C / C++ / MFC

19-Nov-07 22:11

Again, thanks for your time and help.

Beginner

john563219-Nov-07 2:09

john5632

19-Nov-07 2:09

Hi Experts,
I am new in VC++.Please suggest me some books to get trained in vc++.

Kerem Guemruekcue19-Nov-07 2:40

Kerem Guemruekcue

19-Nov-07 2:40

Hi,

there are tons of free material on the www, but if you like
some "paper" then i can recommend some books from MSPress,
which i consider to be the best available (beside the original
MSDN Libary which is also for free!). Its up to you whether you
want to read the MSDN Libary or want to spend a lot of money
for some books that will be outdated in a short time (view years
in common).

Go here and search with C++ inside the Web Document:
http://www.microsoft.com/mspress/findabook/list/title.aspx[^]

---------
Beste Grüsse / Best regards / Votre bien devoue

Kerem Gümrükcü
kerem.g@arcor.de

Best Quote: "Ain't nobody a badass with a double dose
of rock salt...", Kill Bill Vol.2

Microsoft Live Space: http://kerem-g.spaces.live.com/
Latest Open-Source Projects
Tools and Software: http://entwicklung.junetz.de
Sign my guestbook: http://entwicklung.junetz.de/guestbook/
-----------------------
"This reply is provided as is, without warranty express or implied."

Johpoke19-Nov-07 2:44

Johpoke

19-Nov-07 2:44

I liked "Sam's Teach Yourself Visual C++ in 21 Days", it starts of easy and teaches you relevant things.

//Johannes

chandu00419-Nov-07 3:02

chandu004

19-Nov-07 3:02

13 essential skills in vc++ by steven holzner.

How do I call an instance method from an exported method in a MFC DLL?

Hamid_RT19-Nov-07 3:48

Hamid_RT

19-Nov-07 3:48

On the net see www.cplusplus.com[^] and also codeproject has good articles.

arnold_w19-Nov-07 0:24

Re: How do I call an instance method from an exported method in a MFC DLL?

19-Nov-07 0:24

I have created a dll in MFC using the Visual Studio wizard and the dll exports a function called MyExportedMethod:

#include "stdafx.h"
#include "DllProblem.h"

BEGIN_MESSAGE_MAP(CDllProblemApp, CWinApp)
END_MESSAGE_MAP()

CDllProblemApp::CDllProblemApp()
{
}

CDllProblemApp theApp;

BOOL CDllProblemApp::InitInstance()
{
CWinApp::InitInstance();
return TRUE;
}

double _stdcall MyExportedMethod(double param)
{
// Here I would like to call the
// MethodIwouldLikeToInvoke method in class MyClass.
// How do I do that???

return 0;
}

I would like the MyExportedMethod method to invoke a (non-static) method in a class called MyClass:

#include "stdafx.h"
#include "DllProblem.h"
#include "MyClass.h"

IMPLEMENT_DYNAMIC(MyClass, CDialog)

MyClass::MyClass(CWnd* pParent /*=NULL*/): CDialog(MyClass::IDD, pParent)
{
}

MyClass::~MyClass()
{
}

void MyClass::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
}

BEGIN_MESSAGE_MAP(MyClass, CDialog)
END_MESSAGE_MAP()

void MyClass::MethodIwouldLikeToInvoke()
{
MessageBox(L"Congratulations! The exported method successfully invoked the correct method!");
}

What should I add to successfully invoke the MethodIwouldLikeToInvoke from the MyExportedMethod method? This may seem like a simple problem and that is ok, this is not a trick question (I'm a beginner C++ programmer). Thank you in advance!

Matthew Faithfull19-Nov-07 0:32

Re: How do I call an instance method from an exported method in a MFC DLL?

19-Nov-07 0:32

To call a non-stati cinstance method what you need is an instance. You could an a MyClass as a member of CDllProblemApp then you have one once the application object is constructed.

<br />
<br />
class CDllProblemApp...<br />
{<br />
...<br />
MyClass myInstance;<br />
...<br />
};<br />
<br />
<br />
double _stdcall MyExportedMethod(double param)<br />
{<br />
  theApp.myInstance.MethodIwouldLikeToInvoke();<br />
  return 0;<br />
}<br />
<br />

or you could just create a stack based local instance

<br />
double _stdcall MyExportedMethod(double param)<br />
{<br />
  MyClass anInstance;<br />
  anInstance.MethodIwouldLikeToInvoke();<br />
  return 0;<br />
}<br />

depending on what you want it for. Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

arnold_w19-Nov-07 1:02

Re: How do I call an instance method from an exported method in a MFC DLL?

19-Nov-07 1:02

Thanks for your suggestions, however, I can't get them to work. In both cases I get Debug Assertion Failed from the application that calls the dll (Microsoft Excel). The strange thing is that the following works perfectly:

BOOL CDllProblemApp::InitInstance()
{
CWinApp::InitInstance();
MyClass anInstance;
anInstance.MethodIwouldLikeToInvoke();
return TRUE;
}

but if I place the code in MyExportedMethod I get the Debug Assertion:

double _stdcall MyExportedMethod(double param)
{
MyClass anInstance;
anInstance.MethodIwouldLikeToInvoke(); // THIS LINE GENERATES DEBUG ASSERTION!!!
return 0;
}

Please note that MyExportedMethod is not part of the class CDllProblemApp. Should it be? If so, how do I export that method?

Matthew Faithfull19-Nov-07 1:07

Re: How do I call an instance method from an exported method in a MFC DLL?

19-Nov-07 1:07

??That doesn't sound right. What exactly does the Debug Assertion say. Is is occuring in MethodIwouldLikeToInvoke? I guess it must be. In which case you have another problem, your call is working but something else is not.

To export a class member function it must be public and you will need to export the class itself. For an example of how to do this generate a new Dll with the VS2005 Wizard and choose 'Exports Some Symbols'. That will give you a commented example of how to do a variety of exports.

Nothing is exactly what it seems but everything with seems can be unpicked.

arnold_w19-Nov-07 2:09

19-Nov-07 2:09

Yes, it is occuring in MethodIwouldLikeToInvoke, there's something wrong with my MessageBox statement. If I put some other code in the MethodIwouldLikeToInvoke, it is executed properly. I still have a problem left, but I will start a new thread for that issue. Thanks a lot for your help!

About Socket Buffer

manish.patel19-Nov-07 0:12

manish.patel

19-Nov-07 0:12

How can we know that the buffer of the Socket is full or not?

Anyone Please provide help.

Thanks and Regards,
Manish Patel.
B.E. - Information Technology.

Matthew Faithfull19-Nov-07 0:36

19-Nov-07 0:36

In my experience you know when a socket buffer is full because things start to go badly wrong. A full socket buffer is not something you want to be waiting around for or in fact ever see. Best to avoid it if you can. Filling socket buffers on Win9x will frequently take down the whole operating system and the process on Windows NT. The fact that it took MS 3 versions of Windows to stop this being a total disaster area tells you all you need to know. Don't go there Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

manish.patel19-Nov-07 0:50

manish.patel

19-Nov-07 0:50

But i want to stop sending messages when buffer gets full because when buffer gets full client closes the connection.

Any idea?

Thanks in advance

Manish Patel.
B.E. - Information Technology.

Matthew Faithfull19-Nov-07 1:03

19-Nov-07 1:03

My point is that you need to stop sending messages BEFORE the buffer gets full because once it's full it's too late, data is already corrupt and the connection drops. Ultimately the only reliable way I've found to do this is to make sure that your client reads messages faster than your server sends them so the buffer never fills up. The client should probably have a dedicated thread or threads servicing the socket connection and placing the messages recieved into a queue in memory that you control. If the queue gets too long the client will need to tell the server or find some other way to cope.
Your server will ultimately be talking to more than one client right? over a limited speed network, so there's no reason your client can't keep up with the traffic your server can send it as long as it can handle the full network bandwidth. On average it will only need to handle a tiny fraction of this as the bandwidth is shared.

Nothing is exactly what it seems but everything with seems can be unpicked.

manish.patel19-Nov-07 1:10

manish.patel

19-Nov-07 1:10

Thats true but my client is flash and it automatically sending and recieving messages.

So i cant control client. So let me is there any way by which i can come to know that buffer can accept only some amount of packets.

Is it possible??

Manish Patel.
B.E. - Information Technology.

Matthew Faithfull19-Nov-07 1:22

19-Nov-07 1:22

Only if there is some indication within the protocol that Flash is using. Does it send acknowledgements? You could count the mismatch between messages sent and acks recieved and see what the limit is before Flash goes Bang. Then stop sending whenever you've sent x number more messages than you've had acks for. This will require a bit of trial and error to get right, keeping track of messages sizes etc. Other people must have had this problem with Flash. You could look for a Flash specific forum where you might get better help. I'm afarid I've never used Flash or written a socket server app against an exisitng 3rd party black box client. Good luck Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.

Mark Salsbery19-Nov-07 6:36

Mark Salsbery

19-Nov-07 6:36

You know you're getting ahead when send() returns less bytes sent than you
requested to be sent (it may even return 0 if the send buffer is completely full!).

You should always be checking the return value so you can resend unsent bytes.

Mark

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

Mark Salsbery19-Nov-07 6:40

Mark Salsbery

19-Nov-07 6:40

Matthew Faithfull wrote:
A full socket buffer is not something you want to be waiting around for or in fact ever see.

What?

Do you have a link?

I've been overstuffing stuffing sockets since before Win95 and I've NEVER heard anything like that.
If you ignore unsent bytes then chances are real good that the app-layer protocol is going to be f*cked
but I've never heard of a problem below the app layer of the protocol stack.

Mark

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

Matthew Faithfull19-Nov-07 8:14

19-Nov-07 8:14

It's not sending but recieving buffers that are the problem. If you don't read from an open socket rapidly enough the recieving buffer fills up and the results are Mad | :mad:

That's my experience, no links I'm afraid but at least 2 of the fixes in MFC sockets are down to errors I (among other no doubt) reported way back last century when I was having said problems Smile | :)

Nothing is exactly what it seems but everything with seems can be unpicked.