C / C++ / MFC Discussion Boards

ns14-Apr-03 5:15

14-Apr-03 5:15

If I put pragma once in all my .h files that is sufficient to prevent any include multile definition problems right? Is this the same thing as doing #ifndef #define #endif that we see in the MFC .h generated files? If so , pragma once is much easier, so why isnt that used by t he Class wizard instead of the ifndef stuff?

Appreciate your help,
ns

Re: pragma once

User 988514-Apr-03 5:17

User 9885

14-Apr-03 5:17

In VC7, generated headers have only the

#pragma once

line.

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

Re: pragma once

Joaquín M López Muñoz14-Apr-03 5:22

Joaquín M López Muñoz

14-Apr-03 5:22

As you say, both alternatives are equivalent. #pragma once, on the other hand, is not standard C or C++, so in general I prefer the #ifndef guard. As MS guys usually don't bother about standard compliance, I guess they don't use #pragma once only for historical reasons.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Thanks!

ns14-Apr-03 6:13

14-Apr-03 6:13

I shall start using pragma since upto now I didnt do any guard at all....leading to dreaded multiple include issues...

Appreciate your help,
ns

Remote debugging a C++ app

Navin14-Apr-03 5:05

Navin

14-Apr-03 5:05

I have VS.NET, and much to my dismay, I found that it does not install on Windows 98. However, I can install remote debugging components. I expect, then, that if a process is running on that machine, and I have the remote debugging components installed, I can connect to it from my Windows XP machine running VS.NET and do some debugging.

But all I get is an error saying that the remote computer cannot be found. I can get to it other ways (ping, Network Neighborhood, etc.) To add insult to injury, I can even browse for it, pick it, and it *still* says it can't be found!

What's going on? How can I debug on 98? All I am doing is straight C++ here, on fancy .NET framework or managed code.

"When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute and it's longer than any hour. That's relativity." - Albert Einstein

dynamic_cast and static_cast

User 988514-Apr-03 5:05

User 9885

14-Apr-03 5:05

I have a program that uses statis_cast to cast from a base class to a derived class, and is compiled without RTTI.

My question:

What is the risk?
Is there any impact on performance?
Should I release a new version with RTTI and dynamic_cast to prevent any potential problems?

Thomas

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

Re: dynamic_cast and static_cast

Joaquín M López Muñoz14-Apr-03 5:26

Joaquín M López Muñoz

14-Apr-03 5:26

What is the risk?

None, static_cast does not rely on RTTI.

Is there any impact on performance?

Sure, dynamic_cast is more costly.

Should I release a new version with RTTI and dynamic_cast to prevent any potential problems?

Depends on your code. If there's a chance that dynamic_cast can fail (i.e. return 0) and you were using static_cast, then your app is buggy. If not, no need to switch to dynamic_cast anyway Smile | :)

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: dynamic_cast and static_cast

User 988514-Apr-03 5:31

User 9885

14-Apr-03 5:31

Thank you.

Answers all the questions Rose | [Rose]

My article on a reference-counted smart pointer that supports polymorphic objects and raw pointers

modified 29-Aug-18 21:01pm.

MSAccess BatchUpdate throw ADO ?

rosen14-Apr-03 3:58

rosen

14-Apr-03 3:58

Hello.
Does MS Access support BatchUpdates?
I have a project in which im using following code but it gives me an error when there is
more than 2 records in the recordset which have been changed

IDispatch error # 3156 :Number of rows with pending changes exceeds the limit.

<br />
//////////<br />
		_variant_t	v(m_pProject->m_ptrConnection.GetInterfacePtr());<br />
		<br />
		//	Open recordset<br />
		m_pRstBugs->CursorType = adOpenKeyset;<br />
      		m_pRstBugs->LockType = adLockBatchOptimistic;<br />
		m_pRstBugs->Open((LPCTSTR)ProjectName, v,<br />
			adOpenKeyset,adLockBatchOptimistic,adCmdTableDirect);<br />
		<br />
		if (m_pRstBugs->Supports(adIndex) && m_pRstBugs->Supports(adSeek))<br />
		{<br />
			// im making an index<br />
			m_pRstBugs->Index = DBtags::m_sProjectIndexName;<br />
		}<br />
		// ...<br />
		<br />
		<br />
		// here is the problem: Error -> "Number of rows with pending changes exceeds the limit."<br />
		m_pRstBugs->MoveFirst();<br />
		while(!m_pRstBugs->adoEOF)<br />
		{<br />
			_variant_t	x("test");<br />
			m_pRstBugs->Fields->Item["description"]->Value = x;<br />
			m_pRstBugs->MoveNext();<br />
		}<br />
		m_pRstBugs->UpdateBatch(adAffectAll);<br />
		//	end test<br />
		<br />

Re: MSAccess BatchUpdate throw ADO ?

Dave Kreskowiak14-Apr-03 5:05

Dave Kreskowiak

14-Apr-03 5:05

I'm not sure how many changes are supported, but I think(!) the Jet Database Engine only supports 1. You might want to check out the "Maximum Pending Rows" property of your RecordSet object before making any changes.

The article for the property is on MSDN at
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/adosql/adoprg04_9cop.asp

RageInTheMachine9532

Enumerate and Disconnect LAN

Ceri14-Apr-03 3:21

Ceri

14-Apr-03 3:21

Does anybody know how I would enumerate LAN connections and disconnect them. I know you can do this with the RAS API for dial-up connections but I am not sure if it works with LAN connection

Thanks
Ceri

CStdioFile and Seek-Method

tabor2514-Apr-03 3:09

tabor25

14-Apr-03 3:09

Hello,

i am using a CStdioFile object to read in a text-file. On some positions within the file i have to seek. I do it like this:

CString line;
CStdioFile file;
...

/* Read a few lines */
while (condition) {
file.ReadString(line)
/* do something with line */
}

/* Save current start-position for new line */
DWORD pos = file.GetPosition();

/* Read a few lines */
while (condition) {
file.ReadString(line)
/* do something with line */
}

/* Go back to saved position */
file.Seek(pos,CFile::begin);

Positioning the file-pointer by using the seek-method works only correct, if every line has a 0A 0D at the end. Now i have to parse a file that only has 0A at the end and the seek-method fails. It sets the file-pointer to the middle of a line and not to the beginning of the expected line. Please help!

Best regards

tabor25

Re: CStdioFile and Seek-Method

valikac14-Apr-03 7:46

valikac

14-Apr-03 7:46

Do you know whether ReadString() appends or overwrite previous data in a CString object?

Kuphryn

Re: CStdioFile and Seek-Method

tabor2514-Apr-03 20:06

tabor25

14-Apr-03 20:06

Hello Kuphryn,

ReadString() overwrites the previous data in the Cstring object.

Best regards

tabor25

How do you move a window without showing it?

Abin14-Apr-03 3:04

Abin

14-Apr-03 3:04

Hi, I have a whindow which is currently minimized, now for some particular reason I must set it to be a foreground window for a short moment, but I do not want the user to see it. So the best way to do so, I guess, is to restore the window then immediately move it off screen(e.g., call "::MoveWindow" and give it a CRect(-999, -999, 100, 100), or something like that).

Now the problem is that, since calling "::MoveWindow" while the window is minimized has NOT effect, I must first restore the window by calling "ShowWindow(hwnd, SW_RESTORE)", at that time, before it gets moved off screen, the window displays on screen for one second or two, and that will annoy my user.

So, is there anyway I can move a previously minimized window off screen without letting it show on the visible screen area at all? Thanks.

Re: How do you move a window without showing it?

Rage14-Apr-03 6:01

Rage

14-Apr-03 6:01

And the following :

Hide -> Restore -> Move -> Show ? Cn you hide it while it is minimized ?

~RaGE();

won't work

Abin14-Apr-03 13:36

Abin

14-Apr-03 13:36

Since SW_RESTORE will display the window regardless of its previous state.

Visual studio Add-In

Rage14-Apr-03 2:48

Rage

14-Apr-03 2:48

Hi !

I have programmed a visual c++ add-in, which runs fine on all our visual c++'s but one, which throws the error : add-in cannot be registered because DllRegisterServer() fails. Add-in will not be loaded again. (Merely translated from German Blush | :O

).

There is no memory error, registry can be accessed, so any idea of what could be the problem ?

Platform is WinNT 4.0 SP 5.0, Visual C++ 6.0.

~RaGE();

Re: Visual studio Add-In

Zdeslav Vojkovic14-Apr-03 4:03

Zdeslav Vojkovic

14-Apr-03 4:03

use depends.exe to check if some of the dlls needed by add-in are missing

Looking for graphing components

Anonymous14-Apr-03 2:39

Anonymous

14-Apr-03 2:39

Can anyone recommend a good package of charting components? I've downloaded a demo of GigaSoft ProEssentials and that's the sort of thing I'm looking for. I don't know what else is out there and I'd like to know how it compares with other packages. I'm more interested in scientific applications, including plotting in real time as data is collected, than simple pie charts, etc. Thanks for your help.

How to make a multiline cell in MFCGridctrl

Bilal Akram14-Apr-03 2:35

Bilal Akram

14-Apr-03 2:35

hi every bdy,
does ny bdy here know how to make a cell, in MFCGridCtrl multiline. Like if the text is more than the width of the cell than it should go into the next line. I have tried using SetItemFormat nRow,0,ES_MULTILINE|ES_AUTOVSCROLL|ES_WANTRETURN) with these parameters but i doesnt seems to work. I would be really greatful if ny bdy could help me in this regard

regards,
Bilal.
Email bilal793@yahoo.com

Re: How to make a multiline cell in MFCGridctrl

cr9714-Apr-03 3:54

cr97

14-Apr-03 3:54

It works ...

but you have to change the autosize-function ... the actual autosize calculates a height for only one line of text !!!

Look at http://www.codeproject.com/miscctrl/gridctrl.asp ...

Search for multi-line, word-wrap etc.

cr97

Re: How to make a multiline cell in MFCGridctrl

Bilal Akram14-Apr-03 4:25

Bilal Akram

14-Apr-03 4:25

thanks for replying ...
i hve even changed the height of the rows ... but its still not working ... i hve read the whole document of gridctrl.asp again nd looked for the words u mentioned, but they are not there ...
is it somehow possible for u to make a small application in which there is a cell with multiline ... i would reallly appreciate it

regards
Bilal

Re: How to make a multiline cell in MFCGridctrl

cr9714-Apr-03 22:06

cr97

14-Apr-03 22:06

oh sorry ... i mean the message board there ...

try this ...

Re: How to make a multiline cell in MFCGridctrl

Bilal Akram15-Apr-03 22:51

Bilal Akram

15-Apr-03 22:51

thanks chris ... i hve managed to solve the problem Smile | :)

thanks for replying and ur help .. Smile | :)

regards
Bilal.

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