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.
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.
Is C++ source code required to build a .NET wrapper or static libraries *.lib files are just enough?
We plan to use SWIG.
Thanks.
w.r.t. your question asking specifically about static-libraries *.lib:
Is C++ source code required to build a .NET wrapper or static libraries *.lib files are just enough?
I doubt you actually intend to wrap a static-lib: Statically-linked libraries generally aren't redistributable nor portable (e.g. the authors of closed-source static libraries need to build them every time a new supported compiler comes out, e.g. you can't use a GCC lib with VisualC++ 2017, and an x64 VisualC++ 2017 lib won't be compatible with an x86 VisualC++ 2015 project) - and even if you loaded a *.lib into your process' memory and jumped into a known function address inside the lib's image, it would immediately break because the static library's code will have references to certain memory addresses (e.g. of string-constants) which aren't yet relocated - you'll get an segfault (or "Access violation" on Windows) crash if you're lucky (if not, it'll definitely corrupt your process' memory space before being detected).
P/Invoke in .NET Framework and .NET on Windows (i.e. using [DllImport]) only supports DLLs (Dynamically Linked Libraries), not statically-linked libraries.
You can also call into native code if the native code is available as a COM object, or can be accessed through platform features like OLE, WMIC, ADSI, etc (assuming your code's process is the same ISA as the native code you want to call, as it will still be loaded into your process, which is why you can't use 64-bit Office Excel to open databases where only a 32-bit OLE-DB or ODBC driver is available).
When a library is available as a *.lib then you need to make your own native host first - a simple C/C++ Win32 (PE) EXE or DLL that re-exports all of the useful functions from that *.lib will be sufficient - because then those exports can be imported by C#/.NET.
But in general:
If you are exporting COM objects to .NET then you don't need both the source-code files (*.c, *.cpp) or header files (*.h and *.hpp), only the IDL files or *.tlb (Type-lib) which the compiler will generate for you.
If your native code is also available through other platform features like OLE, ActiveX, COM Automation (IDispatch), ODBC, OLE-DB, ADSI, WMI, etc then you wouldn't be using [DllImport], and those platforms all either provide a standard interface (like ODBC and OLE-DB)
But generally speaking, no - you do not need the source-code (i.e. both *.c and *.h files) to create a .NET wrapper around native code exported from a native DLL and imported into .NET using [DllImport].
But you will need the header files (*.h) from a C/C++ project in addition to knowing the compiler settings (for finding out things like calling-convention, parameter marshaling info, etc) and a PE inspector (to verify the exported functions are at least present in the DLL you want to load).
Don't forget to ensure you provide both x86 and x64 native DLLs for all functionality if you're compiling your C#/.NET code for AnyCPU (tip: Using a 32bit or 64bit dll in C# DllImport )
I need to integrate this C# dll
in my C++ code. I want to call some functions written in C# from dll and the rest of code write in C++. What is the easiest and quickest way to do it? The program will be executed only on Windows.
There are basically two cases to call a .NET DLL from unmanaged code:
The .NET DLL exposes a COM interface. In this case, you can use COM from your C++ code.
The .NET DLL does not expose a COM interface. In this case, you have two possibilities (to make it simple):
2.a. host the CLR as described here: Loading the Common Language Runtime into a Process
2.b. write a piece of managed C++ code (another DLL - written in C++/CLI) to wrap the .NET DLL and expose 'old way' DLL exports to unmanaged clients.
I don't specifically know the sharpbox system, but it looks like it's pure .NET and does not expose COM interfaces, so 2.b might be the best way to do it (not so easy...). Maybe it has a REST/Web easier API you could use.
PS: you can also add exports to a .NET DLL. This is described here: Is is possible to export functions from a C# DLL like in VS C++? but it's kinda hacky.
End Goal
I have an x86 dll built in c++. I need to be able to use the dll from a portable class library. This can be directly or indirectly, but I want to keep the entire application local on the users computer.
What I have tried
I have designed a c++/cli wrapper to allow access to the dll. I confirmed it works through an x86 console C# project.
I tried using the wrapper directly from a portable class library but it would not allow the reference.
I tried using the wrapper from a wcf library but the library is having problems with the cross platform dll.
I think I'm making this way too complicated but I am unfamiliar with a way to do what I want. I can't rebuild the dll in 64-bit and do side by side loading - I only have the option of using the x86 dll.
Thank you for the help.
Why do you need to reference a C++ DLL from a Portable Class Library? A C++ DLL isn't going to be usable from multiple platforms. The point of PCLs is that they can run on more than one platform, but that means everything they reference needs to also be a PCL.
Probably what I'd recommend is to use the abstraction pattern, as described here.
I am developing a managed lib (using Microsoft Web Services) and I am
including it into a c++ project. The project doesn't use /clr option,
so when I include my library's header file VS2005 show me an error
saying I have to use /clr option. Doing this I have a incompatibility
with /EHs command line option (error D8016), but changing from EHs to
no exception handling not solving problem and keep showing me same error .
Any suggestion is welcome.
Thank you in advance.
If you have unmanaged C++ code and want to use managed code, you have a few options:
Change your unmanaged code to C++/CLI, by use of the /clr switch.
Write a C++/CLI wrapper library. It could DLL-export unmanaged functions which you call in your unmanaged code.
Skip the wrapper library and directly DLL-export unmanaged functions via this library.
You can't use a managed lib from an unmanaged c++ application. Since you add the /clr option, your c++ application becomes managed too (just for the record :) )
Here's what might help you: http://msdn.microsoft.com/en-us/library/ffkc918h.aspx - the restrictions of the /clr option.
It is possible to write managed c++ adapter, that will call the C# library, and call this adapter from unmanaged c++ program as you would usually call a normal c++ library. You will compile your adapter library with /clr and your main c++ program without /clr if for whatever reason you want to keep it unmanaged.
You can embed a mono environment and start an AppDomain. mono's runtime API will allow you to instantiate classes and call members on them. It will be clumsy, but is will work
http://www.mono-project.com/Embedding_Mono
Note that Mono is a full .Net 4.0 compliant CLR and it can work with the Microsoft core libraries on Windows.
On windows and Unix it can work with the Mono corlib/class libraries. There are areas not covered in Mono, but they seem to get sparse. You can use the MoMa tool to spot whether your application uses incompatible/incomplete APIs.
Or you can just use the Microsoft .NET framework, assuming you're on windows anyway!