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.
Related
I'm noob in C# and I already searched on the web. Anyway I'm still not sure about this and I do not have the total control of the code I have to implement, this is why I would like to be sure I needn't make any dll. I have a C++ file with a method, and I want to call this method from C# code. I just added "extern C" to the function.
When I just add the .h and .cpp files to the C# project they aren't detected. And of course, when I try to add it as reference, it doesn't work.
So do I absolutly have to make a dll ?
Your options for accessing the C++ code from C#:
Compile C++ as unmanaged DLL and access using p/invoke. This requires the C++ code be exposed using a C style API.
Compile C++ as unmanaged DLL and access using COM. This requires that you wrap your C++ in as COM objects.
Compile C++ as mixed/mode C++/CLI assembly and access the assembly as a managed reference. This requires that you wrap the original C++ as managed C++ ref classes.
All of these options, by necessity, involve the creation of another module/assembly. You cannot link the C++ code directly into your C# assembly.
You might like to try using the PInvoke Interop Assistant to generate the C# necessary to interact with the DLL via Platform Invoke. Be aware that this is imperfect though so YMMV.
Another alternative, if you have the knowledge and patience, is to make a COM component out of your native C++ DLL and consume that from C# by using the Type Library Importer to create a managed wrapper.
You won't be able to interact with .cpp/.h files since you need at least a binary object (assembly) for C# to interact with and C# won't generate any binaries from .cpp/.h. That's on the subject about adding these files as references to the project.
As for the argument that you don't have control over the code - well, don't make a DLL out of the actual .cpp/.h, but make your own thin DLL that has a wrapper object that just includes the headers, calls whatever method you would be calling and links to the appropriate .o files or .lib or whatever you have. If the interface changes you would just changed your thing wrapper which should be easy.
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 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 been looking for a way to call a function written in a C# EXE project (VS 2008) from a C++ DLL project. I can include the C# code as part of the C++ project itself if that is possible. All that I have been able to find is calling the C# DLL from C++.
Ultimately I want to call C# code from VB6 but I ask the question this way because I don't believe the later way is possible without an intermediate step.
Thanks,
Ian
Ultimately I want to call C# code from VB6 but I ask the question this way because I don't believe the later way is possible without an intermediate step.
You can register the C# classes to be visible to COM, and then call them directly from C++ or VB6.
For details, see the Example COM Class on MSDN, as well as Interoperability.
You can compile your c++ project with the /CLR option and then call C# from within it. To do that you need to include vcclr.h and then add a using statement for each dll you need to call from.
#include <vcclr.h>
#using <System.dll>
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