Is there a way to call c# dll from c++ unmanaged application without COM usage?
You can do this using Reverse P/Invoke - example and discussion here.
It is actually possible to disassemble, modify the IL, and reassemble it with exported functions. I messed with this a few years ago, and created an application that would disassemble a dll, provide a list of functions that could potentially be exported - allowing the user to select them, then re-write the IL and reassemble everything. Then, I could call directly into the dll from unmanaged code...or p-invoke into the dll from managed code (not really practical, but interesting nonetheless).
Surely there is a reason that this isn't supported in the .net languages themselves (even tho it is supported in MSIL). I wouldn't use this in production:
Dead link:
http://www.csharphelp.com/2007/03/exporting-managed-code-as-unmanaged/
Wayback Machine:
https://web.archive.org/web/20140213030149/http://www.csharphelp.com/2007/03/exporting-managed-code-as-unmanaged/
I might be a bit late, but check this out.
Using this little msbuild task, you can create a C# library that can be called as if it were a native DLL. (e.g. write plugins for apps that require them to be native dlls)
Oh and don't forget to use the project template, which will setup everything for you.
Your only option really is to either use C++.net or create a C++.net wrapper for it that exports what you need.
Calling C# code from C++
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I'm working on a C# project at the moment and I have zero experience with C#.
We have a set of DLLs written in C++, they have the same classes and same functionality, but they work differently. As an instance let's say our program converts BMP files. We have DLLs for converting BMP to JPG, BMP to PNG and so forth.
Our program which is written in C# somehow should wrap those DLLs, but not in a static way. We'd like to be able to change the DLL in use during runtime, and add new DLLs when need be (also during runtime). Like plugins, if you will.
What would your suggestion be to implement this approach?
This looks good: http://blogs.msdn.com/b/jonathanswift/archive/2006/10/03/dynamically-calling-an-unmanaged-dll-from-.net-_2800_c_23002900_.aspx
If you don't know what all of your DLLs are ahead of time, you will probably need to call the Win32 function "LoadLibrary" "GetProcAddress" and "FreeLibrary." As far as I know, c# does not have a way to do a sort of Dynamic PInvoke automatically. See this blog post for more info
Alternatively, you could create a C# wrapper for each of your DLLs using PInvoke and then use managed delegates to call the functions. Then, by changing the delegate, you can call a different function (presumably in a different DLL) at runtime. This would depend on you having a complete list of the DLLs you intend to use at compile time. It is quite a bit more robust than the first option though. It's also a thousand times easier to let the runtime handle all of the marshaling for you. See this MSDN article for more information.
If they are already in C++, I would opt to write the managed assembly in C++.
This walkthrough could be a starting point. Especially the C++ guy does not need to learn C#.P/Invoke is a little bit slower, but the deeper issue is for you the version management as P/Invoke will lead to runtime-exceptions and not compile errors in case of changes.
You could use extern and DLLImport like facilities provided by Microsoft, For more details Go here or Here
Thus far I've figured out out I needed to recompile the library as a .dll instead of a .lib, enable /clr and /EHa instead of /EHsc. Now I've got a managed dll which I've added as a reference in my C# project.
Now how do I use it?
I'm prepared to write some wrappers, but I don't know where to begin or how to "see" what functions I've gained access to. I've read a little bit about how the class names and functions might be mangled by the compiler... do I need to go back and add __declspec exports everywhere (if so, how?), or is there an option in VS2010 that says "don't mangle it!"?
The C++ library in question is still under active development, so I'm hoping I can modify the C++ library as little as possible and just recompile it periodically with a few switches, and then expose the new functionality as I need it.
If you are going to compile your C++ (if originally was unmanaged C++) you will need to do much more than just add the /clr switch. In order for C# to use the DLL you will need to create managed classes and other types based on CTS which are compatible with C# (.NET).
See and ref classes.
A good book to read about the subject (IMHO) is this one
You can either expose the functions as C style functions (i.e., no mangling) from your dll or you can expose them as COM objects.
I'd suggest writing a COM wrapper, and using that instead. Have a look at http://msdn.microsoft.com/en-us/library/035x3kbh%28v=VS.80%29.aspx for intro instructions. You'll want to make your object interfaces derived from IDispatch and be automation compatible, which should enable the runtime to consume them without any custom marshaling.
A nice benefit of this approach is you can continue to build your native code as a library, and just make your COM project use it. Also, it's still native code inside the COM object, so there's much less potential for unknown problems (once you get the interface layer working).
That's my suggestion, anyway.
Yes, wrap it in à COM object. I believe ATL is what you meed to do this with the least effort.
I've got a code snippet of c# that I've been trying to translate into vc++, but I'm having some difficulties. So, I'm wondering if it is possible or advisable to mix c# and vc++; that is to say, can I call my c# function from vc++ and vice-versa. If so, are there tricks to it? If, not, why?
Calling C++ code from C# is easy enough and you should be able to find plenty of articles on Pinvoke and other types of interop.
For calling your C# code from C++ - if your C++ app is managed then you should be able to directly reference the C# assembly from your C++ app and use it as normal.
If ypu C++ code is not managed then you will need to use some sort of interop to allow your C++ assembly to call C# code, the only way of doing this that springs to mind is COM.
Try some of these links for more information on COM interop with C#:
http://www.codeproject.com/KB/COM/COM_DOTNET_INTEROP.aspx
http://www.codeproject.com/KB/COM/nettocom.aspx?df=100&forumid=14076&exp=0&select=864859
Is the VC++ app managed? If so, you could create a C# DLL, use it from your c++ app, and if you so desire, ILMerge them into a single EXE.
If you want to mix the two, I'd start with C# as the base project and then register an unmanaged (C++) DLL in your C# project. That way you can combine the reliability of the managed C# parent application with the speed benefits of C++ in any processor-intensive methods you might have.
I have a DLL made in C#, this DLL contains some clases like Creator.
I need to load this DLL and use Creator class in C++ unmanaged,
so Is there some way to create that instance or must I load just the functions exposed?
I need something like this:
CreatorInstance->Init();
Is this posible?
Most of what you need can be found here: http://msdn.microsoft.com/en-us/library/x0w2664k%28VS.80%29.aspx
Primarily, you need to learn about the /clr switch for C++ compilation. Then you need to understand the C++ extensions that Microsoft added to allow for mixed assemblies. (A C++ "pointer" to a managed class would use p^ instead of p*, and so on.)
John Fisher's approach using C++/CLI is by far the easiest means of handling this, but it is not the only means.
The other three options are:
1) Use COM interop to wrap the .NET class via COM
2) You can host the CLR in your native, unmanaged application, and call into it. For details, see this article.
3) You can host the Mono runtime, and use it to call your managed code. For details on this, see this page.
Option 2 and 3 are very similar, but IMO, 3 is easier than 2.
Here is an interesting article on how you should be able to accomplish this without using the /CLR option
http://www.codeproject.com/KB/cs/ManagedCOM.aspx
Works pretty well.
First of all, it is possible and you do not "have" to use CLI or the /clr switch. Using the good old COM architecture you can do it pretty easily http://msdn.microsoft.com/en-us/library/zsfww439.aspx. Understanding the way COM works might be the biggest challenge here, but it's usefull once you know it.
Is it possible to use a C++ .lib file from within a C# program?
There are plenty of ways. Read about "interop" in MSDN..
One way is to expose the lib as a DLL, and then use pinvoke to call these functions from a C# project. That limits you to a C-style interface, though.
If your interface is more complex (e.g. object oriented) you can create a C++/CLI layer that will expose the lib's class structure to your C# program. This means you'll have to create a managed C++ (or C++/CLI as it's now called) project; then design an interface in managed code that will be implemented by calls to native C++ (i.e. your lib).
Another way of doing this is by wrapping your lib with a COM interface. But COM's a pain, so I wouldn't...
Not directly. You can create a C++/CLI assembly that consumes the lib and then access that from C#, or you can wrap the lib as a DLL.
What you need is a managed wrapper (C++/CLI) around the native C/C++ library that you are working with.
If you are looking for any C++/CLI book I'd recommend Nishant Sivakumar's C++/CLI in Action
Already answered to wrap it but here's an example . Good luck!
I would take a look at swig, we use this to good effect on our project to expose our C++ API to other language platforms.
It's a well maintained project that effectively builds a thin wrapper around your C++ library that can allow languages such as C# to communicate directly with your native code - saving you the trouble of having to implement (and debug) glue code.
No. You can only use a full .dll from a C# program.
That depends, do you have any limitations on this scenario?
If you have a lib file, it should be possible to first compile it into a DLL file, secondly exposing the functions you want to call in the DLL interface, and thirdly, call them using C# native methods (have a look at pinvoke.net on how to do this bit).
you can't use a lib, but like the others said, you can use it if you wrap it into a dll.
swig can take the headers of your .lib, and if they are not too complex it can generate the dll for you which you would then call with a pinvoke from c# which would also be generated by swig.
if your library is complex and has reference counted smart pointers everywhere, you should find an alternative.