Managed C++/CLI

Re: Copying array values into a managed structure

30-Mar-06 1:45

Hi,

basically the BitConverterClass should meet your requirements. But most likely there is a more elegant way to do this.

e.g.

structExample^ strEx = gcnew structExample();

strEx->a = BitConverter::ToInt32(byteArray,indexofyourinteger);

regards Tobias

Sangeetha.R30-Mar-06 18:18

Re: Copying array values into a managed structure

30-Mar-06 18:18

I need to copy the array elements into the structure on a whole at a stretch as "memcpy()" does in ummanaged code, since I do have 100 elements/members in the structure.

2bee 30-Mar-06 19:31

Checking For Null while rasing the events

30-Mar-06 19:31

Well you can either use serialize/deserialize on your struct or you could actually use one of these methods:

Marshal::PtrToStructure(...);<br />
Marshal::StructureToPtr(...);

Please note that those methods marshal data from a managed object to an unmanaged block of memory and vice versa. Further information is also provided here:

http://www.dotnet247.com/247reference/msgs/57/289239.aspx[^]

regards Tobias

Sangeetha.R30-Mar-06 0:03

30-Mar-06 0:03

Hi,

I want to raise an event from my code in vc++.
while raising the event i need to check for the null.
Basically to know whether some one has registered for this event . How the event can be checked for the Null value.
if it is not checked System::NullReference Exception is thrown

thanks in advance,
Sangeetha

Milton Karimbekallil30-Mar-06 4:08

Milton Karimbekallil

30-Mar-06 4:08

try if ( event == nullptr )

rgds...mil10.

Sangeetha.R30-Mar-06 21:18

30-Mar-06 21:18

This gives the error as follows
error C3918: usage requires 'event' to be a data member

Regards
Sangeetha

Milton Karimbekallil31-Mar-06 1:54

Milton Karimbekallil

31-Mar-06 1:54

seems u have no declared the evenet object properly. Please post the code.

rgds...mil10.

2bee 31-Mar-06 3:17

31-Mar-06 3:17

Hi,

i discovered a while ago the same error and found this here quite useful:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=3059&SiteID=1[^]

Basically this behaviour is by design and a check for null is not neccessary. However, here is another explanation why.

http://lab.msdn.microsoft.com/productfeedback/viewfeedback.aspx?feedbackid=ac4f8e6b-c5eb-4ad0-9585-2fd0542a06aa[^]

regards Tobias

Sangeetha.R2-Apr-06 18:44

2-Apr-06 18:44

Here is the sample explaining why i need to check for a null.

Example:

public void delegate MyEventHandler();

public ref class MyClass
{
int i = 0;
public event MyEventHandler ^ MyEvent;

public SampleFunction
{
if(MyEvent!= nullptr) //raises C3918
{
MyEvent();
}
else
{
throw exp;
}
}
}
NOTE : I do register this event in some other class on certain conditions . So if it is not registered i need to throw it as a exception.
So it would be beeter if i check it for a null.
How can be this be done

Regards
Sangeetha

-- modified at 1:05 Monday 3rd April, 2006

2bee 2-Apr-06 20:13

Re: Checking For Null...a different approach

2-Apr-06 20:13

hi,

As mentioned in those forums, it is impossible to check an event against nullptr in c++/cli but you could actually use a public delegate as data member instead.

regards Tobias

2bee 4-Apr-06 0:58

System::DateTime HELP Please

4-Apr-06 0:58

Hi,

immediately after telling you to use a delegate i found myself confronted with a similar problem.
Though i had to find a solution for myself as well. Basically in my case, i need to check a remote event for any dead delegates which are still connected to it. Otherwise it will end up in a remoting exception each time i'll raise the event. So i did the following:

public delegate void SensorUpdatedEventHandler (Object^, UpdateEventArgs^);
 
public ref class SensorWebLink : ...
{
  ...
 
  SensorWeblink()
  {
    _RemotelyInvokedDelegates = nullptr;
  }
 
  ...
  ...
 
  private:
 
   static  SensorUpdatedEventHandler^  _RemotelyInvokedDelegates;
  
  public:		
		
    event SensorUpdatedEventHandler^  SensorUpdatedEvent
    {		
      void add(SensorUpdatedEventHandler^ pDelegate) 
      {
        _RemotelyInvokedDelegates += pDelegate;
      }
 
     void remove(SensorUpdatedEventHandler^ pDelegate) 
     {
       _RemotelyInvokedDelegates -= pDelegate;
     }
 
     void raise(Object^ pObject, UpdateEventArgs^ pEvtArgs) 
     {
       if (_RemotelyInvokedDelegates) 
       {
         _RemotelyInvokedDelegates->Invoke(pObject, pEvtArgs);
       }
     }
   };
 
   void RaiseSensorUpdatedEvent (UpdateEventArgs^ pEvtArgs);
};
  
// now i can easily access the invocation list
  
void SensorWebLink::RaiseSensorUpdatedEvent(UpdateEventArgs^ pEvtArgs)
{
  if(_RemotelyInvokedDelegates == nullptr)
  {
    Console::WriteLine("No listeners");
  }
  else
  {
    Console::WriteLine("Number of Listeners: {0}",_RemotelyInvokedDelegates->GetInvocationList()->Length);
    SensorUpdatedEventHandler^ temporaryHandler = nullptr; 
     
    for each( Delegate^ del in _RemotelyInvokedDelegates->GetInvocationList())
    {
       try
       {
         temporaryHandler = (SensorUpdatedEventHandler^) del;
         temporaryHandler(this, pEvtArgs);
       }
       catch( Exception^ e )
       {
         Console::WriteLine( e->ToString() );
         _RemotelyInvokedDelegates -= temporaryHandler;
       }
    }
  }
}

Btw. I had this idea after reading this msdn article:

http://msdn2.microsoft.com/en-US/library/5f3csfsa(VS.80).aspx[^]

cheers Tobias

Uniscribe woes...

Super Lloyd29-Mar-06 13:05

Super Lloyd

29-Mar-06 13:05

er... it's a kind of programing question but I though of asking it here as no one know the answer to this question out of all mainstream categories anyway....

I wrote a ManagedC++/.NET wrapper around Uniscribe. Which is the lowest level international text rendering (win32) API as I understand it.
With it I'm able to do custom rendering of formatted international text.
That's all good.
(For the curious who don't know it, you use various ScriptXXX to perform text analysis and then you finally render 'glyphs' (as opposed to characters) with ScriptTextOut)

Now come the problem, when I try to print.
I even manage to achieve perfect WYZIWIG behavior, that's cool and it works well on my work computer, on many customer's computer, on my home computer.

BUT, for some customer the preview is completely blank.
And for some other the printed page is completely blank as well.

What could it be?
How to fix that?
Any ideas?
Yep I have already (and unsuccessfuly) tried news://news.microsoft.com/microsoft.public.win32.programmer.international

-- modified at 23:31 Wednesday 29th March, 2006

Re: Uniscribe woes...

George L. Jackson29-Mar-06 17:49

George L. Jackson

29-Mar-06 17:49

I don't know much about what you are doing. However, I have had the same problem but it may or may not be related to yours. You may need to check the installed fonts. If the computer/printer cannot properly substitute your run-time font, a lot of times it just prints a blank page.

Re: Uniscribe woes...

Super Lloyd29-Mar-06 17:57

Super Lloyd

29-Mar-06 17:57

I should know... (the analysis function should tell me!)
Anyway that gave some related and unrelated idea... I'll try, thanks for the tip!

Saber00129-Mar-06 2:25

Saber001

29-Mar-06 2:25

I'm trying to save the Time to the [char templog[256]]
it works perfectly on the developer pc. problem comes when running on client pc.

sprintf( templog, "\t%s ->Now Playing MP3::%s",<br />
	 DateTime::Now.ToString( L"T" ), advert );

output after saving to text file developer pc:

15:19:26 ->Now Playing MP3::C:\Media\MP3\Mike & The Mechanics - Word Of Mouth.mp3

output after saving to text file client pc:

È%¹y ->Now Playing MP3::C:\Media\MP3\Mike & The Mechanics - Word Of Mouth.mp3

both have .net 1.1 and .net 2.0 framework installed
both running Windows XP Home
both time & Date settings equal (including format settings)

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

code written in visual c++ .net 2003 Std edition.

any hints or help would be great thx in advance

dewald@silversquare.co.za

Re: System::DateTime HELP Please

2bee 29-Mar-06 11:19

Re: System::DateTime HELP Please

29-Mar-06 11:19

Hi Saber,

unfortunately I can't tell you, what is actually causing that behavior but I would start investigating in the following order:

1. try to use

sprintf( templog, "\t%s ->Now Playing MP3::%s",
DateTime::Now.ToString( L"T", DateTimeFormatInfo.InvariantInfo), advert );

and check also for any Globalization issues?, CultureInfo... etc.

2. check your character set or any formatting / encoding

3. give swprintf(...) a try

Hope that helps. Anyway it would be great if you could publish your result.

best regards

Tobias

Saber00130-Mar-06 2:31

Saber001

30-Mar-06 2:31

Thx for the advice,

char tempbuf[128];<br />
sprintf( templog, "\t%s ->Now Playing FullScreen::%s::%s", <br />
         _strtime(tmpbuf));

some times its better to stick to the basics. I've even checked the value
on client pc with gamehack the date works (also in log file) but the time is
giving problems.

_strtime(tmpbuf); is quicker and eisier to use any way...

thanx again for helping...

Re: System::DateTime HELP Please

George L. Jackson29-Mar-06 17:15

George L. Jackson

29-Mar-06 17:15

I see a couple problems with your code. First of all, "DateTime::Now.ToString( L"T" )" returns a Unicode string and sprintf does not handle Unicode. Secondly, you need to marshal or "pin" the managed heap string. The managed heap string can move without warning.

-- modified at 23:15 Wednesday 29th March, 2006

About delete in Managed C++

Bob_Sun28-Mar-06 18:34

Bob_Sun

28-Mar-06 18:34

I have an app that works the following way:

1.the main process is written in C#
2.the main process uses class witten in Managed C++
3.in classes wirtten in Managed C++, Unmanaged C libs are called
4.as well the main process communicate with other host via .NET remoting

The other day a got a socket exception says (this happens at a very low frequency):
"An operation was attempted on something that is not a socket"

I investegated a lot and come to know this will only happen when the TCP/IP stack is destroyed
(IP addresses are all fixed)

I don't think TCP/IP stack can be destroyed by codes in C#. In Managed C++, all object reference created on C#'s side were

<br />
    delete objRefCreatedInCSharp;<br />

in Dispose(). I am told this was done to prevent memory leak.

My qusetion is
1. Is delete necessary to prevent memory leak?
2. Won't this delete destroy TCP/IP stack at a certain timing?

Thank you very much.

-- modified at 0:35 Wednesday 29th March, 2006

Re: About delete in Managed C++

George L. Jackson29-Mar-06 17:21

George L. Jackson

29-Mar-06 17:21

You only use "delete" when you want to manually mark an object ready for disposal by the GC. If you prematurely use delete, of course, your code will not run properly. Since you did not provide any code examples, it is difficult to determine what your problem is.

Simple question about header files

Virtek27-Mar-06 8:49

Virtek

27-Mar-06 8:49

I've got two header files:

// This is file1.h

#include "file2.h"

__gc class Class1
{
....
};

// This is file2.h

#include "file2.h"

__gc class Class2
{
....
}

I want both files to "know" each other, but it becomes an endless loop when i try to #include
each other... Any idia ?

Thanks

Correction

Virtek27-Mar-06 8:51

Virtek

27-Mar-06 8:51

Correction about the file2.h file:

#include "file1.h"

of-course

Re: Correction

mcljava27-Mar-06 9:58

mcljava

27-Mar-06 9:58

Fundamental to the header files is the preprocessor. In order to avoid Multi-Inclusion you need a to tell the preprocessor to only include the header under certain conditions.

For example,

file1.h

<br />
#ifndef __FILE_1_H__<br />
#define __FILE_1_H__<br />
...<br />
#endif<br />

Now with that said, you probably need to revisit your header file design because you should not have a situation where File1 is including File2 and visa versa. If there is common definitions or structures, put those in a separate header. Keep the module specific data in the header that applies to the .CPP or .C module. You application might then look like:

file1.h

<br />
#include "File1.h"<br />
#include "CommonData.h"<br />
...<br />

file2.h would be similar.

Good Luck

Mike Luster
CTI/IVR/Telephony SME

Re: Simple question about header files

2bee 27-Mar-06 9:48