Using VS2010, I am working on wrapping a large number of .h files and one .lib from native C++ (using MFC) to C++/CLI for eventual use as a referenced .dll in C#.
While creating the wrapper I'm getting compiler errors stating CObject is undefined. In the project properties I have set use of MFC to use MFC in a static library and runtime library to multi-threaded debug DLL (/MDd). I am linking the .lib and including the .h files. The compiler errors are in the .h files where some of the classes are inheriting from CObject.
Shouldn't the compiler know about CObject?
Are you #including the MFC headers? afx.h, afxwin.h, anything like that? It's possible that #include was in stdafx.h in your native C++ project, and didn't get copied into the header files that you're using in your C++/CLI project.
Related
I have a c++ project compiled with /clr support(e.g. wrapper.dll). This project(wrapper.dll) is a wrapper between .Net enviroment and unmaged dll(e.g. noCode.dll), which inherits from. I dont have access to code of inherited dll(noCode.dll), but I can link it to my wraper (by noCode.lib and noCode.h files).
When I want to use my wraper(wrapper.dll) in c# project I reference it and have to copy my unmanaged dll(noCode.dll) to location of c# project execution.
Is it possible to merge c++ unmamaged dll(noCode.dll) to managed dll(wrapper.dll) to allow to use only one file by reference(noCodeWrapper.dll) in c# projects?
It is not possible to link DLL files together.
But you can add that nocode.LIB to your DLL and then you don't need [DllImport]. Since you have LIB and H files, you can call the "nocode" functions directly from your managed C++ code.
If you had access to noCode.dll source code you could integrate it with wrapper.dll. Otherwise merging DLL binaries is not a task that could give predictable results.
I am trying to run un-managed native C++ class code from C# by writing a wrapper. My C++ code compiles as a static library (.lib) with no problems. The code depends on other code which, I believe, are all compiled as static libraries. I am not able to compile this as a DLL as there are linker errors.
I have just learnt that the wrapper needs to be compiled as a DLL so that it may be invoked from C#. Is this true? Can I not compile my wrapper as a static library to be used in C#?
C# cannot load .lib files.
P/Invoke can only load .DLL files (they don't have to be named .DLL but they have to be the right file format).
I want to create a dll in visual c#, and use it in win32 program (visual c++).
From what I understand, for adding dll file in Visual C++ , I need also .h file and .lib file, but when I create a class library in visual c# I only get dll file.
Is it possible to create a .h file and .lib file in visual c# ?
No, it's not possible. But here is what you can do to use a C# library in C++:
C++/CLI Wrapper (this allows you to have both managed and unmanaged code in the same source file. The managed portion can then call the C# code). Here you can find an example.
Host CLR (the CLR acts as a library that can be loaded and "hosted" by a process).
COM Interop (expose your .NET type as a COM interface and matching coclass which you can easily use from unmanaged C++).
This thread is also quite interesting!
You could use LoadLibrary and GetProcAddress to load the DLL dynamically and you wouldn't need to create the files you refer to. You can read more here.
Has any one compiled lib x264 using CLI backend for gcc compiler? (Compiled x264 into .net dll)
Are you using C99 features? If not, Visual C++ with the /clr:pure option should do the trick. You will need a little bit of C++/CLI mixed in to define your entrypoints that other .NET projects can call, but those can be in completely separate files (you can share entire C-only source files with native projects).
EDIT: Basic guide to making this work:
In Visual Studio, create a C++/CLI Class Library project
Add all your C source files to the project
In Project Configuration, set the include path so your headers are found
In Project Configuration, also set "Use of Common Language Runtime" to /clr:pure
In the .cpp file created by the new project wizard, add #include directive for the header files which prototype the functions you want to use.
In the ref class created by the new project wizard (in the aforementioned .cpp file), add some functions (maybe static functions) which call your C library functions.
Compile, add this .DLL as a reference of your C# project, and enjoy
As a hint, instead of creating a forwarding function in the ref class for every function in the library, you may want to make functions that do useful work (for the particular definition of useful for your particular project) by calling a bunch of library functions.
You'll probably want to get comfortable with the marshal_as template which is good for converting .NET System::String into C strings and back again.
I am wrote a visual c++ win32 console app, and i wrote it and tested it in
win32 console project
. then i switch to
win32 project
and imported all the source files and created a dll for it. by mark the class i want to export as
#define DllExport __declspec( dllexport )
class DllExport theClass {
}
it works and the dll is generated. then i created a another c# project and want to add the dll to the project. by reference->add reference-> browser. then i select that dll.
then it is gives me an error
a reference to the '''''''.dll could
not be added. please make sure that
the file is accessible, and that is a
valid assembly or com component.
anyone knows where i did wrong to generate/import the dll?
thanks
The Add Reference dialog can only work for DLLs that contain metadata (managed code) or a type library (a COM server). Your DLL doesn't fit that bill, you can only use the [DllImport] attribute in C# code to use the P/Invoke marshaller to call an unmanaged DLL entrypoint.
That can not be a native C++ class, like you are trying to do, there is no reliable mechanism for managed code to allocate unmanaged memory and call the constructor (and destructor) of a native C++ class. Short from the difficulty of finding the constructor and destructor code, there is no way for the P/Invoke marshaller to know the size of the object. The C++ language doesn't generate the metadata necessary to know this required information.
If you want to pursue P/Invoke then write an plain global function, decorated with extern "C", __declspec(dllexport) and (optionally) __stdcall.
If you want to export a C++ class then the only avenue is using the C++/CLI language and write a "ref class" wrapper for the native C++ class.
Or you could write a COM coclass, the universal glue in Windows. Very well supported by .NET, probably not something you want to pursue if you never wrote COM code before. ATL is the best way to get one going.