I am trying to use the marshalling library in my C++/CLI project. When compiled with #include <msclr/marshal.h> I get the error error C2872: 'IServiceProvider' : ambiguous symbol. Most of the resolutions seems to be suggesting moving #include <windows.h>
like the one here -> Ambiguous references, but I dont have those includes. All I have is:
using namespace System;
using namespace System::Configuration;
using namespace std;
#include <msclr/marshal.h>
How do I debug this issue ?
You do, indirectly, marshal.h includes it. It dumps an enormous amount of identifiers in the global namespace. The macros are especially awkward, lots of them match names used in the framework.
Lots of things that marshal.h does can be done by the Marshal class as well. But I can't help you with that, you didn't mention why you want to use it. You can solve this particular mishap by putting the #include directive before the using statements:
#include <msclr/marshal.h>
using namespace System;
using namespace System::Configuration;
Make sure you only have the:
using namespace System;
in the cpp file of the CLR project and not in the header.
Visual studio automatically adds it to the header when creating a CLR class library project.
In the cpp itself, the includes must precede the "using namespace".
Related
I am creating a C++/CLI wrapper for native C code that has it's own Object typedef and am receiving the C2872 'Object': ambiguous symbol error when linking. The compiler output is:
1>C:\src\OS_kernel.h(27): error C2872: 'Object': ambiguous symbol
1>C:\src\OS_types.h(261): note: could be 'ObjectStruct *Object'
1>C:\src\OS_kernel.h(27): note: or 'System::Object'
It may be worth mentioning that I am mocking this native C code for the purposes of the C++/CLI wrapper; not sure if that opens up a potential solution that would otherwise not be available if no source code was available. I'm guessing there is a way to specify which definition I want the code to use, but I don't know how to specify that. Is that possible? I want to specify it to use the ObjectStruct *Object.
It would be great if I didn't have to modify the mock code since it could potentially be hundreds or thousands of individual places.
As an aside, I am also receiving this error for other types the native library is using, such as Buffer and Boolean.
OK, since you're getting the error in OS_kernel.h, I'm guessing that's part of the C code you're wrapping.
Obviously, one possible solution is to treat the name Object as a reserved word, and edit your C code to not use it. One could argue that this is the most correct solution, but it may not be possible to do that.
Depending on how you're referencing the C code, it may be reasonable to compile it as C++, and stick it entirely within a namespace. That way, when the C code (now C++ code) uses Object it will see the typedef within its namespace, and you'll have the option to reference either namespace in your code.
The fact that you're getting this error from your library's header file indicates to me that you've got a using namespace System; directive, and that the #include of your library's header files comes after that using directive. Consider removing the using namespace System;, or at least moving it after the #include. This way, you won't get that error in the library's headers, you'll just have to deal with it in your code.
I am trying to call functions in c++ from C# and to do this, I created a C++/CLI project to wrap C++ codes.
My code compiles, but during linkage, I am getting error that linker can not find methods which are defined in c++ code.
The c++ code is a static library and I add a reference to it in C++/CLI project (common properties -> framework and references -> add new reference)
My questions:
Is there anything else should I do?
is adding reference in this sections means that the reference is a .net assembly? Or could it be a reference to a static library.
Edit 1
I am sing VS 2012 on windows 7 64bit
Linker Error:
Error 3 error LNK2019: unresolved external symbol "public: static class MyFile __cdecl MyFile::ReadMyFile(char *)" (?ReadMyFile#MyFile##$$FSA?AV1#PAD#Z) referenced in function "public: static class MyFileWrapper::MyFileWrapper ^ __clrcall MyFileWrapper::MyFileWrapper::ReadMyFile(class System::String ^)" (?ReadMyFile#MyFileWrapper#1#$$FSMP$AAV11#P$AAVString#System###Z) MyFileWrapper.obj
You didn't post the linker error message, that makes it difficult to answer this question accurately. The most common causes:
Forgetting to tell the compiler that the function is a native function and not a managed one. You can tell from the linker error message when you see it using the __clrcall calling convention, native code normally uses the __cdecl calling convention. You fix that by putting #pragma managed(push, off) before the #include, #pragma managed(pop) after it.
Trying to link a static library that was compiled with /clr in effect. That's not supported without otherwise drawing a complaint about that when you build the library, unfortunately. The equivalent is already well supported by the CLR, it binds libraries at runtime. You fix that by creating a class library project instead so you'll get a DLL after building it. Use Add Reference to import the declarations from that assembly instead of using #include.
Forgetting to tell the linker that it needs to link an unmanaged static library or import library. Using Add Reference is supported in VS2010 and up, on earlier versions of VS you need to use the Linker, Input, Additional Dependencies setting or use #pragma comment(lib, "name") in your source code.
$$F part of the given mangled name is a marker of function modifier , that means managed function [Managed C++ or C++/CLI], according to "Visual C++ name mangling".
I faced very similar problem. I figured out that in my case there was:
<ProjectReference Include="ProjName\ProjName.vcxproj">
<ProjectReference Include="..\ProjName\ProjName.vcxproj">
I've just fixed that and made rebuild and it helped me.
I have a C++ project (visual studio 2010) which consists of native code and c++/cli code as well. I cant compile the whole project with /clr, so I just do it for the respective c++/cli files. My Problem is that a header file cant be compiled with /clr, but I want to make some c++/cli functions reusable within the whole project and therefor define the method prototypes in a header file to include it in every file where I need it. Is there a solution? I have tried to define some mixed code method prototypes in a header file, but /clr must be switched on for that to compile.
Here is my example:
Test.h
#include <Windows.h>
#include <vector>
#include <string>
using std::vector;
using std::string;
#include <msclr/marshal.h>
#pragma managed
using namespace msclr::interop;
using namespace System;
using namespace System::IO;
using namespace System::Runtime::InteropServices;
public ref class Test
{
public:
int Foo();
};
Test.cpp
#include "Test.h"
int Test::Foo()
{
return 4;
}
Intellisense is complaining with errors in Test.h like c++/cli must be enabled to use #using. But I think this is negligible and it would compile anyway.
Compilation aborts with a Linker Error (sry, i have german VS version)
Fehler 6 error LNK1255: Fehler bei Verknüpfung aufgrund von Metadatenfehlern.
Fehler 4 error LNK2022: Fehler bei Metadatenoperation (8013118D) : Duplizierte Typen (_PROPSHEETPAGEA) wurden gefunden, aber die Typenlayoutinformationen sind nicht konsistent: (0x02000198).
Fehler 5 error LNK2022: Fehler bei Metadatenoperation (8013118D) : Duplizierte Typen (_PROPSHEETPAGEW) wurden gefunden, aber die Typenlayoutinformationen sind nicht konsistent: (0x020001d1).
I definitely dont have a duplicate class "Test" elsewhere, so I dont know where the duplicate comes from. What are typelayout informations and why are they not consistent?
I think you've all missed the point.
You can easily compile a native project with some /clr classes. (For example: A native DLL will still function like a native DLL, however, it can also be loaded into C#, and it's /clr compiled classes can then be accessed in C#.)
That's why such an option exist at the file level. (Right click .cpp: Properties->C\C++->Common Language Runtime Support- /clr)
The problem is:
Communicating between native\managed classes, since .H files cannot be set to use /clr, those cannot be used to reference a managed class elsewhere including other /clr files within the same project. (ie, you can create /clr files, but, they can't talk to each other, nor can you reference them within native portions of the project.)
The best solution I can find is to create a "glue" C# .dll file.
Create a new C# class library, add the Native DLL as a reference, then compile.
Now, in your native project, you can load the C# DLL, and access the natives /clr stuff through it. (The managed code you reference this way can be used with native\managed code.)
It's very possible, but, I cannot find a straightforward way to accomplish this.
That's what the topic is about, there seems to be no way to reference /clr classes due to header files not working when you set /clr at the file level. (ie, a header cannot contain /clr code unless the WHOLE project is set to /clr.)
There must be a way to reference /clr stuff without headers, or C++\CLI is just broken, I can easily load native code into /clr files by using pragma + headers, however, the reverse is looking impossible short of my "glue" solution.
That is what I believe this topic is about.
My method works, but, it's very tricky to get right, and compilation is a pain due to circular dependencies, etc,.
I really hope there is a proper way to do this, I've been looking, and my search led me here...
The real solution, would be to make .h files support /clr, then you could define your managed class in the header, and be able to freely reference it using standard methods, like include\using\pragma, etc,.
Perhaps you're looking for
#if __cplusplus_cli
Documented here on MSDN
I am working on a project that requires a third party library implemented in C++. I have successfully added library to my xcode project, but the problem is that the classes in library contains namespaces and when I try to access methods via namespaces, the XCode generates an error that: "utils undeclared". "utils" is the namespace I am trying to use.
My question is that is there a way to use C++ namespaces in ObjectiveC?
The code I am using to call the method is:
utils::method();
I have tried renaming my ObjectiveC ".m" file to ".mm" file, but the problem remains the same.
We are using C++ libraries in Objective-C and have no problem using C++ namespaces. As Mustafa has indicated, you need to change the Objective-C file extension to .mm to get XCode to recognize the file as Objective-C++. Then you just need to #include (not #import) the C++ headers containing the C++ namespace declarations - this is as you would normally do for 'normal' C++.
I recently started writing a C++/CLI wrapper for a native c++ library. I'm now getting this compile warning
"warning LNK4249: directive '/CLRTHREADATTRIBUTE:STA' conflicts with command line; ignored"
My c++/cli wrapper is set up for MTA in the linker's command line arguments, but I have no idea what file or project is trying to give the STA directive.
I did enough reading to get worried about .NET forcing libraries to become multi-threaded. I've read that this mostly affects my application's use of COM, but I am not really sure if or where my DLL uses COM. I use the interop services to marshal string data and am using 'msclr\auto_gcroot.h' to point to managed classes from unmanaged ones. In the native c++ library that is being wrapped, I include the following headers:
#include <afxwin.h> // MFC core and standard components
#include <afxext.h> // MFC extensions
#include <afxmt.h>
#include "Winsock2.h."
#include <time.h>
Does anybody have any advice that could help me avoid painful experiences in the future, or should I just not worry about it?
So far so good. I haven't seen any real problems with this; I think it is just because MFC is a single threaded library, so it wants to compile that way. So, for my case, I think as long as I treat all MFC objects and such as not thread-safe I'll be okay.