In VS C/C++ you could use extern "C" __declspec(dllexport) -function declaration-.
How do I accomplish this in a C# dll? Is there C# code equivalent to the above code?
Edit: More info
I am trying to create an add in for Notepad++ and I want to use C#, but the common way I've seen so far is to use legacy C++ code with the above call to export a few of the functions that Notepad++ expects to import and call. There is an example app using C#, but this still requires a loader DLL, which I assume from the comments/answers below is the only way for C#.
Unmanaged Exports =>
https://sites.google.com/site/robertgiesecke/Home/uploads/unmanagedexports
DLLExport => https://github.com/3F/DllExport
How does it work?
Create a new classlibrary or proceed with an existing one.
Then add the UnmanagedExports Nuget package.
This is pretty much all setup that is required.
Now you can write any kind of static method, decorate it with [DllExport] and use it from native code.
It works just like DllImport, so you can customize the marshalling of parameters/result with MarshalAsAttribute.
During compilation, my task will modify the IL to add the required exports...
I've seen people do this before, but it required ildasm, adding the MSIL .export directive, and then reassembling. A program named dll_tool can do these steps for you.
If you want to build a mixed-mode DLL with both native and managed exports, you should be using C++/CLI, which is specially designed for this purpose.
Yes, it is possible to export functions from a C# dll in much the same way that C++ does it! You need a little help from an add-in Unmanaged Exports (DllExport for .Net) that facilitates this process, or from a similar method such as Exporting functions in C#/VB.NET to native code.
Please see Code to Export C# DLL to Metatrader Build 600+ for a working example using Robert Giesecke's C# Project Template for Unmanaged Exports to export a C# dll to a legacy application (Metatrader) that has a great deal of similarity to C++.
Additionally, you might find Native and .NET Interopability interesting though it is mostly geared toward accessing native code from within .NET rather than the other way around.
No, you cannot do that in the same sense as you do in C and C++.
But you can create COM API to achieve that which then you can use in C and C++ code.
See these articles
C# Classes as COM Objects
Calling Managed .NET C# COM Objects from Unmanaged C++ Code
COM Interop Part 1: C# Client Tutorial
Related
I have a program written in C++ with a main function that calls a bunch of other C++ classes/functions.
I am new to C++ (been a python programmer), so I'm wondering - What are the steps I need to follow to be able to export this as a DLL that is importable from a C# program? Any suggestions?
If you want your C++ classes to be usable in a C# application you will need to use COM or target the CLR in your C++ program (i.e., use C++/CLI).
If you simply have some functions in the C++ DLL that you want to call from C# that take POD type arguments then declare each function as extern "C" to avoid name mangling and use the DLLImport attribute to import the function. PInvoke.net is a great resource here.
If you are only exporting plain functions, not classes, you can p/invoke them. if ypu really need the classes, you have to write your project as a C++/CLI and reference it in your c# project like any other .NET assembly.
Currently I have abc.dll which is fortran dll. Now I want to call C# code from abc.dll. Is there any way to call the C# code from fortran dll ?
thanks
Sagar
Typically, if your program is written entirely in native code (as I believe the Fortran dll would be), you'll need to call a method that's been exported (dllexport) from another native code module. In this case, you'll want to create a Managed C++ dll that exposes a native interface and internally makes the call into the C# code.
Edit: If the hosting program is managed code, and you need to do a C#->Fortran (native)->C# calling sequence, then delegates as unmanaged function pointers can be used as linked in the comments above. However, if the executable is not managed code, you'll need to go the route I mentioned.
Compilers supporting recent Fortran language features (the 2003 standard) will support C-interoperation. You interface with other code through its C interface, using the ISO_C_BINDING module and the BIND construct. Most recent compilers have it, it's standard and you can find a lot of documentation (like this one) by Google'ing the keyword ISO_C_BINDING.
Is it possible to call C++ code, possibly compiled as a code library file (.dll), from within a .NET language such as C#?
Specifically, C++ code such as the RakNet networking library.
One easy way to call into C++ is to create a wrapper assembly in C++/CLI. In C++/CLI you can call into unmanaged code as if you were writing native code, but you can call into C++/CLI code from C# as if it were written in C#. The language was basically designed with interop into existing libraries as its "killer app".
For example - compile this with the /clr switch
#include "NativeType.h"
public ref class ManagedType
{
NativeType* NativePtr;
public:
ManagedType() : NativePtr(new NativeType()) {}
~ManagedType() { delete NativePtr; }
void ManagedMethod()
{ NativePtr->NativeMethod(); }
};
Then in C#, add a reference to your ManagedType assembly, and use it like so:
ManagedType mt = new ManagedType();
mt.ManagedMethod();
Check out this blog post for a more explained example.
P/Invoke is a nice technology, and it works fairly well, except for issues in loading the target DLL file. We've found that the best way to do things is to create a static library of native functions and link that into a Managed C++ (or C++/CLI) project that depends upon it.
I'm not familiar with the library you mentioned, but in general there are a couple ways to do so:
P/Invoke to exported library functions
Adding a reference to the COM type library (in case you're dealing with COM objects).
Yes, it is called P/Invoke.
Here's a great resource site for using it with the Win32 API:
http://www.pinvoke.net/
Sure is. This article is a good example of something you can do to get started on this.
We do this from C# on our Windows Mobile devices using P/Invoke.
The technology used to do this is called P/Invoke; you can search for articles on the subject. Note that it is for calling C from C#, not C++ so much. So you'll need to wrap your C++ code in a C wrapper that your DLL exports.
Have you considered Apache Thrift?
http://thrift.apache.org/
It seems like a very very neat solution.
In my project I got a device which comes with C++ Sample codes. The codes are ok and the device is working as expected.
But I need it to talk with my C# interface because all other devices are currently using C# interface.
So I am planning to create a DLL Wrapper for the driver. I will create a C++ Library of my own (from source code with proper interface) and Call this C++ Library from C# using DLLImport (just call my interfaces there.).
I am pretty sure it can be done this way, but I have never created a C++ Library and used it from C# yet. So, can anyone refer me to some tutorial that goes with my problem?
I am using C++/C# int VS.NET 2008.
Regards,
Maksud
Have a look at
using a class defined in a c++ dll in c# code
Another useful tool you have at your disposal is C++ CLI.
You can use C++ CLI to create an intermediate library - one that exposes managed classes but runs unmanaged C++ code. You can actually mix managed and unmanaged C++ in the same DLL.
The unmanaged portion can accesses the unmanaged DLLs without having to use the PInvoke functions.
Your C# code can access the managed classes in this intermediate library.
Depending on the DLL and what you need to do you may not need to create a wrapper directly. You might be able to get away with P/Invoke for the functions. You will need to evaluate your specific needs and what is already available in the libraries/code provided.
For anyone who comes to this question and are looking for answers, you may want to try xInterop NGen++ , a C# wrapper generator for native C++ DLL, which has been just released to the public, the tool can generate C# wrapper for native C++ DLL automatically and instantly by using advanced P/Invoke technologies. Check out the current version and a free version will be out soon.
(I am the author of the tool)
The header file used by the C++ dll contains a few user defined type definitions and function declarations.I have browsed many sites and all the posters say that its not possible to import header file into C#.I would like to know if there is any way to import header file into C# code as it is required to declare the functions of the imported dll in the C# application class.
Thanks
This is more or less a duplicate of Importing a C++ dll in C# however that question has some poor "information lite" answers.
Unfortunately there is no short answer to this, however you do have several options.
Wrap your C++ class in a managed C++
class. Then your C# project just
references the managed C++ project,
and everything works.
Like 1, create a managed C++ class,
but create a facade. This a
simplified interface to your class
exposing only the functionality you
need.
The other approach is to use PInvoke
to call the methods on the class.
You'd need to built a C#
representation of the class for the
pinvoke calls. This can be
problematic and involves a lot of
trial and error if you don't know
what you're doing.
All of the above involve learning some technologies that will be new to you (manged C++ or the intracies of PInvoke). Unfortunatly there's no other way.
If you can I'd go with 2.
Have you considered bridging this gap with a C++/CLI project? If you write all your wrapper library and interoperability code in a C++/CLI project you can easily define managed types that expose the defines in C/C++ header files.
When I have submbled upon the same problem - given .h and .lib files intended for C/C++ use, I have written a wrapper for it in C++ with managed extensions. It is really quite simple. Your C++ assembly will play neatly in your Visual Studio solution and you'll be able to single step right from C# into managed C++ into unmanaged C++ and back again light as a breeze! :-)