I've been on a quest for a while now to pass the PCM of an MP3 from W8.1/WP8.1 to Unity3D and I believe I'm getting close. I was referred to this project which works absolutely fine but, of course, it's in VB.NET so it can't be used with Unity. VB and C# are fairly similar so I set out to translate it. You can see my translation at this pastebin.
The problem occurs on line 97. The app simply exits with absolutely no indication of what went wrong. Calling any non-inherited function on the interfaces IMFSample and IMFMediaType has the same effect.
A friend suggested getting the HRESULTs from these functions to see if anything shows up. Google shows getting HRESULTs from COM interops in C# is.. hard. I experimented by changing IMFSample.GetSampleFlags to
int GetSampleFlags(out int pRetVal);
And that returned "The requested attribute was not found. (Exception from HRESULT: 0xC00D36E6)" and I'm not really sure what to do with that information...
So, I humbly ask you all... just... just what? What do I do from here?
--- SOLUTION ---
So as it turns out the solution was a little dumber than I expected.
I did not know this, but apparently COM interfaces that inherit from other COM interfaces have to include ALL of the methods from the parent COMs. Otherwise windows, it seems, throws a hissy fit.
That was it... it was my own laziness in the first place that killed me.
I created dll from c function and importing into c#
When I call the dll function I am getting error:
Unable to load DLL 'subFunction.dll': Not enough storage is available to process this command. (Exception from HRESULT: 0x80070008).
How to fix it.
I am inclined to say you look at it from the wrong side - this is not a C# issue, it is a simple as it is error in C++. I suggest you put up a native C++ command line test and check whether this happens there too, then you go on and fix your code.
Without debugging we are sort of guessing what you made wrong - and that will never work. BUt this seriously looks like C# is totally irrelevant for the question and it is a pure C level issue.
For my university course I want to make system for learning programming. The main idea is writing code through debug, just look at picture (from Bret Victor video):
I don't want to make my own compiler (just becouse it's very complicated and hard, especially for C# language), so I want use all features of .NET and other libraries. I see there two ways:
Rewrite code by replacing assigments to assigment & sending debug information to main program
Compile code and debug it -> ...
Anyway, I need some start point. What classes and libraries I must google, in which manuals I can read useful information, what is the best way to implement it?
I think what could work is, if you just treat C# as a script language. There are multiple tutorials on how to use C# within C# as a script language, like this one. So you just start the "script" compiler again on predefined conditions (like a line break) and if the compilation is successfull you return the result in your second pane. This is just a basic idea.
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Is it possible to make a call to a C# application from a C++ application?
I am playing with the idea of writing a proof of concept application that contains a script engine that runs (executes) a .CLI language (e.g. C#, VB.Net etc).
I had originally wanted to create the script engine application in C++, but that appears to be fraught with problems and work arounds. Instead, I want to write the script engine in C# instead now.
I have sketched together a very rough idea of what it is I'm trying to do below:
The code is still pseudo C++, but hopefully, the semantics should be clear:
class GenericDotNetLangInterpreter
{
public:
Results run(const Arguments& args);
protected:
GenericDotNetLangInterpreter(const std::string &script);
};
class MyInterpreter : private GenericDotNetLangInterpreter
{
public:
MyInterpreter(const LanguageType l);
Results run(const Arguments& args);
}
Couple of questions:
Has someone done this kind of thing before, and is there some code I can use as a reference point?
what are some gotchas I need to be aware of going down this path?
Not really an answer, but pointing out that C# and VB.Net aren't interpreted, but compiled to IL (similar to Java's Bytecode). In other words, your API name and signature would probably change. You would need to invoke the associated compiler and then execute the code.
There are .Net languages that can run interpreted on the DLR, but I'm not clear on calling that from a native language.
The limit between managed and unmanaged applications is thinner than it looks. Your C++ app can link with mscorelib (basic .NET support).
From there on, your C++ app can compile your text "script" to .NET byte code and execute it.
Whether it makes sense or is a good idea is left up to you.
I have a small to medium project that is in C++/CLI. I really hate the syntax extensions of C++/CLI and I would prefer to work in C#. Is there a tool that does a decent job of translating one to the other?
EDIT: When I said Managed c++ before I apparently meant c++/CLI
You can only translate Managed C++ code (and C++/CLI code) to C# if the C++ code is pure managed. If it is not -- i.e. if there is native code included in the sources -- tools like .NET Reflector won't be able to translate the code for you.
If you do have native C++ code mixed in, then I'd recommend trying to move the native code into a separate DLL, replace your calls to DLL functions by easily identifiable stub functions, compile your project as a pure .NET library, then use .NET reflector to de-compile into C# code. Then you can replace the calls to the stub functions by p-invoke calls to your native DLL.
Good luck! I feel for you!
.NET Managed C++ is like a train wreck. But have you looked into C++ CLI? I think Microsoft did a great job in this field to make C++ a first class .NET citizen.
http://msdn.microsoft.com/en-us/magazine/cc163852.aspx
I'm not sure if this will work, but try using .Net Reflector along with ReflectionEmitLanguage plug-in. The RelelectionEmitLanguage plug-in claims to convert your assembly to c# code.
It has to be done manually unfortunately, but if the code is mostly C++/CLI (not native C++) then it can actually be done pretty quickly. I managed to port around 250,000 lines of C++/CLI code into C# in less than a couple of months, and I don't even know C++ very well at all.
If preserving Git history is important, you might want to git mv your cpp file into a cs file, commit, then start porting. The reason for this is that Git will think your file is new if you modify it too much after renaming it.
This was my approach when porting large amounts of code (so that it wouldn't take forever):
Create another worktree / clone of the branch and keep it open at all times
This is extremely important as you will want to compare your C# to the old C++/CLI code
Rename cpp to cs, delete header file, commit
I chose to rename the cpp file since its git history is probably more important than the header file
Create namespace + class in cs file, add any base classes/interfaces (if abstract sealed, make static in C#)
Copy fields first, then constructors, then properties, and finally functions
Start replacing with Ctrl+H:
^ to empty
:: to .
-> to .
nullptr to null
for each to foreach
gcnew to new
L" to "
Turn on case sensitivity to avoid accidental renames (for example L"cool" should become "cool", not "coo"
Prefixes like ClassName:: to empty, so that MyClass::MyMethod becomes MyMethod
Go through the red code and port manually code that cannot be just replaced (e.g. some special C++ casts), unless you have some cool regex to do it fast
Once code compiles, go through it again, compare to C++/CLI line by line, check for errors, clean it up, move on.
If you encounter a dependency that needs to be ported, you could pause, port that, then come back. I did that, but it might not be so easy.
Properties were the most annoying to port, because I had to remove everything before and after the getters and setters. I could have maybe written a regex for it but didn't bother doing so.
Once the porting is done, it's very important that you go through the changes line by line, read the code, and compare with C++/CLI code and fix possible errors.
One problem with this approach is that you can introduce bugs in variable declarations, because in C++/CLI you can declare variables in 2 ways:
MyType^ variable; <- null
MyType variable; <- calls default constructor
In the latter case, you want to actually do MyType variable = new MyType(); but since you already removed all the ^ you have to just manually check and test which one is correct. You could of course just replace all ^'s manually, but for me it would have taken too long (plus laziness) so I just did it this way.
Other recommendations:
Have a dummy C++/CLI project and a tool like LinqPad or another C# project to test differences between C++/CLI and C# if you're unsure of a piece of ported code
Install Match Margin to help highlight similar code (helped me when porting WinForms code)
ReSharper! It helped with finding bugs and cleaning up the code a LOT. Truly worth the money.
Some gotchas that I encountered while porting:
Base classes can be called in C++/CLI like so: BaseClass->DoStuff, but in C# you would have to do base.DoStuff instead.
C++/CLI allows such statements: if (foo), but in C# this has to be explicit. In the case of integers, it would be if (foo != 0) or for objects if (foo != null).
Events in base classes can be invoked in C++/CLI, but in C# it's not possible. The solution is to create a method, like OnSomeEvent, in the base class, and inside that to invoke the event.
C++/CLI automatically generates null checks for event invocations, so in C# make sure to add an explicit null check: MyEvent?.Invoke(this, EventArgs.Empty);. Notice the question mark.
dynamic_cast is equivalent to as cast in C#, the rest can be direct casts ((int) something).
gcnew can be done without parentheses. In C# you must have them with new.
Pay attention to virtual override keywords in the header files, you can easily forget to mark the C# methods with override keyword.
Intefaces can have implementations! In this case, you might have to rethink the architecture a bit. One option is to pull the implementation into an abstract class and derive from it
Careful when replacing casts with Convert calls in C#
Convert.ToInt32 rounds to the narest int, but casting always rounds down, so in this case we should not use the converter.
Always try casting first, and if that doesn't work, use the Convert class.
Variables in C++/CLI can be re-declared in a local scope, but in C# you get naming conflicts. Code like this easily lead to hard to find bugs if not ported carefully.
Example: An event handler can take a parameter e, but also has a try-catch like catch (Exception e) which means there are 2 e variables.
Another example:
// number is 2
int number = 2;
for (int number = 0; number < 5; number++)
{
// number is now 0, and goes up to 4
}
// number is again 2!
The above code is illegal in C#, because there is a naming conflict. Find out exactly how the code works in C++ and port it with the exact same logic, and obviously use different variable names.
In C++/CLI, it's possible to just write throw; which would create a generic C++ exception SEHException. Just replace it with a proper exception.
Be careful when porting code that uses the reference % sign, that usually means that you will have to use ref or out keywords in C#.
Similarly, pay attention to pointers * and & references. You might have to write additional code to write changes back whereas in C++ you can just modify the data pointed to by the pointer.
It's possible to call methods on null object instances in C++/CLI. Yes seriously. So inside the function you could do If (this == null) { return; }.
Port this type of code carefully. You might have to create an extension method that wraps over this type of method in order to avoid breaking the code.
Check and make sure everything in the old project file vcxproj was ported correctly. Did you miss any embedded resources?
Careful when porting directives like #ifdef, the "if not" (#ifndef) looks awfully similar but can have disastrous consequences.
C++/CLI classes automatically implement IDisposable when adding a destructor, so in C# you'll need to either implement that interface or override the Dispose method if it's available in the base class.
Other tips:
If you need to call Win32 functions, just use P/Invoke instead of creating a C++/CLI wrapper
For complex native C++ code, better create a C++/CLI project with managed wrappers
Again, pay attention to pointers. I had forgotten to do Marshal.StructureToPtr in my P/Invoke code which wasn't necessary in the C++ version since we had the actual pointer and not a copy of its data.
I have surely missed some things, but hopefully these tips will be of some help to people who are demoralized by the amount of code that needs to be ported, especially in a short period of time :)
After porting is done, use VS/ReSharper to refactor and clean up the code. Not only is it nice for readability, which is my top priority when writing code, but it also forces you to interact with the code and possibly find bugs that you otherwise would have missed.
Oh and one final FYI that could save you headaches: If you create a C++/CLI wrapper that exposes the native C++ pointer, and need to use that pointer in an external C++/CLI assembly, you MUST make the native type public by using #pragma make_public or else you'll get linker errors:
// put this at the top of the wrapper class, after includes
#pragma make_public(SomeNamespace::NativeCppClass)
If you find a bug in the C++/CLI code, keep it. You want to port the code, not fix the code, so keep things in scope!
For those wondering, we got maybe around 10 regressions after the port. Half were mistakes because I was already on autopilot mode and didn't pay attention to what I was doing.
Happy porting!
Back ~2004 Microsoft did have a tool that would convert managed C++ to C++/CLI ... sort of. We ran it on a couple of projects, but to be honest the amount of work left cleaning up the project was no less than the amount of work it would have been to do the conversion by hand in the first place. I don't think the tool ever made it out into a public release though (maybe for this reason).
I don't know which version of Visual Studio you are using, but we have managed C++ code that will not compile with Visual Studio 2005/2008 using the /clr:oldSyntax switch and we still have a relic VS 2003 around for it.
I don't know of any way of going from C++ to C# in a useful way ... you could try round tripping it through reflector :)
Such projects are often done in c++/cli because C# isn't really an elegant option for the task. e.g. if you have to interface with some native C++ libraries, or do very high performance stuff in low level C. So just make sure whoever chose c++/cli didn't have a good reason to do it before doing the switch.
Having said that, I'm highly skeptical there's something that does what you ask, for the simple reason that not all C++/cli code is translatable to C# (and probably vice versa too).