)
I have the platform target to x86 also...what am I doing wrong? I plan on using this in a ruby 1.8.1 program using Win32API

Giesecke's Unmanaged Exports works fine using VS2015, but not in VS2017 or VS2019.
Try downloading VS2015 Community and try your example there.
Be sure you are building for X64 or X86, not Any CPU.
The Unmanaged Exports should generate a DLL, plus a LIB and RES file.
You can check whether the DLL was modified by checking it with one of several fine .Net decompilers, my current favourite is https://www.jetbrains.com/decompiler/

Import DLL c++ on VSC# 2010 (AdminPaq SDK )

I'm trying to import a library to my WCF project, the DLL was provided by Adminpaq.
i'm using the next following code:
[DllImport("MGW_SDK.dll", EntryPoint = "fInicializaSDK")]
public static extern int fInicializaSDK();
When i debug the app say the next error : Unable to load DLL The specified module could not be found.
I've ready on web that the error could be by dependece but on the SDK documentation display a list of some files that must be added to the root project i'm currently adding al of them
Some info:
Dll is build on: c++
Proyect type: c# Application service MCF
I'm using: Windows 7 ultimate x64
Any further information required please don't hesitate to ask.

You are right, usually it is related to some other library that your MGW_SDK.dll depends on. Try these:
1) Install the Microsoft Visual C++ redist (2005, 2008 or 2010, depending on which VS was used to build that dll)
2) If that does not help, try using dependency walker tool to see which files are missing (http://www.dependencywalker.com)
I hope that helps.

You must type the full and original path of the DLL, for example: #"C:\Program Files (x86)\Compacw\AdminPAQ\MGW_SDK.dll"

you must install AdminPaq and have a registered license, after that the error will dissapear

Class not registered error from PHP

We've created a C# class library assembly and made it COM visible to be able to call its methods from PHP. This used to work fine, but now we wanted to install it on a Windows Server 2008 server and we keep walking into the error "Class not registered".
To rule out any dependency problems I made a tiny little test class library in C#. The class library is built for Any CPU and it is COM visible (also set COMVisible to true in AssemblyInfo.cs). The test class library only contains one class with one method. The class is called TestLib and the namespace is also called TestLib. The method is called Test and only returns a string.
What we have done is the following:
- built the TestLib.dll
- copied it to the Windows Server 2008 machine
- registered the dll with: regasm /codebase TestLib.dll
- the regasm tool returns a success message
- in PHP we simply try to create a new COM instance:
try
{
$test = new COM("TestLib.TestLib");
}
catch (Exception $e)
{
die($e->getMessage());
}
when we call this test script from either the browser or the commandline (php -f test.php) we get the error "Class not registered" in both cases
I also tried adding TestLib to the GAC by using gacutil -i, but to no avail; still the class not registered error.
Then I tried compiling the testlibrary with .NET 2.0 instead of 4.0 as the target framework, same result. The .NET framework 4.0 is installed on the server by the way.
Any ideas?

Okay, so after some more research I figured it out. The php.exe process is 32 bit. The COM visible assembly is compiled for Any CPU so it should be accessible to both 32 and 64 bit applications.
The problem is that on a 64 bit OS php.exe, and any 32 bit process for that matter, searches in HKEY_CLASSES_ROOT\Wow6432Node\CLSID instead of HKEY_CLASSES_ROOT\CLSID and in HKEY_LOCAL_MACHINE\Software\Classes\Wow6432Node\CLSID instead of HKEY_LOCAL_MACHINE\Software\Classes\CLSID. The registry entries in the Wow6432 keys aren't created by regasm that is shipped with .NET framework v4 on Windows Server 2008. On Windows 7 they are created, don't ask me why.
It also turned out that if I create a little test assembly for .NET v2.0 and register it with regasm that ships with .NET framework v2.0 that it does create the Wow6432Node entries on Windows 2008. Strange.
So my solution is to create a basic registry file on the server using:
regasm /regfile MyClassLib.dll
This creates a file MyClassLib.reg with only the 'normal' 64 bit entries. Then I exported the Wow6432Node keys from a Windows 7 machine and added it to that .reg file. Now when I import that reg file into the registry on Windows 2008 everything works fine.
For more info on the Wow6432Node entries check out: http://msdn.microsoft.com/en-us/library/windows/desktop/ms724072%28v=vs.85%29.aspx
Hope this saves someone else some time and headaches.

If you are trying to call a 32-bit COM DLL on 64-bit Windows, you will need to register it.
Copy your 32-bit DLL to C:\Windows\sysWOW64
Run C:\Windows\sysWOW64\regsvr32.exe your_com_32.dll
A bit more info with screenshots.

Call into 64bit Dephi DLL from C# on 64bit Machine

I my c# app I am trying to call into a Delphi DLL build as 64bit. I keep getting an error stating "An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B". I am running on a Windows 7 64 bit machine and have my C# project set to Any CPU.
API call
[DllImport("Cipher.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.ThisCall)]
public static extern void Encrypt(StringBuilder szPlainText, StringBuilder zCipherText);
Encrypt(plainString, encText);
If the Delphi DLL was build as 32bit this call works fine. Any ideas?

For some reason your app is not run as a 64-bit but rather a 32-bit process. If you need to do things like this, it's better to specify "x64" instead of "AnyCPU".

BadImageFormatException: PInvoke ImportDll with hdf5dll.dll

Ok, I have the HDF5 library downloaded from the official site, and I have a few DLLs, including hdf5dll.dll, and hdf5_hldll.dll.
I have what I think to be some wrappers around the native calls, in my classes H5, H5LT, H5F, and H5T. Example from H5.cs:
namespace HDF5
{
using hid_t = System.Int32;
using herr_t = System.Int32;
using hsize_t = System.UInt64;
using size_t = System.UInt32;
// hbool_t is 0:false, +:true
using hbool_t = System.UInt32;
// htri_t is 0:false, +:true, -:failure
using htri_t = System.Int32;
public class H5
{
const CharSet StringMarshallingType = CharSet.Ansi;
const string DLLNAME = "hdf5dll.dll";
///* Functions in H5.c */
//H5_DLL herr_t H5open(void);
[DllImport(DLLNAME,
CharSet = StringMarshallingType)]
public static extern herr_t H5open();
And in Program.cs, I use H5.H5open();, but I get a BadImageFormatException. Do I need a different DLL? Does the method signature look wrong?
I'd like to, as the next step, get this in C#: http://www.hdfgroup.org/HDF5/Tutor/h5lite.html .
OS: Windows 7 64 bit
Environment: Visual Studio 2008 Professional
Update: I don't know if this will be related, and I don't remember if my environment is VS2008 SP1, but this question may hold a key to solving the mystery. I am as of now trying to repeat the scenario on 32 bit VS 2010 at home.

That happens when you're trying to run P/Invoke operations on a dll meant for x86 architecture from within an x64 process or vice versa. I'd check all of that and if they're out of sync, consider targeting the processor that HDF5 targets with your application, or checking if a processor-specific version is available.

Looking at the documentation from here, the function prototype is:
herr_t H5open(void);
And also the DLLNAME is disallowed, you must explicitly specify the dll name - no questions asked.
The proper signature is:
[DllImport("hdf5dll.dll")]public static extern herr_t H5open();
Make sure you have the type herr_t defined...
Let the runtime take care of the marshalling for you....
Also make sure, the DLL is present in the same path as where the compiled .EXE (your code) is generated.
Edit: Thanks to the OP for pointing out my blooper....

On x64 operatingsystems .net programs usually run in x64 mode.
Just set your target processor architecture to x86 and try again.
Just in Visual studio open your "Solution Configuration"-Manager and add a new target Platform.