Re: Experts help reg threads - C / C++ / MFC Discussion Boards

yanuart12-Apr-04 4:23

12-Apr-04 4:23

I get this linker error everytime I tried to create an instance of _variant_t,
I've check my project settings in case i miss any library.. but everything seems in order..
what did I miss ??

Re: _variant_t causing linker error

David Crow12-Apr-04 4:28

David Crow

12-Apr-04 4:28

yanuart wrote:
what did I miss ??

Telling us what the linker error is.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: _variant_t causing linker error

yanuart12-Apr-04 6:23

yanuart

12-Apr-04 6:23

oh, that's okay I just include comdef.h and everything's fine

creating name pipe

pnpfriend12-Apr-04 3:40

pnpfriend

12-Apr-04 3:40

I'm trying to create a clients/server program, which only one server and lots of clients..
so I get the computer name using GetComputerName( ) as a server name pipe.

I had no problem creating name pipe when
lpszPipename = "\\\\.\\pipe\\mynamepipe";

but when I changed lpszPipename, it doesn't work..
LPCTSTR lpszPipename = "\\\\computer1\\pipe\\mynamepipe";

<br />
//LPCTSTR lpszPipename = "\\\\.\\pipe\\mynamepipe";<br />
LPCTSTR lpszPipename = "\\\\computername\\pipe\\mynamepipe";<br />
<br />
HANDLE hPipe;<br />
<br />
hPipe = CreateNamedPipe( <br />
		   lpszPipename,             // pipe name <br />
		   PIPE_ACCESS_DUPLEX,       // read/write access <br />
		   PIPE_TYPE_MESSAGE |       // message type pipe <br />
		   PIPE_READMODE_MESSAGE |   // message-read mode <br />
		   PIPE_WAIT,                // blocking mode <br />
		   PIPE_UNLIMITED_INSTANCES, // max. instances  <br />
		   BUFSIZE,                  // output buffer size <br />
		   BUFSIZE,                  // input buffer size <br />
		   NMPWAIT_USE_DEFAULT_WAIT, // client time-out <br />
		   NULL);                    // no security attribute <br />
<br />
	   if (hPipe == INVALID_HANDLE_VALUE) <br />
	   {<br />
		   MessageBox("CreatePipe failed"); <br />
   		   return ;<br />
	   }<br />

What am I doing wrong?

Re: creating name pipe

GuimaSun12-Apr-04 7:51

GuimaSun

12-Apr-04 7:51

The MSDN says:

lpName
[in] Pointer to the null-terminated string that uniquely identifies the pipe. The string *MUST* have the following form:
\\.\pipe\pipename

I suggest you put your "computername" preceding the "pipename" name part.

GuimaSun
www.nexsun.com.br

Re: creating name pipe

pnpfriend13-Apr-04 7:47

pnpfriend

13-Apr-04 7:47

The problem is that both server.exe and client.exe are communicating very well if and only if they both are on the same machine.

For examplle. there are 3 machines, c1,c2,and c3.
The server.exe is running on c2 and the client is running on each machine.
(note: both server.exe and client.exe are on the network drive.)
only the client on c2 is communicating with the server because to the client is on the same machine that the server.exe is running.
the other clients on c1 and c3 are not able to communicate with the server.exe.

Namepipe is used to commnunication between client and server.

CreateNamepipe(), "\\\\.\\pipe\\c2", is used by server.
CreateFile(),"\\\\.\\pipe\\c2", is used by client.
ReadFile() and WriteFile() are used to communication between client and server.

I thought I have to change the string ""\\\\.\\pipe\\c2", to "\\\\c2\\pipe\\c2", so client can find the server and talk. but I cant' even createNamepipe using above string ("\\\\c2\\pipe\\c2")
If I used the old string "\\\\.\\pipe\\c2" then client on the other machine can't find server.

what am i missing?

Experts help reg threads

ykutanoor12-Apr-04 3:14

ykutanoor

12-Apr-04 3:14

I am doing a multi threaded application that involves exchange of data.
ONE UI THREAD
AND 3 WORKER THREADS.PLS LET ME HOW TO EXCHANGE THE DATA BETWEEN THESE 3 WORKER THREADS.
FOR EX:THE FIRST THREAD WILL GIVE THE SECOND THREAD THE 2 NUMBERS AS ARGUEMENTS.the second thread should return the first thread the sum.
Pls help

YKUT

Re: Experts help reg threads

David Crow12-Apr-04 3:30

David Crow

12-Apr-04 3:30

Use PostMessage() to communicate between them.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

copy constructor

packetlos12-Apr-04 3:12

packetlos

12-Apr-04 3:12

Hi there,

If I add a CArray such as CByteArray to a struct like so:

<br />
typedef struct DATAGRAM<br />
{<br />
   // other types here...<br />
   CByteArray pkt_data; 	// Packet data<br />
} DATAGRAM;<br />

and then try and assign something of type DATAGRAM to type DATAGRAM i get the following compile error:
C2558: struct 'DATAGRAM' : no copy constructor available or copy constructor is declared 'explicit'

I know this is because because CByteArray is of dynamic type so I need to provide a copy constructor. So my question is do I need to provide one for DATAGRAM or do I really need to provide one for CByteArray and if so could somebody post a code snippet to help me out?

Cheers

Packetlos

Re: copy constructor

toxcct12-Apr-04 3:50

toxcct

12-Apr-04 3:50

isn't it because you use a struct instead of a class ?

i know C++ enlarge structures capabilities, but i wonder if that's possible...

TOXCCT >>> GEII power

Re: copy constructor

antlers12-Apr-04 5:01

antlers

12-Apr-04 5:01

You don't need to provide one for CByteArray if you provide one for DATAGRAM (that does not rely on CByteArray having a copy constructor)

Re: copy constructor

packetlos12-Apr-04 5:17

packetlos

12-Apr-04 5:17

Thanks toxcct and antlers,

toxcct was right that there in as far as I can see a way to provide a constructor for the struct, therefore I converted it to a class and used CByteArray's .Copy() to provide the assignment.

Smile | :)

Re: copy constructor

Tim Smith12-Apr-04 6:23

Tim Smith

12-Apr-04 6:23

There is little difference between a class and a structure. The only difference is that the default protection is private for a class and public for a structure.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: copy constructor

toxcct12-Apr-04 9:07

toxcct

12-Apr-04 9:07

that's what i was thinking, but in another side, i did never see struct with member functions...
so, here was my doubt.

TOXCCT >>> GEII power

Re: copy constructor

John R. Shaw12-Apr-04 11:05

John R. Shaw

12-Apr-04 11:05

Remember that a struct in C++ is a class that defaults to public access and a normal class defaults to private access. Since DATAGRAM has a dynamic member it does require a copy constructor:

struct DATAGRAM
{
    // other types here...
    CByteArray pkt_data;

    // ctor
    DATAGRAM(DATAGRAM& dg)
    {
        // copy other type here...
        pkt_data.Copy(dg.pkt_data); // Copy packet data
    }
};

Note: I did not use a typedef because it is not needed in C++.

Good Luck! Smile | :)

Now if the blasted Mad | :mad:

power does not go out again, you'll get this message!

INTP

Re: copy constructor

Paul Ranson13-Apr-04 2:03

Paul Ranson

13-Apr-04 2:03

I recommend you use a more modern design of container, perhaps std::vector<unsigned char>. These containers provide a copy constructor so that the compiler default copy constructor for your class will work.

I don't think you should be having to work out how to copy a CByteArray efficiently, or even correctly.

Paul

How can stor a listbox strings with serialization?

Mehdi_Hosseinpour12-Apr-04 2:59

Mehdi_Hosseinpour

12-Apr-04 2:59

I want to store listbox strings in to a file with serialization and load strings from this file with serialization.

Mehdi Hosseinpour

Re: How can stor a listbox strings with serialization?

David Crow12-Apr-04 3:39

David Crow

12-Apr-04 3:39

Something like:

CString str;
CFile file;
file.Open(..., CFile::modeWrite);
CArchive ar(&file, CArchive::store);
for (int x = 0; x < listbox.GetCount(); x++)
{
    listbox.GetText(x, str);
    ar << str;
}
ar.Close();
file.Close();

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: How can stor a listbox strings with serialization?

Ravi Bhavnani12-Apr-04 9:10

Ravi Bhavnani

12-Apr-04 9:10

Might want to ar << listbox.GetCount(); first. Smile | :)

/ravi

My new year's resolution: 2048 x 1536
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ravib@ravib.com

Re: How can stor a listbox strings with serialization?

David Crow12-Apr-04 9:13

David Crow

12-Apr-04 9:13

Of course. I never indicated it was a complete working code example, hence the "Something like" qualifier. When typing this stuff from memory, small details often get omitted.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Re: How can stor a listbox strings with serialization?

Ravi Bhavnani12-Apr-04 9:09

Ravi Bhavnani

12-Apr-04 9:09

See this[^] series of articles.

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

Not able to navigate data between vc++ project and USB device.

Pankaj Bhalla12-Apr-04 2:59

Pankaj Bhalla

12-Apr-04 2:59

Hi All.

The problem I am facing is a bit different. Even I do not know, whether the problem is related to Embedded programming or can be solved with VC++ MFC itself.

I want to send and recieve data between my vc++ application and a USB device. Thats the main issue.

Can anyone tell from where to start or if anyone can help me with the coding that should be done...I will be very thankfull for that help.

Thanks and regards,

Pankaj Bhalla
pankajbhalla@mantraonline.com

Pankaj Bhalla
Consultant - VC++

Re: Not able to navigate data between vc++ project and USB device.

Darshan Jani12-Apr-04 7:21

Darshan Jani

12-Apr-04 7:21

Which USB Device you are talking about.
Please Clarify.

Re: Not able to navigate data between vc++ project and USB device.

Pankaj Bhalla13-Apr-04 0:15

Pankaj Bhalla

13-Apr-04 0:15

Hello Darshan.

Thanks for your consideration and time. Actually, the USB device is itself, under the process of creation. So, not sure about the device, but if you can then please tell me general steps we have to take to make it possible. I mean the articles or any other source from where I can get more information about this issue. If you can the please tell me the MFC classes we can use or any info. about MFC and USB devices.

Thanks and Regards,

Pankaj Bhalla

GDI

Ni@m12-Apr-04 2:42

Ni@m

12-Apr-04 2:42

Where can I download GDI+ librarys and headers?

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