C / C++ / MFC Discussion Boards

John M. Drescher18-Apr-04 18:13

18-Apr-04 18:13

I get back on the rest if I have some time.

dreamerzz wrote:
And I tried using thread function with database. But it has some errors on the recordset that i have used. can u advice me on this issue?

This is because DAO is not multithreaded. There are workarounds for this but it is much better to use ADO to connect to the database. I use ado and connect with any of the threads in my program with no problems at all. A good ado article is here:
http://www.codeproject.com/database/caaadoclass1.asp

John

Re: CWinThread "issues"

dreamerzz20-Apr-04 2:15

dreamerzz

20-Apr-04 2:15

Hi,

Thanks for ur help and advice

dReaMerzZ

Re: CWinThread "issues"

John M. Drescher20-Apr-04 4:28

John M. Drescher

20-Apr-04 4:28

Sorry I did not get the rest of the info for you. I am behind on a very important deadline and I do not have a lot of time.

John

Creating string from BSTR

yanuart12-Apr-04 6:25

yanuart

12-Apr-04 6:25

I know how to make a BSTR from a CString object but can't find the way to do the other way around.
Does anyone know how to create a CString object from a BSTR ??

Re: Creating string from BSTR

Darshan Jani12-Apr-04 7:02

Darshan Jani

12-Apr-04 7:02

Suppose you have :
BSTR b; // Allocate this by SysAllocString API
CString s;
then use:
s=b;

So simple.:-DOK It will work.

Regards,
Darshan Jani

Re: Creating string from BSTR

GuimaSun12-Apr-04 7:07

GuimaSun

12-Apr-04 7:07

Is this what you want ?

BSTR bstr = SysAllocString( L"abc" );
CString cs;
cs = bstr;

GuimaSun
www.nexsun.com.br

Keep the Client DC state in a Bitmap

stelitsisan12-Apr-04 5:40

stelitsisan

12-Apr-04 5:40

Hello,
At the moment I am outputing a bitmap on the screen and when it resizes etc. it redraws that bitmap ok. I need to output more bitmaps to the screen and when it need to be redrawn to display all of them. How can I do that? I tried double-buffering but I don't know how to add the "small" bitmaps to the off-screen bitmap.
Thanks

Customized CFileDialog

benny232312-Apr-04 5:28

benny2323

12-Apr-04 5:28

Hi,

I am trying to customize the CFileDialog. I want to have the select multiple files feature to turn on and off based on the user behavior (e.g. click a button on this customized dialog). Is it possible to do that ? I only know that it works only if I set the ofn flag to OFN_ALLOWMULTISELECT before intialize.

Thanks.

Re: Customized CFileDialog

David Crow12-Apr-04 7:40

David Crow

12-Apr-04 7:40

I'm not seeing that it makes any sense to ask the user if they want to select multiple files or not. Depending on the context in which files are selected, that feature should be determined by the program. What are the conditions that would toggle it one way or the other?

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

Re: Customized CFileDialog

benny232312-Apr-04 8:36

benny2323

12-Apr-04 8:36

Actually the customize dialog will have 2 different sets of display. One of them only allows the user to select a single file, while the other one is intended to allow them to select multiple files. In both case the program will do some customize validation before opening the file(s). There will be a button for them to switch between the displays.

The reason i do this is because select multiple files won't allow work in different directories. I actually put a list box in this customize dialog to store the selected files such that when user browse to different directories, the previous selected files will not be lost.

Re: Customized CFileDialog

David Crow12-Apr-04 9:22

David Crow

12-Apr-04 9:22

benny2323 wrote:
The reason i do this is because select multiple files won't allow work in different directories.

I assume you know what folders are multiple-select and what folders are single-select before displaying the dialog. While you probably aren't allowing the button to switch to multiple-select mode when in a single-select folder, it doesn't make much sense to be in a multiple-select folder and have the button switch to single-select mode.

Realize that I'm making this observation based on the very little information that's been provided, but it just seems to stray too far from the (de facto) standard.

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

My Service gets stopped when checked for dependensies

Anonymous12-Apr-04 5:01

Anonymous

12-Apr-04 5:01

My Service gets stopped when checked for dependensies through SCM.
ie, scm->rgt click->Properties->Dependencies

Then my CallBack function (for service stopping)gets called.

_variant_t causing linker error

yanuart12-Apr-04 4:23

yanuart

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.

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