The problem is - I want to write a template class in C++, put it in a DLL, and then call it from my C# project. Is it possible? Can you please provide any references or articles on about how to do it?
EDIT
I want DLL to be written in unmanaged C++
Template class could not be exported. It does not exist until someone instantiate it. You should explicitly instantiate it and then export it as usual class.
I think this question may help you out:
Use C++ CLI template class in C#
By using C++/CLI you can expose your C++ classes as .NET classes where they use compatible features. You won't, however, be able to expose your template definition, but may be able to use a concrete class that specializes that template.
When you build a C++/CLI class you can reference it just like any other .NET assembly.
You create it just as with any other DLLs - the main idea behind DLLs is that it can be created in any programming language, and be used with every other. Just remember that C++ is unmanaged, so it has to be treated carefully. Look for instance here (MSDN forum).
One more link.
In general, use DllImport decorator to import functions from DLL file you've created in C++. Example from MSDN:
using System.Runtime.InteropServices; // DllImport
public class Win32 {
[DllImport("User32.Dll")]
public static extern void SetWindowText(int h, String s);
}
As far as I recall there's a bit of a problem.
It is possible to Have C# use a C++ Dll (managed and unmanaged)
It is possible to have unmanaged C++ use a C# Dll (you need to do this via COM and an interface).
I'll see if I can find more detailed information
Related
I am working on a project. In that C++ code is referencing to a Class Library which is written in C#. I want to pass Object of C++ Classes to C# Class library.
So Is this possible, If yes please let me know how ?? otherwise I will have to pass around 100 arguments to C# Class Library.
Regards,
Vivek
you shoul use marshling.
Marshaling is the process of creating a bridge between managed code and unmanaged code; it is the homer that carries messages from the managed to the unmanaged environment and reverse. It is one of the core services offered by the CLR (Common Language Runtime.)
namespace System.Runtime.InteropServices.Marshal
Read here a good blog about marshling
If you have this option, you can add a cpp file to your project that will be compiled with enabled CLR (managed C++). From managed C++ you can call C# classes. You can find and example here:
Managed C++ to form a bridge between c# and C++
Another option is to create a managed C++ dll as a bridge between C++ and .NET if you don't want to enable CLR in your calling native application. I used this trick and it worked fine but be aware that once you load that bridge dll library, CLR is loaded in memory and your process gets "infected" by CLR. You will have that effect anyway though.
I would like to use a set of unmanaged C++ libraries for a large project in my C# .net application. After downloading the code for the libraries, I noticed that the demo project that uses the libraries was actually done in C++/CLI.
Since the demo project was done in C++/CLI the author wen't ahead and added most of the type definitions and interface definitions in header files in the external dependencies folder of this demo application.
If I can, how exactly can I use these definitions to interop with these managed C++ dlls?
To recap:
Libraries are written in unmanaged C++
Demo project is written in managed C++ has type definitions and interface definitions created to use the unamanged C++ dlls, they are located in the "External Dependencies" folder and are header files(.h).
I want to use these unmanaged C++ dlls in my C# project, can I somehow use the definitions to interop with them?
4.If not, what would be my best option to interop with them? COM interop?
I think you are looking for this....
This is an example from the FMod DLL wrapper for c#
[DllImport (VERSION.dll)]
private static extern RESULT FMOD_DSPConnection_GetInput (IntPtr dspconnection, ref IntPtr input);
I know it is a lot of work but way better than rewriting the unmanaged DLL.
Not knowing which library you intend to use I can only hope this helps
I have the c++ source code of functionality which is appealing to me.
What effort/work is involved/required in order to either reference this from a .net application or build this code as a .net assembly (preferably c#)?
This is my first attempt at porting code, so please breakdown your answer for me step by step.
There are several ways of doing it.
PInvoke
Create C++/CLI wrapper around your C++ native code (make static library out of C++ native code) and C++/CLI generated assembly can be easily utilized in .net application.
COM, i.e using interop (which is difficult among all the options)
In my suggestion easiest way is to use option 2, but you need to take care of proper marshaling.
Solution A:
If you have the source code, then compile the CPP program as a DLL file.
Use P/Invoke
Solution B (if the functionality you want is in a static library):
Create a stub function caller and compile THAT as a DLL
Same as solution A.2
I have C++ code that is written with the Qt library.
I compile it with \clr and when I add a 'DLL' file to C# reference, I have no class and namespace that declare in it 'dll'.
Where is problem?
I don't know if you resolve your problem.
You need to make a C++/CLI class in order to use it in your C# code. In the code of this class you can make unmanaged calls but you need to return managed type. You can find information about C++/CLI and managed/unmanaged context on msdn.
How would I export functions defined in a C# class library, while enabling them to be imported to and called from an unmanaged C++ application/DLL ?
Strictly speaking, you can't just export functions as you would in a classic .dll, as .NET .dll's aren't really .dll's at all. Your only three options are:
Use managed C++
Expose your C# classes as COM objects and consume them from your C++ code
Host the .NET runtime in your C++ project and interact with your C# classes through that.
Your C++ Apllication would have to start by hosting the CLR. There is nothing special required from the .NET DLL.
You would not. Not supported. You can pretty much only export COM objects from a C# class librarly.
You could also make a C++ wrapper for your C# library - a simple Managed C++ DLL that would import .NET methods and export them natively. This adds an additional layer, but it might be useful if C# library is a must have.
Another option is to tweak the compiled assembly to export the functions. A C# compiler cannot do this, but it takes a slight change of MSIL code to get the things done.
Have a look at this article - there're some links on how the stuff works, and a tool to automate it (though I haven't tried it myself).