I have a C++ program that I wrote, and I would like to give it a user interface. Is there any way I can run a C++ program and put the information from the program onto the UI of a VB Application?
Sure.
Use
COM
COM Interop
P/Invoke (a.k.a. Declare in VB)
Oh, I forgot: C++/CLR if you intend to use Windows only
I suggest you write the whole application in a managed language (e.g. VB.Net) and only invoke C++ library functions for the performance critical work (or for legacy code that you already have, of course).
I think the easiest solution would be to put your C++ code into a DLL, and call your code from VB. Have a look at this article for more information...
http://www.codeproject.com/kb/DLL/XDllPt1.aspx
you can mix C++ and .NET
easiest is if you target your C++ code to the CLR, but you can also mix .NET and native code.
either way you basically make your C++ program a library your VB code can use.
Related
I have a C++ app from which I want to call .NET (C#) methods. I was going to use C++/CLI, but it is only supported on Windows.
Since also we support the MAC, I'd like to call .NET from C++ in a way that will work on both Windows and Mac (with Mono).
What is the best way to do this?
EDIT: I should add that the c# code we wish to call is not ours. We have no way of making any changes to it. The c++ code, of course, is ours.
The easiest way is to expose the functionality via a function pointer. Both .Net and native code can interop with C/C++ code in the form of a function pointer. Function pointers are supported on all platforms where C++ code runs hence it can be written without any understanding of .Net.
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Possible Duplicate:
What is the difference between Managed C++ and C++/CLI?
What is CLI/C++ exactly? How does it differ to 'normal' c++?
I am in doubt of distinguishing between C++ and C++.NET.
Is that right C++ is unmanaged code and C++.NET is managed code?
I need to program for a project in C++. For better building the GUI, I would prefer to use C++.NET.
I also have another plain C++ library (unmanaged C++ DLL file), will it be possible to use it as a normal DLL library in the C++.NET project?
Is that right C++ is unmanaged code and C++.NET is managed code.
There's no such thing as "C++.NET". There's C++/CLI, which is basically C++ with Microsoft extensions that allow you to write code targeting the .NET framework. C++/CLI code compiles to CLR bytecode, and runs on a virtual machine just like C#. I'll assume you're actually talking about C++/CLI.
With respect to that, one can say standard C++ is unmanaged and C++/CLI is managed, but that's very much Microsoft terminology. You'll never see the term "unmanaged" used this way when talking about standard C++ unless in comparison with C++/CLI.
Both standard C++ and C++/CLI can be compiled by the same Visual C++ compiler. The former is the default on VC++ compilers, while a compiler switch is needed to make it compile in latter mode.
I need to program for a project in C++. For better building the GUI, I
would prefer to use C++.NET.
You can build GUI programs in C++ just as well as C++/CLI. It's just harder because there isn't a standard library in standard C++ for building GUI like the .NET framework has, but there are lots of projects out there like Qt and wxWidgets which provide a C++ GUI framework.
I also have another plain C++ library (unmanaged C++ dll), will it be
possible to use it as a normal dll library in the C++.NET project?
Yes. It might take some extra work to deal with the different standard C++ data types and .NET data types, but you can certainly make it work.
Managed C++ is a now deprecated Microsoft set of deviations from C++, including grammatical and syntactic extensions, keywords and attributes, to bring the C++ syntax and language to the .NET Framework. These extensions allowed C++ code to be targeted to the Common Language Runtime (CLR) in the form of managed code as well as continue to interoperate with native code. Managed C++ was not a complete standalone, or full-fledged programming language.
Managed C++
#using <mscorlib.dll>
using namespace System;
int main() {
Console::WriteLine("Hello, world!");
return 0;
}
Vanilla C++
#include <iostream>
using namespace std;
int main()
{
cout << "Hello, world!";
return 0;
}
Well... C++ .NET is kind of a misnomer.
You can program in C++ using visual studio .NET. Well that's what it was called along time ago. Now a days folks just call it Visual Studio, with the dot NET moniker. Well, at least the splash screen doesn't have a big ol .NET in the logo anymore.
It is kind of understood that using Visual Studio (VS), you can program in managed and unmanaged languages (Lots of choices there btw).
If you want to program in C++ using Visual Studio you have two choices:
Unmanaged or native C/C++. This is the old (or new I guess too) C++
that you have always known, and you program with unmanaged memory.
Managed C++. They call this C++/CLI. That is read C++ over CLI, not
C++ divided by CLI! This is C++ that has extra keywords, and a few
extra syntax elements than the native C++. This allows you to
utilize the .NET Foundation Class Library and do other fun things in
the .NET framework. This of course uses the garbage collector for
memory for managed types.
Personally my favorite language is C#, but if you need to interop between C++ and .NET than definitely use Managed C++. It is very easy to do, and I think is easier than that other P/Invoke stuff.
If you are going to some project, I would suggest you do your UI in C# and take advantage of all that it has to offer. Then have that reference a mixed mode managed library that contains your C++ code. I think that will be a lot easier for you.
The answer to your last question is yes, you can definitely use that in your app.
Here is how the dependencies would work:
[C# App/GUI] depends on [Managed C++ assembly] depends on [Native C++ Lib]
Yes, C++ is unmanaged code and C++/CLI is managed.
Yes, you can use your unmanaged C++ DLL in your C++/CLI project. But you have to write a wrapper for that. That means you have to define the unmanaged methods you want to access in your C++/CLI project.
Example:
using System.Runtime.InteropServices;
[DllImport("YourDLLName")]
public static extern void UnmanagedMethodName(string parameter1);
I currently have an old unmanaged C++ DLL using MFC. This DLL has a bunch of code which is multi-threaded and written back in 2003 using VC6. This code sadly doesn't work anymore.
I've been tasked with finding an alternative way of running this multi-threaded code so that it does function as intended. Someone before me had already rewritten it in C#, and I need to port that C# code over to VC++. I did some research and realized that I could save some time in the porting process by just porting the C# code to VC++ (using the .NET framework). But then I realized that my old MFC DLL cannot run this .NET code.
My idea is to write this multi-threaded code in a VC++ DLL (using the .NET framework) and using some form of interoperability to be able to call the functions from the old DLL to the new DLL.
I have looked into COM interoperability as well as wrapper classes. What is the best way of accomplishing this? Are there any tutorials that could help me with this task? (I've already done some extensive searching and there are a lot of tutorials using unmanaged C++ DLLs to C# DLLs, but not much that pertains to my situtation).
Just so you know, I cannot compile the old DLL with /clr as this DLL is hosted in an old Win32 application as well. Compiling with /clr causes the application to crash, or else this would have already been done.
TO CLARIFY: I'm curious as to why calling functions residing in a C# DLL from an unmanaged C++ DLL through a COM interop seems so simple compared to doing the exact same thing using a managed C++ DLL. I even have a proof-of-concept between C# and C++, but I can't for the life of me begin to understand performing the exact same task with C++. Does there happen to be just a simple tutorial for calling just one simple (let's say 'Add') function from unmanaged C++ to managed C++?
If you have a (managed) DLL, regardless of the language(s) it is written in, you need a process to run it in. If you have a native process that -- for whatever reason -- must not use the CLR, that you cannot directly use a managed DLL (any code that depends on the CLR in-process) from this process directly.
You would need a second helper process that runs the managed DLL and, for example, exposes a COM interface that the native process could call. (out of process COM server)
I have looked into COM interoperability as well as wrapper classes. What is the best way of accomplishing this?
Not sure what you mean with wrapper classes, but an out of process COM server for your managed DLL could do the trick. (Obviously, this is quite some overhand wrt. to managing the proper registration and startup/shutdown of the helper process.)
Breaking the problem up a bit (as far as I understand):
[oldish Win32 app (no! CLR)]
<- normal DLL interface -> [native/MFC DLL (no! CLR)]
<- via COM -> [stuff in a separate executable]
If this is what you are looking for, then this article (just a quick Google hit) may be helpful:
http://www.codeproject.com/KB/COM/BuildCOMServersInDotNet.aspx
For COM in general, I think any COM tutorial should cover what you are supposedly trying to do.
I have a simple (and also trivial) banking application that I wrote in C++. I'm on ubuntu so I'm using GNOME (GTK+). I was wondering if I could write all my GUI in C/GTK+ and then somehow link it to my C++ code. Is this even possible?
Note: I don't want to use Qt or GTKmm, so please don't offer those as answers.
Yes, it's a very easy thing to do. All you have to do is expose some of the C++ functions as "extern C" so that the event handlers and callbacks in your UI code can call them.
In the case that you can't change the existing C++ source - no problem. just write a C++ shim for your UI, extern those functions, and call backend functions from there.
I don't see why not, with appropriate extern "C" usage so your C code can call into C++. Now, granted, you're probably making it a bit harder on yourself, but it's theoretically sound.
Like others propose you can write a C wrapper for your C++ library. But you can also write the front-end in C++, even if you only use the C subset. I can understand if you don't like the language mixing, but it is the easiest way, because you save the time to write the wrapper.
How about using wxWidgets instead?
You can just compile your GTK/C code as C++ without using GTKmm, and use the C++ code natively.
Most sane C libraries can be used from native C++ code, and GTK+ is fundamentaly a C library.
So, one commonly heard comment when talking about performance is that you write your code with whatever language gets the job done fastest. If performance in specific areas is a problem, then rewrite those bits in C/C++.
But, what if you're starting with a native C++ app? What options do you have if you want to write the easy bits, or refactor the old bits, in a language like Python, Ruby, C#, or whatever? Keep in mind that transferring data between the native and other sides is a must. Being able to simply call a function written in an "easier" language, while passing C++ classes as data, would be beautiful.
We've got a crusty Win32 app that would benefit greatly if we could crank out new code, or refactor old code, in C# or something. Very little of it requires the complexity of C++, and dealing with the little fiddly bits is dragging down the programming process.
As Aaron Fischer suggests, try recompiling your C++ application with the /clr option turned on and then start leveraging the .Net platform.
CLI/C++ is pretty easy to pick up if you know C# and C++ already and it provides the bridge between the .Net world and native C++.
If your current C++ code can't compile cleanly with /clr turned on then I'd suggest trying to build your application as a static lib (without /clr enabled) and then have your main() be in a CLI/C++ project that calls your legacy app entry point. That way you can at least start leveraging .Net for new functionality.
For examples of "legacy" C/C++ apps that have been "ported" to .Net CLI/C++ check out the .Net ports of Quake 2 and Quake 3: Arena.
Well, it really depends on the language. Python interfacing, for instance, is most easily done with Boost Python, and many other languages will require you to interface them as you would with C, using their C library and declaring your callbacks to be extern "C" (unfortunate that you can't use the C++ class definitions in other languages usually).
But I would also ask what you intend to use it for as C++ is a complex language, but once you get familiar with it, it is very powerful and not very much harder to code than other languages. The only really good exception I could think of is if you plan on using a powerful library that exists only in one language and there isn't a decent C++ alternative (graphics libraries are probably the best example of this because you have to be very familiar with them to use them effectively).
It's also worth pointing out that if you interface C++ code to another language, you lose out on the inter-platform compatibility granted by that language.
If you want to work between C++ and Python, than Boost Python is what you're looking for. You can write C Python bindings by hand for Cython, but that limits in many ways how you're going to write your code. This is the easiest way, as seen in some snippets from this tutorial:
A simple function that performs a hello world:
char const* greet()
{
return "hello, world";
}
The Boost python code needed to expose it to python:
#include <boost/python.hpp>
BOOST_PYTHON_MODULE(hello_ext)
{
using namespace boost::python;
def("greet", greet);
}
How to use this code from python:
>>> import hello_ext
>>> print hello.greet()
hello, world
Going in the opposite direction is bit tougher, since python doesn't compile to native code. You have to embed the python interpreter into your C++ application, but the work necessary to do that is documented here. This is an example of calling the python interpreter and extracting the result (the python interpreter defines the object class for use in C++):
object result = eval("5 ** 2");
int five_squared = extract<int>(result);
You can change the common Language run time support in your c++ project to /clr. From this point you can use any .net functionality right in your c++ code. This includes creating winforms in your project as well. You can also add a c# library that handles ui and other functionality.
In the .NET world you always have the option of crreating a COM/ActiveX interop layer for your C#/VB.NET assembly.
You can then use the normal COM API from your C++ application to create an instance of this COM server that actually wraps your .NET assembly.
Good thing about this is that simple parameters such as int, bool, string, float etc are mapped to their COM equivalent for you. However to my knowledge it is not possible to easily pass full .NET objects (instances of classes you create).
Also be aware that COM interop calls are relatively slow. You should not be calling a COM interop method continually from your C++ code in a tight loop.
COM/ActiveX have traditionally relied on the Windows Registry, not ideal as it is a big dependency. However it is also possible to to use Registration-Free COM interop to avoid this dependency.
This article covers the steps required to register a .NET assembly for COM interop.