It seems like a duplicate question from the title, but let me clarify that I have already searched and followed different methods.
Basically I have to import a managed C++ dll into a C# project. I consulted some tutorials and finally created a managed C++ dll. Now while importing the dll I got the following error:
An attempt was made to load a program with an incorrect format
I found some solutions like this but these solutions could not help me. Before facing this error I had to consult this solution and then this one too.
Here's a screenshot of how I am trying to import the dll:
Settings:
Code:
Someone please guide me about the right way to import the dll in my project.
This C++ library is for certain architecture (x64 or x86). C# on the other hand is not(Any CPU), that is why this kind of error - C# most likely assumes You have a x64 unmanaged library. You should restrict the architecture in C# project to either of these (x64 or x86) so in both projects they are the same.
Should you not be copying the file as a pre-build step? Make sure it is in the correct location before the build. I would also remove the exit 0, it's not needed.
That DllImport is usual for native C-style APIs, not the managed and C++/CLI assemblies. These .Net assemblies, be they mixed mode or not, can be added in the usual assembly dependency locations.
If this is a "Managed C++" and not a "C++/CLI" assembly, it may also be incompatible with the target .Net framework.
Related
Since I first heard about the introduction of Native AOT feature in .NET 7 and that it was usable on console executables and class libraries, I wanted to try out on some library projects I already had. Then, rised a problem I can't seem to workaround no matter the amount of research made. In fact after compiling successfully into a native dll, I don't know how to use it inside other .Net projects as it is no longer recognized as a .Net library type to be added as reference.
If anyone could enlighten me on how to access the methods compiled in that native dll from any other project in .Net, this could really mean a lot to me.
I have tried using the export attribute on public methods in the original library code to make them visible to external call. And then using import attribute on the caller project but nothing seem to work I can't see any public method from the generated dll.
I have a source file written in C++, performing some simulation. I would like to create a user interface for this in C#. How can I have both C++ and C# in a single Visual Studio solution?
What I did so far was I created a .NET C# project and solution, and then a native project as a DLL library. I have marked the C# project as "Depends on" the C++ dll. I have provided the necessary dllexport directives and imported using DllImport. Everything compiles fine, but when I execute the application, the dll is not found:
Unable to load DLL 'xxxx.dll': The specified module could not be found.
It is no surprise the DLL is not found, as the application is run from its output directory and the output directories are different for the C# and C++ projects. I do not want to write an explicit path as my import like `"..\..\Debug\xxxxx.dll".
Is there some common way how to structure a solution containing native a Dll and C# app so that the C# app can call the native Dll?
If you know that after deployment your C++ DLL will be in the same folder as your C# DLL (or executable), then on simple way to solve the problem is to use the PostBuild event (Project properties, Build events).
You can add a copy command that will put your C++ DLL into the C# output folder.
I found a very comfortable way, which might have some unexpected drawbacks, but I do not see any so far: I can enable CLR for the C++ DLL project, making it "mixed", even if it in fact does not contain any managed code, and then the project building it can be made a Reference in the C# .NET project.
To make the project mixed mode set Configuration Properties / General / Common Language Runtime Support to Common Language Runtime Support (/clr).
After this the build system copies the DLL into the application output folder automatically.
i have received a wrapper class for a C++ unmanaged code, which i need to add to my web project and call through c#.
1) in a c# desktop application project
When i'm adding references i can only add the wrapper dll. cannot add the unmanaged dll. i think this is not a issue. Then when i'm buliding and running it gives an error saying
Could not load file or assembly 'AskCmnWrapper.DLL' or one of its dependencies. The specified module could not be found.
So then i manually copied my unmanaged dll to the bin folder . It worked fine
2) in a c# web application
i got the same above issue. manually copied my unmanaged dll to the bin folder when i'm trying to run it with iis express (through vs2012) . but it's not working. Is there any special configurations to be made when running unmanaged dll/wrappers in web applications?
please guide me.
thank you.
Chances are you are missing some of the required C++ redistributables or other dependencies. Run Dependendy Walker on your native DLL to see which ones are are missing.
Ideally, you want to make a C++/CLI project which contains the source code of the native library you are wrapping, and write a managed C++/CLI wrapper on top of it, in the same project. This way only the "wrapper" (containing the native code) will be required in your folder.
If you don't have the source, and you can not statically link the library into your C++/CLI project, you will need to have both the wrapper DLL and the native DLL in the directory at run time, as that's when they will be linked.
I'm using Microsoft C# 2010 Express with the FrameLink Express drivers from Imperx. When I try to load the DLL at runtime, I get an exception:
Unable to load DLL 'VCECLB.dll': The specified module could not be
found. (Exception from HRESULT:0x8007007E)
If I try to add the DLL as a reference, I get this message:
A reference to 'C:\\VCECLB.dll' could not be added. Please
make sure that the file is accessible, and that it is a valid assembly
or COM component.
Two questions:
Is this an Express problem (i.e. some limitation with Express causing the problem)? I believe the source for the DLL is written in C++, but I wouldn't think that would matter.
Is there a different way to reference the DLL and/or add it to the project? Something I'm doing wrong?
Finally, I've tried adding both the x86 and x64 versions, debug and release. Same failure to add as a reference every time.
That DLL doesn't seem to be .NET (nor COM) code - therefore you cannot load it, nor add a reference to it.
Doesn't have anything to do with your Express version - it's just not a .NET "compatible" DLL and thus you can't load or reference it.
In order to use its functionality, you'll probably have to dive into more "arcane" (and more elaborate and more complicated) methods of calling raw C++ code from .NET - or find a .NET compatible counterpart or version of it.
Actually, the answer appears to be in the first line of the message:
Unable to load DLL 'VCECLB.dll': The specified module could not be found. (Exception from HRESULT:0x8007007E
It says it cannot find the DLL, not that the DLL is not compatible.
The DLL should be located with the other DLLs with your program, and you need to add the DLL to the solution.
If by some chance the DLL is compiled as Native C/C++ (i.e., Not .NET style), it can be called from a C/C++ that is a .NET style, but not a C# routine.
So, if the problem is that the module can be found but not loaded, you need to write a C++ (.NET) routine to call from your C# routine (.NET) to call the C++ (Not .NET).
All code that talks directly to hardware must do this at some level. Most do this for you using multiple DLLs.
I want to use c++ library in a c# project. Is there any wrapper tool to import all classes automatically?
SWIG can help create a wrapper consisting of two parts, one C++ sided, and one C# sided.
It needs a bit of work to set up the correct generation files though.
An alternative that requires more manual coding is C++/CLI.
For pure c apis I prefer p/invoke over either of them. There is a program to automate conversion of c headers. If I recall correctly it's called something like "P/Invoke Interop Assistant" or "Interop Signature Toolkit".
There is also mono/cxxi which looks pretty cool.
The procedure of using native .dll's in .Net is called P/Invoke. Look at http://pinvoke.net/ for some examples.
Note that you must match the build target with the version of the .dll. So for x86 .dll's you need to lock your project to x86, same with x64.
Note2 that you only need to lock the executing project (.EXE), not any additional projects loaded from the .EXE. .Net will automatically match .Net .dll's to CPU target type if they are set to ANY.
From http://social.msdn.microsoft.com/forums/en-US/clr/thread/c957959e-0f0c-422e-a5be-4ccfdd12e63d: You can use "dumpbin /exports <name_of_your_dll>" or dependency walker (depends.exe) to look at the exported symbols. They are both included in Visual Studio.
Additional comment on C++: While it is relatively simple to use native .dll's written in C from .Net, using C++ binaries that make use of objects is not as trivial. One way to solve that is to use a C++ CLI project a binding between managed .Net code and unmanaged C++ library.
If this is unmanaged code then you could use P/Invoke. Another possibility is to use the C++/CLI extensions to compile the code into a managed assembly that you could directly use.