C / C++ / MFC Discussion Boards

Re: got problem in compiling

led mike30-Oct-07 4:38

led mike

30-Oct-07 4:38

http://en.wikipedia.org/wiki/Pragma_once[^]

Re: got problem in compiling

David Crow30-Oct-07 4:39

David Crow

30-Oct-07 4:39

Since tmath.h, complex.h, and cmatrix.h are included multiples times, do you have safeguards in place to prevent multiple inclusions? Check out the #pragma once directive.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: got problem in compiling

led mike30-Oct-07 6:02

led mike

30-Oct-07 6:02

1hr 23mins ago
1hr 22mins ago

Poke tongue | ;-P

Re: got problem in compiling

Nelek30-Oct-07 22:04

Nelek

30-Oct-07 22:04

Another solution could be to make a new header file (i.e. Headers.h) or use the stdafx.h if you have it, to put all the #includes there.

By the way... #pragma once is the best option

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Help me to understand what I'm saying, and I'll explain it better to you

Wink | ;)

Naive Bayes

rarayi30-Oct-07 4:02

rarayi

30-Oct-07 4:02

Hi I need the source code of naive bayes classifier in C++ and I want to run it in VC++ in windows. Please help me.
thanks in advance

Re: Naive Bayes

Nelek30-Oct-07 4:09

Nelek

30-Oct-07 4:09

And I want a lottery winner ticket, can u find one for me? I don't mind is price is in euros or dollars Cool | :cool:

Re: Naive Bayes

led mike30-Oct-07 4:39

led mike

30-Oct-07 4:39

Read the post at the top of the forum titled "How to get an answer to your question". Pay attention to #2

how can i forbid anyone else to change the time of the computer?

lostangels30-Oct-07 3:37

lostangels

30-Oct-07 3:37

i have a computer that used by several people and i don't want anybody else to change the date and time of the computer, how can i do this through VC++?
thx.

Re: how can i forbid anyone else to change the time of the computer?

Nelek30-Oct-07 4:08

Nelek

30-Oct-07 4:08

I dont know, but I can imagine it with a hook, detecting when the Dialog to change date and time of the computer is being called and closing it.

Or saving the actual date and time in this moment and starting a time count somewhere. When that dialog is closed, asking for a password to save the changes, if password correct save changes, if not... restore the previously saved values + time offset.

It is just an idea that came when i read you. Most probably there are much better ways to do it.

Let us see what the masters say.

Re: how can i forbid anyone else to change the time of the computer?

led mike30-Oct-07 4:41

led mike

30-Oct-07 4:41

Make a User account for each person and restrict their privileges.

This is not a C++ answer, was it a C++ question? If not you are in the wrong forum

help needed for MFC ritch GUI controls

sarat12in30-Oct-07 3:28

sarat12in

30-Oct-07 3:28

hi all,

we are planning to change the look and feel of out product which is developed MFC classes with the help of our own classes as wrapers to MFC control classes to made the control look like flat control..
but on client requests we need to make controls look even more ritch like XP control.. with minimal changes

for that iwas looking at comancontrol6.0.. but comancontrol6.0 works only on windows XP.. but our product is well established on win2k server

please some one help me in finding out what the best solution for my problem mentioned abow

and also let me know how abt GDI+ , please let me know wether GDI+ works on win2k r no

am eagerly waiting for the suggessions from u
i hope u all will help me finding out the best solution for me

thank you

Re: help needed for MFC ritch GUI controls

Dewm Solo30-Oct-07 3:51

Dewm Solo

30-Oct-07 3:51

Well first of all GDI+ is part of the .Net framework 2.0. And indeed it works on Win2K, although since you cannot use XP's visual styles you will not be able to use them.

There is nothing stopping you from creating your own controls derived from the .Net controls and change their draw methods.

Dewm Solo - Managed C++ Developer

Re: help needed for MFC ritch GUI controls

led mike30-Oct-07 4:43

led mike

30-Oct-07 4:43

sarat12in wrote:
please let me know wether GDI+ works on win2k r no

They hide that information in the documentation[^]

send big message from client to server [modified]

Russell^'30-Oct-07 2:22

Russell^'

30-Oct-07 2:22

I have to send a file from client to server.
It's size is about 1MB.
I think that it is not a good idea to send it as a single message because it can be received corrupted. This because the CRC is computed on the entire message, so if there is a lot of noise the CRC can tell OK, but the file isn't rightly received. Am I right? Confused | :confused:

I think that I can split the file in short messages, so there the CRC check can work well.
But:
* How can I choose the right value of the size of the messages (30 bytes? 100 bytes? 1kbyte?)
* Can you also please suggest to me a way to check if the file is corrupted using an algorithm not based on CRC?

thanks all
Smile | :)

-- modified at 8:37 Tuesday 30th October, 2007

* I'm using winsock (but I'm not an expert Cry | :((

) (the trasmission is on a local ethernet network)
* I found a possible alternative algorithm of CRC to check the entire file at the end of trasmission: it is "RFC 1321" (or known as MD5). Does anyone used it before? It looks quite strong.

Russell

Re: send big message from client to server

JudyL_MD30-Oct-07 2:27

JudyL_MD

30-Oct-07 2:27

The size of your message pieces depends on your communication medium. You need to experiment and find the balance between transmission time and the overhead to prepare a message segment. Also, you'll need to implement some kind of handshake to handle corrupt message pieces.

If you're that concerned about corruption, do some investigating about Error Correcting Codes.

Judy

Re: send big message from client to server

Mark Salsbery30-Oct-07 7:15

Mark Salsbery

30-Oct-07 7:15

What protocol are you using?

If it's TCP, you don't need to worry about CRC.
You probably won't be able to send that much data in one
send() call though Smile | :)

Are you encrypting the data or just worried about successful delivery?

Mark

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

Re: send big message from client to server

Russell^'30-Oct-07 7:33

Russell^'

30-Oct-07 7:33

Thank you for you reply Big Grin | :-D

I'm using socket with TCP protocol.
I don't need to encript the data, my only problem is the success of this trasmission.
I know that usually at low level the data is cheched with CRC (as in TCP) ... but it works only on small frames (like 20/50 Bytes, not more, as my opinion).
I repeat that I'm not expert on Winsock, so I don't know if my message is splitted in more frames and then tranmitted. (do you know this? Confused | :confused:

)
To solve by myself the problem I was thinking to split the big message in more little messages. Then the only dubt is the length of the messages.
As you point send() function probally needs more shorter data (this probally is related on what I mean before)

Then, finally, when every little messages is received I have to check if the file is corrupted. But then I need an algorithm different from CRC (elseway probally this check will fail)...so....what use?
I found MD5, I like it Hmmm | :|

. Do you have any suggestions on this? Big Grin | :-D

thanks for your time

Russell

Re: send big message from client to server

Mark Salsbery30-Oct-07 8:03

Mark Salsbery

30-Oct-07 8:03

Russell' wrote:
I'm using socket with TCP protocol.
I don't need to encript the data, my only problem is the success of this trasmission.

Why worry about this then?

Yes, the TCP protocol will split your data into "frames". The network may further split those
frames. The protocol will also check for successful transmission, resend when necessary, etc. until all
data sent transmits successfully.

I'm not sure what you hope to gain by splitting into smaller units yourself.

I would let TCP do its thing. It's a very reliable protocol.

As for the send() function (and recv() as well), how much you can do at one time
depends on the socket's buffer size and how much room is left in that buffer.

Nothing changes at the application layer of the protocol stack however - you should always be
calling send() and recv() enough times until all data is sent or received.

When sending, for example (receiving is very similar)...

char *pNextByteToSend = ;
int nBytesToSend = ;

while (nBytesToSend > 0)
{
   int nBytesSent = ::send(socket, pNextByteToSend, nBytesToSend, 0); 

   if (SOCKET_ERROR == nBytesSent)
   {
      // error occurred
      int sockerr = ::WSAGetLastError();

      if (sockerr != WSAEWOULDBLOCK)
     {
         // handle error and exit while() loop
         break;
     }
   }

   pNextByteToSend += nBytesSent;
   nBytesToSend -= nBytesSent;
}

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

Re: send big message from client to server

Russell^'30-Oct-07 8:30

Russell^'

30-Oct-07 8:30

Great

Then you solved all my problems/dubts (I hope Unsure | :~

).
Thank you very very much
Rose | [Rose]

Russell

Re: send big message from client to server

Mark Salsbery30-Oct-07 8:06

Mark Salsbery

30-Oct-07 8:06

And yes you could use MD5 to check the integrity of the entire data sent.

That would be part of the application layer (your code) of your protocol,
not TCP Smile | :)

Mark

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

PC Controlled Relay Board

thes3cr3t130-Oct-07 2:06

thes3cr3t1

30-Oct-07 2:06

http://www.quasarelectronics.com/3165.htm[^]

Hey there,

Im relativly new to c++ and looking for a little advice,im interested in buying a PC Controlled Relay Board (Link above) that comes with its on software,however the website in question state's that it is possible to write your own software for the relayboard using a DLL from http://www.logix4u.cjb.net[^]now i have no experience in parralel port coding and was wondering how much of a mammoth task this would be.

Here is my concern - As you can see the board has 8 relays that can be independently controlled with software via the parralel port, Well how do i find the On/Off commands that will have to be called from my DLL and sent to the relay board to control each individual relay on the board?

Any advice would be greatly appriciated.
Thankyou for your time.
Chris

Re: PC Controlled Relay Board [modified]

Rhymhoont30-Oct-07 4:41

Rhymhoont

30-Oct-07 4:41

I don't have experience with that board you have listed but a while back I wrote a C program that controled 36 relays. In that case it was simple calls to functions supplied in the manufacturers' DLL. Basically I sent their function a bit pattern of the relay's I wanted on or off.

On initializing the app, you would set up the interface between the functions and the port / hardware. Just hope that their DLL si writen well.

I would have to go look in my files, but I seem to remember it was Houston Instruments or something. Not Texas Instruments.

In any case. the controling of the board from my code was the easiest part of the app.

-- modified at 10:52 Tuesday 30th October, 2007

I checked, it was National Intruments: http://www.ni.com

how to get Row count in MS flexgrid

panthal30-Oct-07 2:06

panthal

30-Oct-07 2:06

hi,
i'm using a flex grid in my project.
i don't know how to get the no of rows in the MS flexgrid

thanks
panthal

Re: how to get Row count in MS flexgrid

chandu00430-Oct-07 2:17

chandu004

30-Oct-07 2:17

yourgridvariable.GetRows();
will do for you.

--------------------------------------------
Suggestion to the members:
Please prefix your main thread subject with [SOLVED] if it is solved.
thanks.
chandu.

Re: how to get Row count in MS flexgrid[solved]

panthal30-Oct-07 3:24

panthal

30-Oct-07 3:24

thank u very much chandu,

i searched this function in more sites,

but i didn't get,
thank u

panthal

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