C# Discussion Boards - CodeProject

Problem solved

Ungi.4-Mar-04 20:15

Ungi.

4-Mar-04 20:15

I had to use SafeArrays as described in the msdn.

Datagrid Rows

Reinier van de Wetering1-Mar-04 19:13

Reinier van de Wetering

1-Mar-04 19:13

Is there a way to set the rows of a datagrid to disable row resize??

Method <Summary> descriptions

Reebop1-Mar-04 11:52

Reebop

1-Mar-04 11:52

They show up on the object browser, but not in code view (popup autofill thing) like the core ones. Something I'm doing wrong?

Re: Method <Summary> descriptions

Meysam Mahfouzi1-Mar-04 17:45

Meysam Mahfouzi

1-Mar-04 17:45

You have one project which has been compiled and now you are using it in another project. If you want to see the descriptions for methods and properties, you should just configure your first project before compiling it, so that it also generates the XML documentation file for you. It is, easy just right click on your solution and look for the configuration for xml documentation file. Supply a name for xml file and re-build your project. that is all!

Don't forget, that's

Persian Gulf

not Arabian gulf!

Murphy:
Click Here![^]

I'm thirsty like sun, more landless than wind...

Re: Method <Summary> descriptions

Heath Stewart1-Mar-04 18:15

Heath Stewart

1-Mar-04 18:15

m a y s a m wrote:
that is all!

Not quite. The XML doc has to be in the same directory as the assembly you want to reference (by path, not name).

Microsoft MVP, Visual C#
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Re: Method <Summary> descriptions

Meysam Mahfouzi1-Mar-04 18:17

Meysam Mahfouzi

1-Mar-04 18:17

That is all! Smile | :)

Don't forget, that's

Persian Gulf

not Arabian gulf!

Murphy:
Click Here![^]

I'm thirsty like sun, more landless than wind...

Re: Method <Summary> descriptions

Reebop1-Mar-04 22:32

Reebop

1-Mar-04 22:32

Thanks!

fog in opengl

shedid1-Mar-04 9:29

shedid

1-Mar-04 9:29

i'm new in programing opengl so.....
I'm heaving troubles implementing the fog function, is it possible for anyone to send me implementation for this function?

M Shedid

Re: fog in opengl

Nick Parker1-Mar-04 9:36

Nick Parker

1-Mar-04 9:36

Try reading 11.7 Other Atmospheric Effects[^] and then look at the Fog Comparison Demo[^] with included source.

- Nick Parker
My Blog

Re: fog in opengl

shedid4-Mar-04 6:55

shedid

4-Mar-04 6:55

thank you , but i want to use fog in a still image, not in animation, is it possible, as if i'm making a scene, so how may i do it? Smile | :)

Client Disconnected.

HAHAHA_NEXT1-Mar-04 8:39

HAHAHA_NEXT

1-Mar-04 8:39

IS there a way to know if the client is disconnected.

My server basically receives data from the client. It uses syncronous connection with a winodw timer (Thus avoiding completly teh multitreading issue.)

Re: Client Disconnected.

Heath Stewart1-Mar-04 9:21

Heath Stewart

1-Mar-04 9:21

This is a very ambiguous question. What client/server technology are you using? A simple TCP socket? .NET Remoting? Web Services? WebRequests? More information would be helpful.

Microsoft MVP, Visual C#
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Re: Client Disconnected.

HAHAHA_NEXT1-Mar-04 10:52

HAHAHA_NEXT

1-Mar-04 10:52

I am using simple TCP sockets.

Re: Client Disconnected.

Heath Stewart1-Mar-04 10:59

Heath Stewart

1-Mar-04 10:59

Then it depends greatly on your implementation. Some protocols - like DICT - will require that a client - if possible - send a QUIT message (or equivalent) for proper implementation. This tells the server that your client is disconnecting. Otherwise, when your server sends data you should catch any exceptions - which you should be doing anyway - and handle them appropriately. If you get a SocketException, for instance, check the SocketException.ErrorCode for WSAECONNRESET (10054) or WSAENOTCONN (10057). See the Windows Sockets V2 Error Codes[^] on MSDN for more information.

Microsoft MVP, Visual C#
My Articles

Re: Client Disconnected.

RNEELY2-Mar-04 6:38

RNEELY

2-Mar-04 6:38

Open a cmd prompt at your server and type:
netstat -a

Netstat then displays all connections and listening ports.

Check the Microsoft Windows 2000 Server Documentation on Command-line Utilities or type netstat /? for help.

Regards,
-Ron

Sincerely,
-Ron

ServicedComponent: How to tell you are in a transaction?

Le centriste1-Mar-04 8:29

Le centriste

1-Mar-04 8:29

I have a component that supports transactions. One of the method needs to know if it is within a transaction or not. Is there a way to know?

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: ServicedComponent: How to tell you are in a transaction?

Heath Stewart1-Mar-04 9:18

Heath Stewart

1-Mar-04 9:18

How about ContextUtil.IsInTransaction? There's other related methods for getting the transaction and its ID. Just see the .NET Framework SDK documentation for the System.EnterpriseServices namespace.

Microsoft MVP, Visual C#
My Articles

Re: ServicedComponent: How to tell you are in a transaction?

Le centriste1-Mar-04 9:24

Le centriste

1-Mar-04 9:24

Tx for the answer, exactly what I was looking for.

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Calling a third party DLL

Andy *M*1-Mar-04 8:28

Andy *M*

1-Mar-04 8:28

Hello,

I have a third party DLL that contains a create function, it creates an object in memory and returns a handle to it. When I am finished with it I can call a Destroy function with the handle to get rid of the object. While I am using the object each function the DLL has takes the handle to the object.

My question is: How do I write the DllImport stuff to get this handle properly?

I've tried:

[DllImport("tp.dll")]
internal static extern unsafe void* OpenFilter();

[DllImport("tp.dll")]
internal static extern unsafe void CloseFilter(void* handle);

[DllImport("tp.dll")]
internal static extern unsafe int IsOpen(void* handle);

and the same again with the void* replaced by IntPtr.

What am I doing wrong? If I write a test application in C I can use the DLL fine, but if I try the same in C# it doesn't work. Is there a problem with the way the third party DLL allocated its memory?

The third party DLL exposes C style functions and the same API as a C++ class (compatible with Visual C++ 6.0)

Any help would be much appreciated.

Cheers,
Andy.

Re: Calling a third party DLL

Nick Parker1-Mar-04 8:53

Nick Parker

1-Mar-04 8:53

Andy MacAngus wrote:
[DllImport("tp.dll")]internal static extern unsafe void* OpenFilter();[DllImport("tp.dll")]internal static extern unsafe void CloseFilter(void* handle);[DllImport("tp.dll")]internal static extern unsafe int IsOpen(void* handle);

Just a guess, but try:

[DllImport("tp.dll")]
public static extern IntPtr OpenFilter();
[DllImport("tp.dll")]
public static extern void CloseFilter(IntPtr handle);
[DllImport("tp.dll")]
public static extern int IsOpen(IntPtr handle);

- Nick Parker
My Blog

Re: Calling a third party DLL

Heath Stewart1-Mar-04 9:15

Heath Stewart

1-Mar-04 9:15

You never mentioned what the problem is. Since you're using C-style declarations, that clears-up one problem. Is this native DLL in a resolvable directory (i.e., current working directory or something in the %PATH%)? Are any exceptions thrown, and - if so - what exception (i.e., Type and text)?

Microsoft MVP, Visual C#
My Articles

Re: Calling a third party DLL

Andy *M*1-Mar-04 9:52

Andy *M*

1-Mar-04 9:52

Thanks for answering.

Yes, this is a native DLL - I believe it was written with Visual C/C++ 6.0 (the C++ part of it only works when linked with VC++6)

The DLL is in the same directory as the C# exe.

No exceptions are thrown. I think that the pointer that I am receiving back is not right but I don't know how to tell or not. If a native DLL allocates memory when being used in a managed application is there anything special I need to do? I've written a test application in C as well as the C# version and the test works in C - the code is virtually identical.

The symptom of the error is that when running in C# the IsOpen() function always returns false.

Re: Calling a third party DLL

Heath Stewart1-Mar-04 9:57

Heath Stewart

1-Mar-04 9:57

Andy MacAngus wrote:
If a native DLL allocates memory when being used in a managed application is there anything special I need to do?

It depends. Is the caller expected to free the memory? If so, you should use GlobalAlloc or CoTaskMem, which you can free with the Marshal class methods.

What is this a pointer to? If it's a pointer to a struct, for instance, you need to define that struct in managed code and you can use Marshal.PtrToStructure. Keep in mind your managed-unmanaged marshaling, too, which you can control with MarshalAsAttribute and knowledge of bit-lengths (like an int in unmanaged code should use UnmanagedType.SysInt since its bit-length is system-dependent, and a LONG and INT in unmanaged code are both an Int32 in managed code.

Note, from what I can tell, you don't need any unsafe code here. IntPtr will usually do what you need it to.

Microsoft MVP, Visual C#
My Articles

Re: Calling a third party DLL

Andy *M*1-Mar-04 10:09

Andy *M*

1-Mar-04 10:09

Hi,

The caller is not expected to do anything to allocate or deallocate memory. The OpenFilter() and CloseFilter() functions do that. They return a HANDLE (which is just a C-macro definition for void*) so it is a pointer to something I don't know much about it is all accessed through the API that the DLL exposes.

I tried using the IntPrr but I just get the same results. What is most fustrating is that I can see it working in C (all I am doing in my test is an open, test for is open then close)

Cheers,
Andy

Re: Calling a third party DLL

Heath Stewart1-Mar-04 10:46

Heath Stewart

1-Mar-04 10:46

Andy MacAngus wrote:
They return a HANDLE (which is just a C-macro definition for void*)

Thanks, I know! Smile | :)

I started programming on C many, many years ago. Still use it sometimes.

What you're doing isn't at all different from what MANY classes in the .NET base class library, do. Take controls in Windows Forms, for example - they all use window handles (HWNDs), as well as many other types of handles (all typedefs of the same thing, of course).

You mentioned that you're checking the return of IsOpen against a boolean expression. Are you comparing against true or false? Or are you equating the return against 0, 1, some negative number, etc? In the former case, you should declare your method return value as a bool, so long as the concept of a boolean in your unmanaged code uses 0 for false and anything else for true (like the BOOL typedef). You'd probably get compiler errors otherwise, but I honestly can't see the problem.

You're right to use an IntPtr for void*. Despite your return value, do you get a valid memory address? If you share these two projects in a simple solution (you'll have to upgrade the old VC++ 6 project, of course), you could actually debug projects and see what is happening in both managed and unmanaged code.

Microsoft MVP, Visual C#
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