Managed C++/CLI Discussion Boards

Re: BlowFish

Mark Salsbery15-Jul-08 6:27

Mark Salsbery

15-Jul-08 6:27

Native and .NET Interoperability (interop)

Calling Native Functions from Managed Code[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: BlowFish

Paul Conrad16-Jul-08 9:35

Paul Conrad

16-Jul-08 9:35

Xaria wrote:
wish to use BlowFish encryption for my project. How do I pass the value from the form textbox to the Blowfish Encrypt function?
The Blowfish algo is written in Classic C++, but the Form is in managed C++.

Why not just write a managed implementation of it. Can't be that hard.

"The clue train passed his station without stopping." - John Simmons / outlaw programmer

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

Re: BlowFish

Xaria16-Jul-08 20:46

Xaria

16-Jul-08 20:46

I am trying to do just that.
Thanks

MarshalAs UnmanagedType::LPStrunc trouble

Thees Ch. Winkler13-Jul-08 2:44

Thees Ch. Winkler

13-Jul-08 2:44

Hello,

I am trying to access the SHGetKnwonFolderPath function on Vista from NET and I get an exception:
My code looks the following:

[DllImport("shell32.dll")]
extern "C" int SHGetKnownFolderPath([MarshalAs(UnmanagedType::LPStruct)] Guid^ rfid, unsigned int dwFlags, IntPtr hToken, IntPtr ppszPath);

ref class KnownFolders
{
public:
  static const Guid^ AddNewPrograms = gcnew Guid( "de61d971-5ebc-4f02-a3a9-6c82895e5c04" );
... snip ...
};

When running the following code the runtime raises an exception that parameter #1 can not be marshaled as there is no layout information available

String^ str;
IntPtr path;

if(Shell32::SHGetKnownFolderPath((Guid^)KnownFolders::AddNewPrograms, 0, IntPtr::Zero, path) == 0)
{
		
	str = System::Runtime::InteropServices::Marshal::PtrToStringAuto(path);
	System::Runtime::InteropServices::Marshal::FreeCoTaskMem(path);
}

(

Re: MarshalAs UnmanagedType::LPStrunc trouble

Mark Salsbery13-Jul-08 16:08

Mark Salsbery

13-Jul-08 16:08

As the exception message indicates, without structure layout, the Guid can't be marshaled.

Using the info in "How to: Convert Between System::Guid and _GUID[^]", you could marshal
the Guid as a byte array, something like:

[DllImport("shell32.dll", CallingConvention = CallingConvention::Cdecl)]
extern int SHGetKnownFolderPath([MarshalAs(UnmanagedType::LPArray)] array<Byte> ^ar, UInt32 dwFlags, IntPtr hToken, [Runtime::InteropServices::Out] IntPtr %ppszPath);

...

String^ str;
IntPtr path;

array<Byte> ^ar = KnownFolders::AddNewPrograms->ToByteArray();
if(SHGetKnownFolderPath(ar, 0, IntPtr::Zero, path) == 0)
{
	str = System::Runtime::InteropServices::Marshal::PtrToStringAuto(path);
	System::Runtime::InteropServices::Marshal::FreeCoTaskMem(path);
}

Note I also changed the Path paramter so it would marshal as an Out parameter.
The "[Runtime::InteropServices::Out]" is optional - the "%" is NOT optional Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: MarshalAs UnmanagedType::LPStrunc trouble

Thees Ch. Winkler14-Jul-08 9:59

Thees Ch. Winkler

14-Jul-08 9:59

Thanks, that does the trick!

Smile | :)

Re: MarshalAs UnmanagedType::LPStrunc trouble

Mark Salsbery14-Jul-08 10:04

Mark Salsbery

14-Jul-08 10:04

Cool!

I forgot to mention - the "[MarshalAs(UnmanagedType::LPArray)]" is also
optional since that's the default marshaling behavior for the byte array handle.
I personally like seeing it there just so I know at a glance there's marshaling
going on for that parameter.

Also, the Environment::GetFolderPath Method[^] will get you common folder paths
without having to use interop.

Cheers,
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Calling .Net Interface from VC++

Debasis108-Jul-08 6:11

Debasis10

8-Jul-08 6:11

Just wondering whether you have ever required to call a .Net Interface/DLL from c++ code?
I could load the library, but can’t get the function pointer!

Would you have any suggestions?

typedef int (*cfunc)(void);

cfunc CreateFunction;

HINSTANCE hLib=LoadLibrary(sFullName.c_str());

CreateFunction = (cfunc) GetProcAddress((HMODULE)hLib, "iSquare");

Thanks,

Debasis

Re: Calling .Net Interface from VC++

Mark Salsbery8-Jul-08 6:57

Mark Salsbery

8-Jul-08 6:57

Debasis10 wrote:
call a .Net Interface/DLL from c++ code?

You can't from native c++ code. You can use C++/CLI, however, which is designed
to bridge the native/managed gap.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

How to give message from thread to main application in VC++.net?

AnayKulkarni7-Jul-08 21:27

AnayKulkarni

7-Jul-08 21:27

Hello to all,
I am having a .net application in which i am creating a thread which reads data from serial port.
I am having one buffer Buffer[1000] which store 1000 bytes data. Simultenously i have to display and store this data into one file. When buffer Size becomes 1000, i have to send message to main application form, to display this 1000 bytes data and also store it into a file.
I am having problem regarding how to send message to main application from a thread.I am facing this problem from last 10 days, but i am not geting proper solution.
Can anyone tell me please? It is urgent.

Thanks and Regards,

Abhijit

Re: How to give message from thread to main application in VC++.net?

killabyte7-Jul-08 22:05

killabyte

7-Jul-08 22:05

I would use pipes http://msdn.microsoft.com/en-us/library/aa365781(VS.85).aspx[^] but then again i am not up with the play on the latest .NET tools and tricks but "pipes" are tried n true easy solution to the messaging problem especially when u have to send data along with it.

otherwise if u dont need to send a chunk of data then u could simply use
PostMessage()/PostThreadMessage()

Re: How to give message from thread to main application in VC++.net?

LionAM8-Jul-08 0:22

LionAM

8-Jul-08 0:22

Hello!
You could use Invoke or BeginInvoke/EndInvoke to let
the main thread execute your delegate.
With Invoke, the worker thread waits until the handlers
have completed. There are examples in the msdn.

Alex

Can we reduce this function (x<-3 || x >3) further

pallaka7-Jul-08 20:18

pallaka

7-Jul-08 20:18

Can we reduce this function further in one simple statment as the compared number from -3 to +3 is same

Re: Can we reduce this function (x<-3 || x >3) further

LionAM8-Jul-08 0:35

LionAM

8-Jul-08 0:35

I don't think so.
(you could use abs(x) > 3, but I don't think it would be faster)

Re: Can we reduce this function (x<-3 || x >3) further

pallaka8-Jul-08 1:32

pallaka

8-Jul-08 1:32

Thanks for the reply but it is taking more CPU time than the given one.

Re: Can we reduce this function (x<-3 || x >3) further

killabyte8-Jul-08 2:07

killabyte

8-Jul-08 2:07

if u are worried about CPU time taken for such a simple operation then i would check the ASM output that is generated from the code, i think u will find that a number of C code options will boil down to the same ASM in the end.

What is the proper way to add a form to an existing class?

BuckBrown7-Jul-08 5:55

BuckBrown

7-Jul-08 5:55

Hi. I'm using Visual Studio C++/CLI. I have a well developed class that now has a need to have a user interface for it. Normally I will determine if I need a form associated with a class when I create the class, so the class is created as a System::Windows::Forms::Form. But now I have a class that I did not think would need a form associated with it so it was defined as a simple C++ ref class. What is the proper way to add a form to the class? Should I create a new UI Forms based class and cut and paste everything in my existing class into it? Or is there a simple way to instantiate a new form as a method of the existing class?

Thanks,
Buck

Re: What is the proper way to add a form to an existing class?

led mike7-Jul-08 6:16

led mike

7-Jul-08 6:16

BuckBrown wrote:
Normally I will determine if I need a form associated with a class when I create the class, so the class is created as a System::Windows::Forms::Form. But now I have a class that I did not think would need a form associated with it so it was defined as a simple C++ ref class. What is the proper way to add a form to the class? Should I create a new UI Forms based class and cut and paste everything in my existing class into it? Or is there a simple way to instantiate a new form as a method of the existing class?

Buck, what's up dude? Ever heard of Object Oriented Design Principles, Best Practices, Separation of Concerns, Design Patterns, Model-View-Controller?

Any of this ringing any bells with you? You don't tightly couple a "class" with the presentation layer of your design, it's not considered Best Practice and there are Patterns like MVC that represent solutions for this.

led mike

Re: What is the proper way to add a form to an existing class?

BuckBrown7-Jul-08 7:45

BuckBrown

7-Jul-08 7:45

Hi Mike,

Just so you know, I first learned programming using assembly on a state of the art Intel 8085 and our operating system was CP/M (that's what it was called before Microsoft bought it and renamed it MS-DOS). Over the years I have been forced to learn various programming languages on Data General, VAX, UNIX, and MS-DOS boxes, but all of the OO stuff was invented long after I got out of college. So the fact that I'm an over 50 microelectronics engineer with a EE degree and not a new Computer Science graduate, I can state with confidence that with the exception of Object Oriented Design Principles I've never heard of any of those terms before (nor whatever MVC means). You even mention a "presentation layer". I have never heard anyone use that term before. IO, User Interface, GUI sure, but "presentation layer"? I don't understand what you mean by "you don't tightly couple a class with the presentation layer". Visual Studio's forms designer seems to make things very tightly coupled. Anyways, if you could dumb down your responses for me that would be cool.

Thanks,
Old Buck

And my applications always work and do what they were designed to do.

Re: What is the proper way to add a form to an existing class?

led mike7-Jul-08 9:17

led mike

7-Jul-08 9:17

Hey Buck, sorry about that, I had no idea.

Most of those terms can be googled and wikipedia is a good introduction to most of them as well.

http://en.wikipedia.org/wiki/Separation_of_concerns[^]
http://www.google.com/search?hl=en&q=wikipedia+design+patterns&btnG=Search[^]
http://en.wikipedia.org/wiki/Model-view-controller[^]
http://en.wikipedia.org/wiki/Presentation_layer[^]
Prefer Loose Coupling[^]

If you are doing .NET development you should check out the Microsoft Patterns and Practices Center[^]

In OOD the simplest example of how to avoid tight coupling is if you have two classes that represent different things so there is no reason for them to "know" of each other, they have no relationship or association.

class A class B

Now you find a use model or activity for which the solution can use both of them. Bad Practice would be to modify either one or both to use them in combination resulting in a relationship or association. Best Practice would be to create a 3rd class that has a relationship to both the others and implements the solution combining the first two classes. This maintains the isolation between the first two classes.

class A           class B<br />
   \                /<br />
    \              /<br />
     \            /<br />
        class C<br />

led mike

Re: What is the proper way to add a form to an existing class?

killabyte7-Jul-08 23:37

killabyte

7-Jul-08 23:37

Easy way would just be to make a new form class and make the class a member of the new form class. ugly? yes. best practise? no. will it do the trick? probably Smile | :)

How can i create multiple instances of form

Xaria6-Jul-08 18:28

Xaria

6-Jul-08 18:28

How To create an array of form?

Re: How can i create multiple instances of form

Giorgi Dalakishvili6-Jul-08 21:44

Giorgi Dalakishvili

6-Jul-08 21:44

You create form array in the same way as you would create array of any other type.

Giorgi Dalakishvili

#region signature
my articles
#endregion

Bounded mouse position when moving child form

LionAM5-Jul-08 12:16

LionAM

5-Jul-08 12:16

Still another question:

I want to create a .NET equivalent to the MFC CDialogBar.
When I move a form which is a child of a panel,
the mouse position is bounded by the panel,
even if I set

Parent = nullptr;
TopLevel = true;

on first Move-Event and even if the panel is not
visible any more. Is there a workaround?

Alex

Re: Bounded mouse position when moving child form

LionAM6-Jul-08 6:26

LionAM

6-Jul-08 6:26

Hello!
For the mouse, I found a solution:
The allowed mouse position is bounded by the Cursor->Clip property.
But still the window can not be moved completely out of the panel,
it stops at the border.

Alex

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