I heard somewhere that you can drop down to C++ directly inside C# code.
How is this done? Or did I hear wrong?
Note: I do not mean C++ / CLI.
You might be thinking of unsafe blocks where you can write code that looks a lot like C++, since you can use pointers.
You heard incorrectly.
You can drop down to Assembly from C, because C is instruction-set-semi-agnostic Assembly.
You can drop down to C from C++, because C++ is C plus some other things that make it divinely ugly or horrifically beautiful, depending on your perspective.
You can't drop down from C# to C++, because they are entirely different things. There is no direct relation between them, aside from the curly-brackets-and-semicolons syntax. C# is not a superset of C++, nor a subset of it, nor a sibling of it (but perhaps a second cousin).
That said, C# provides facilities for interacting with external code at all levels of abstraction, from Platform-Invoke (calling functions written in C) to COM to a wide variety of other kinds. But C# itself is not directly related to these things.
Why would you need to do that? You can reference native C libraries, but I doubt very much that you can run native code from within managed code.
You can interact with COM objects very easily from .NET.
Related
If you had to decide between C# and Managed C++, which would you choose and why?
Are there benefits of Managed C++ over C#? Which language do you prefer? What decisions would you make under what circumstances?
I would use managed C++ if I:
Needed to integrate with existing C/C++ code
Needed to port existing C/C++ code to .net
Needed to use .NET objects from C++
Needed to expose .NET object over COM in a more complex way than what .net makes easy
Needed to access hardware directly
Needed to call lots of unmanaged APIs
And already had some skills in C++, as the above tasks will need a experienced C++ programmer. Most of the time I would only consider managed C++ if the company already had a C++ code base, otherwise who is going to maintain the managed C++ code.
In other cases I would always choose C#. Even if I choose managed C++ for part of the system, I would try to write as much of the system as possible in C#.
Think of manage C++ as a bridge building kit for going between the
unmanaged world of C/C++ and the
managed world of .NET.
If you only need to call a few simple APIs from C#, then see pinvoke.net and this overview to find how to call them from C#, as a few lines of complex pinvoke code (prebuilt bridge) in C# is normally better then introducing C++ to a project that is not already using it.
what is the benefit of managed C++
over C#?
C++.net is useful for interacting with C++ and C code (that is, calling external C or C++ libraries, providing callback functions to external modules written in C or C++ and so on.
what language of both would you
prefer?
I would prefer C# for all situations except the one described above (interacting with C and C++).
C# is easier to write, simpler, and geared specifically to use the .NET platform. C++ can do it also, but it has all the complexity of the C++ language plus the extensions needed to use the .NET platform.
Unless you need to interact with native C++ or C code, you're better off using C# in most cases (that is, if you're coding for the .NET platform).
Normally I prefer C++, but when needing to code for .NET, it doesn't beat C#.
Managed C++ is good for interop with C++: for example, if you have a .NET application and your assembly has to interact with a native interface that comes as C++ .lib files (which I had more than once), or with a nice C++ API.
Example: Rithmic (not that you ever heard of them) until recently ONLY supported a C++ API. If you try to access them from C# - good luck ;) Managed C++ allows me to access their API and expose nice .NET objects.
Basically interop. Managed C++ REALLY shines in interop with low level C / C++ API's.
I used managed C++ when I needed to build up new NET component with much ofC++ unmanaged code inside.
I did a specific class used to Marshall some objects forward and back from old C++ code.
I've encountered a problem which was transparent in managed C++, but made a big headache in C# - I had to send a callback function to a C++ unmanaged library, that defined this callback as __cdecl. In C#, the default calling convention is __stdcall, and it is pretty compilcated to move a C# delegate from __stdcall to __cdecl (Actually it requires either a 'shim' unmanaged DLL to do so or using some reflection classes).
In C++, (C++.Net as well), it is just a simple attribute.
I haven't personally written, or read for that matter, too many lines of code in managed C++, but from what I have seen it looks too convoluted and patchy. That said, you might want to use managed C++ if you are really good in C++, and when learning the idioms and patterns of a new language would be too much of a risk.
Use C# if you are quite competent in it. If you are only getting started with C++ and C#, I think, C# is the easier route to take.
I would prefer C#, or specifically .NET, over C++ because of the extensive .NET standard library.
First of all, until now, all my programming education, has been targeted to console applications, just like everyone who starts learning C and C++. (the 2 languages i know)
Now, i want to jump to the nice graphical World.
So, I am exploring Windows Forms, i have already got many headaches trying to understand the language that it uses (quite diferent from native C++), but i managed to do a couple of things like using textbox and buttons.
Well, the thing is, i have read in many places that, in order to avoid headaches trying to code winforms in C++, i'd better "Build the GUI in C#, because it's way easier, and the logic, and code in C++". And that is my question, i don't understand that statement, at all.
What is that supposed to mean?
Also, it's C# THAT similar to C++, as to affirm that statement? Cause, if C# was too diferent to C++, i would have to learn the whole C# language
hope you understand my doubt.
PD : Sry about my bad english.
Joan, while it is certainly possible to develop an applications Front End in C# and the logic in C++ I believe it to be a huge waste of effort to do it this way since you only complicate yourself for no real benefit since you can code both things in the same language.
C# has many advantages over C++ and I personally use mostly C#, but I can clearly see many programmers who love C++.
Now going into your question regarding the similarities between C++ and C# the answer is yes and no. Yes in the sense that C#'s syntax is clearly derived from C++. Many things like ifs and for loops are written exactly the same, so if you know how to write an if in C++ you can write it in C#.
The difference (and a critical one that is) lies in the way the languages work. C++ is an strictly compiled language (it goes from C++ code to machine code). C# is an interpreted language (it goes from c# to MSIL and during runtime to machine code). In C# you can't use pointer arithmetic without explicitly allowing, in C++ you can (and will) use pointer arithmetic. C# has garbage collection, C++ does not.
In the end, as I said in the first paragraph you can use both languages to build an application, but it would be highly complicated. My advise to you is to learn a bit of C# and then decide which language you would prefer to build your GUI application. But don't believe even for a second that C++ can't be used to build a front-end since there are a myriad of frameworks for that. One I remember from the top of my head is Qt.
Another option for you is to use "C++/CLI" which is a flavor of C++ which can use the .NET Framework (the same framework C# uses)
EDIT: Thanks Jerry for pointing out that Managed C++ is obsolete and that C++/CLI is the one!
C# has braces, semicolons, and uses the concept of classes. It has "C derived" syntax, but otherwise is very dissimilar to C++. Java is really the precursor to C#, not C++.
You can build application GUIs using C#, and then use various methods of calling into C++ (such as P/Invoke). Unless you are using lots of existing libraries, or looking for absolute performance, its going to be a headache.
If you are looking for examples of modern Windows GUIs using C++, take a look at the Hilo example program.
It is not very difficult to switch to a new language. The few keywords you would have to learn are not the issue. What costs most energy if to get used to the new environment and class libraries. That is probably what you mean and it is true, you'll need some time.
Now coming to the split GUI in C# and code in C++, then you'll have to make all bindings and marshalling of parameters if there are buffers and strings for example. I don't think this would make your life any easier. Interfacing with native Dlls can become some pain. However if you use third party dlls and have already a large working codebase you could try to compile the logic code with /clr enabled. This generates a DLL that can be used from within .NET directly.
NOTE: WinForms is now out-of-date for new applications, consider using WPF instead. It scales nicely, but the learning curve might be steep for newcomers.
Please note that you have native C++ and C++/CLI, the first one is the one you have learned, but the second one is the one you will need to use if you want to combine it with a C# GUI. However, I would suggest you to stay away from C++/CLI because this will cause a lot of confusion if you don't have a solid ground in C++, C# and .NET.
The reason that you can't use the native C++ is because C# is a managed language, so you will either have to find another GUI that fits with C++ or you will have to go C# for everything. For more information about managed see the environment part of Difference between C++ and C#, the article will also provide you with a good comparison between both.
Well, this aint a direct answer but hope it will help you. Since you stated that, you are just started and you want C++ combined with GUI, I suggest you to take a look at Qt. IMO I found C++ and GUI made easy in Qt. Also it's good too.
Although it's not a direct response to the question you're asking, I'd first caution that WinForms are already basically a dead-end, so for new code you'd be much better off avoiding them. If you're going to do a GUI in .NET, the currently preferred choice is WPF.
Some people find C# an easier way to do a GUI. It's definitely true that Microsoft provides considerably more in the way of Wizards and such to do it with little or no coding if you use .NET for the job. Other people (especially those with more experience doing so) can produce a GUI in C++ just quickly (or even a little more so) using C++ instead.
Mixing languages like this can work well in relatively large projects where you have completely separate teams of people working on the different parts. For smaller projects where the same people typically work on both parts, the difference in syntax is at just about the worst possible level -- not enough different to really shift gears and think differently, but still enough different that you can't plan on just typing things and having any hope of them compiling. All in all, you're usually a lot better off picking one language and sticking to it.
I need to access code in a native C++ DLL in some C# code but am having issues figuring out the marshaling. I've done this before with code that was straight C, but seem to have found that it's not directly possible with C++ classes. Made even more complicated by the fact that many of the classes contain virtual or inline functions. I even tried passing the headers through the PInvoke Interop Assistant, but it would choke on just about everything and not really no what to do... I'm guessing because it's not really supported.
So how, if at all possible, can you use a native C++ class DLL from .NET code.
If I have to use some intermediary (CLR C++?) that's fine.
There is really no easy way to do this in C# - I'd recommend making a simple wrapper layer in C++/CLI that exposes the C++ classes as .NET classes.
It is possible to use P/Invoke and lots of cleverness to call C++ virtual methods, but I wouldn't go this route unless you really had no other choice.
You might have a look at SWIG, if nothing else just to see how they handle the basic wrapper code (which SWIG generates). I know next to nothing about C# native code bindings so I can't judge if their approach is sound, but they do a decent job with some of the other language bindings.
Is is possible to make a GUI in C# but make the actually program in C or C++.
Like say I want to make a chat application. I want the interface to be in C#. But I want to make all the actual code in C.
Is this possible?
I found http://www.google.com/search?hl=en&q=P%2FInvoke&btnG=Google+Search&aq=f&oq=
does anyone have any better kind of information?
Absoluely! A c# winform can call into managed or unmaged C or C++ dll's. See P/Invoke for more information.
Edit: Turns out there's a good thread on P/Invoke on the front page. :)
You already have some answers here giving you the affirmative.
One suggestion tho: Premature optimization is the root of all evil (or something like that).
Unless you are creating a science project (doing something just to see if it can be done), just write the entire thing in C#.
Once complete, if you find you have parts of the project that are not performing well enough, rewrite those parts.
Basically, the part of the application that are slow are rarely where you thing they will be.
Incrementing on JP's totally correct previous answer, you can also expose your C++ code through COM interfaces and then consume them in C# via COM/Interop. Good luck, though.
Not only is it possible, it might very well be what you should do. There's no reason to rewrite all of your existing code for .NET.
In short, there are three ways to use existing (C/C++) code from C#: for easy access to a few simple APIs, P/Invoke works well. C++/CLI will give you the most flexibility. You third option is to use COM.
Everything you can do in C can be done in managed code. Why do you want to build one component in C# and the other one in C? Are you worried about sockets?
But to your question, you can absolutely do it as JP mentioned above.
Depending on how you want to distribute your application, you should consider the deployment requirements. If you have C++ modules, you will have a dependency on the C++ runtime libraries, in addition to the .Net framework. This is a non-issue if you are merely P/Invoking the Win32 API.
This may or may not matter to you, but it mattered to me - I got rid of the C++ layer in my app, and resorted to calling Win32 directly.
I would like to call my unmanaged C++ libraries from my C# code. What are the potential pitfalls and precautions that need to be taken? Thank you for your time.
There are a couple routes you can go with this - one, you can update your unmanaged C++ libraries to have a managed C++ extensions wrapper around them and have C# utilize those classes directly. This is a bit time-consuming, but it provides a nice bridge to legacy unmanaged code. But be aware that managed C++ extensions are sometimes a bit hard to navigate themselves as the syntax is similar to unmanaged C++, but close enough that a very trained eye will be able to see the differences.
The other route to go is have your umnanaged C++ implement COM classes and have C# utilize it via an autogenerated interop assembly. This way is easier if you know your way around COM well enough.
Hope this helps.
This question is too broad. The only reasonable answer is P/Invoke, but that's kind of like saying that if you want to program for Windows you need to know the Win32 API.
Pretty much entire books have been written about P/Invoke (http://www.amazon.com/NET-COM-Complete-Interoperability-Guide/dp/067232170X), and of course entire websites have been made: http://www.pinvoke.net/.
You're describing P/Invoke. That means your C++ library will need to expose itself via a DLL interface, and the interface will need to be simple enough to describe to P/Invoke via the call attributes. When the managed code calls into the unmanaged world, the parameters have to be marshalled, so it seems there could be a slight performance hit, but you'd have to do some testing to see if the marshalling is significant or not.
The easiest way to start is to make sure that all the C++ functionality is exposed as 'C' style functions. Make sure to declare the function as _stdcall.
extern "C" __declspec(dllexport) int _stdcall Foo(int a)
Make sure you get the marshalling right, especially things like pointers & wchar_t *. If you get it wrong, it can be difficult to debug.
Debug it from either side, but not both. When debugging mixed native & managed, the debugger can get very slow. Debugging 1 side at a time saves lots of time.
Getting more specific would require a more specific question.
You can also call into unmanaged code via P/Invoke. This may be easier if your code doesn't currently use COM. I guess you would probably need to write some specific export points in your code using "C" bindings if you went this route.
Probably the biggest thing you have to watch out for in my experience is that the lack of deterministic garbage collection means that your destructors will not run when you might have thought they would previously. You need to keep this in mind and use IDisposable or some other method to make sure your managed code is cleaned up when you want it to be.
Of course there is always PInvoke out there too if you packaged your code as DLLs with external entrypoints. None of the options are pain free. They depend on either a) your skill at writing COM or Managed C wrappers b) chancing your arm at PInvoke.
I would take a look at swig, we use this to good effect on our project to expose our C++ API to other language platforms.
It's a well maintained project that effectively builds a thin wrapper around your C++ library that can allow languages such as C# to communicate directly with your native code - saving you the trouble of having to implement (and debug) glue code.
If you want a good PInvoke examples you can look at PInvoke.net. It has examples of how to call most of win api functions.
Also you can use tool from this article Clr Inside Out: PInvoke that will translate your .h file to c# wrappers.