I am very new to C#, and i am trying to use a help package for my project.
The package is written in c and has
1) /bin/ several .dll files
2) /include/ has a header file
3) /lib/msvc/ .lib file
my question is how can i use those files in my C# WPF project?
i know there is no "#include" in C#, and the .dll can not be imported by adding to the project's reference. so how can i do it in C#?
Thanks
You need to add a series of C# Platform Invocation method definitions. This tells C# how to call into the .dll, and use the C API directly.
The header and library files are completely unused.
Just adding to the answers, you may want to take a look in this blog post. It has a link to a Visual Studio addin that can generate P/Invoke signatures from your headers.
Best
You might find managed C++ useful. You can write a managed C++ library that uses the header files and the .lib directly, and wraps them with a set of .NET classes to be used by C#.
You need to use pInvoke
http://msdn.microsoft.com/en-us/library/aa288468%28VS.71%29.aspx
There are a lot of ways to do this "interop" - I once did a talk called "head spinning interop". The key is the structure of your native DLL. Since you say it's in C, the chances are it's in perfect shape to be used with PInvoke, which works best with C functions or C-style functions in C++. The other answers have excellent pointers to the syntax and some help to get your function (and the parameters it takes) declared on the C# side.
The other two main options are a C++/CLI wrapper, a good choice when the functions take a lot of complicated types, or COM, which would almost certainly require you to change the native code so is not a good fit in this situation.
Related
I have a problem with two projects. My main project is in C++. Another one is in C# and it is measuring current network bandwidth (updated every second). What I need to have is that C++ project can get those values.
Mt first thought was to let the C# export calculated values to .txt file. Another project could read those values. But problem is that it would mean that both would use that file at the same moment what seems to be impossible (or maybe I could synchronize it somehow?)
I was reading a lot about creating and using library, but it looks complicated to me.
Are there any other ways to do that?
Please, I need help...
The simplest way is using stdin / stdout for this purpose. Just write the values to Console from the C# program and read it from pipe in the C++ program.
Or maybe you'd like to extend your project to C++/CLI (.NET-based C++ extension) and directly reference your C# library.
As well as the other options outlined by the others, you also have the option of making the functionality of your c# code into a DLL and then calling that from your C++ code to allow you to use the functionality of the DLL to get network information. I have a how-to type link here on how to create a C# DLL. You can then reference said DLL in C++ and utilise its functionality as needed.
Hope this helps, and let me know if you need any further information:)
Attempting to build a C# NPAPI plugin I have found a tutorial which describes that your dll needs to implement a number of methods such as NP_GetEntryPoints , NP_Initialize and NPP_New along with a number of others.
However what I want to understand is if I can simply mirror these method names and construct equivalent datastructures as described in the article (like _NPPluginFuncs) in C# and everything will work?
Could someone please be kind enough to provide some guidance? Is it possible to build a NPAPI plugin in C# and if so what are the basic steps involved?
As stated in the documentation:
A NPAPI browser plugin is, at it’s core, simply a DLL with a few specific entry points
That means you need to export some function from a regular dll, that is done usually in C/C++. Unfortunately it is not possible to expose any entry point from a plain C# dll, but look at this answer, with some effort it appear to be possible to trick some export by some sort of post build tool.
In any case don't expect to pass too much complicated data structures from/to the plugin interfaces, it will be a pain. If you are interested in doing more research the keywork to use is "reverse P/Invoke", in analogy with direct P/Invoke that is calling regular dll from managed world.
The reason a C# dll can't expose directly "entry points" is that entry point are actually just some address inside the dll poiting to some assembly code immediately executable. C# dll are different kind of beast: they are just files containing IL that is compiled "Just In Time" and indeed such compilation is forced AFAIK with some OS tricks. This is the reason reverse P/Invoke is not starightforward at all.
As Georg Fritzsche says in his comment:
NPAPI plugins are basically DLLs with a few required C-exports
and there is no built-in way to export functions (in the C-export sense) from an assembly written in C#.
Some of your options are:
A mixed-mode C++ assembly which can export the functions directly. This could have implications for hosting the CLR in your plugin's host process.
A small native DLL which hosts the exports, then uses COM interop to delegate to a C# assembly containing the plugin functionality. The "official" way to do so-called "reverse p/invoke".
An intriguing project which post-processes your fully-managed assembly, turning static methods marked with a custom attribute into named function exports. (I have no affiliation with this project; I stumbled across it after I got to wondering whether anyone had improved on the COM interop way of doing things.)
I'm a Linux C++ developer, and I need to write C++ dlls for windows, which is to be used in C# applications.
The problem is importing the DLLs into C#, which I have no idea how to do it. In my friends' project its probable that any kind of unmanaged dll will be used, and I'm charge of doing this :-D
I need to import all objects and functions in the DLL, and my search has led me to nothing more than DllImport and so.
Thanks so much for helps.
You can use C++/CLI as a wrapper for your unmanaged C++.For more info on C++/CLI and what it does you can use this link
http://www.functionx.com/cppcli
You can have a quick look at this
http://www.codeproject.com/Articles/19354/Quick-C-CLI-Learn-C-CLI-in-less-than-10-minutes#A8
you want DllImport
There's a bunch of info here :-
http://msdn.microsoft.com/en-us/library/aa288468(v=vs.71).aspx
and lots lots more all over google, and many stackoverflow questions related to DllImport
There are many ways to go about this. You can write a CLR dll in C++ which puts an interface that C# can directly "talk" to. This is a nice option cause you can keep native C++ still and not have all of your code be CLR based.
Do some searches for C++/CLI
You can also use dllimport and friends and create a standard dll.
Have you thought to keep the Dll's in C++ (port then recompiled under VS.NET) less effort than a C# port.
I have in the past made a shared memory DLL to allow LabVIEW (Windows7) and a Winforms C#.NET appl. to share data storage via this dll.
Take a look at this tutorial. It shows two methods for accomplishing what you want: How to Marshal a C++ Class
I have some code in C# which I want to use in other project (coded in C++).
From what I researched, I need to create a .lib but MSVS only creates .dll (I think..). I think is possible to use the .dll by using LoadLibrary() over C++ but seems not very friendly.
1 - Can I create the .lib in MSVS? If not, how can I create it.
2 - What is the best way to integrate the code? By the .lib or using .dll + LoadLibrary()?
The easiest option, honestly, is to use C++/CLI. That lets you use both object systems (.NET, and traditional C++ with its standard template library).
Is it managed C++ ? If so you can directly add a reference to the C# dll and use it.
What you need is a com compliant class in c#:
http://en.allexperts.com/q/C-3307/2008/2/Using-C-class-C.htm
http://blogs.msdn.com/b/deeptanshuv/archive/2005/06/26/432870.aspx
One possibility is to make your C# code Managed COM compliant. Then use the standard COM api's (QueryInterface etc) to call the C# COM code.
The codeproject sample may be useful
http://www.codeproject.com/KB/cs/ManagedCOM.aspx
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! :-)