C / C++ / MFC Discussion Boards

Jörgen Sigvardsson23-Mar-03 5:24

23-Mar-03 5:24

You should probably post this in the lounge[^]. You'll get a lot more answers then (relevant as well as irrelevant Wink | ;)

).

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Any solution to class redefinition

boon kian22-Mar-03 23:06

boon kian

22-Mar-03 23:06

Hi

Anyone have a solution for class redefinition ??

I have a based class and 2 derived class. When i try to write a main function using both the derived class i have a class redefinition problem. Can anyone guide me on how to solve the prob ??

Thanx a lot !!!

bk

Re: Any solution to class redefinition

Anonymous23-Mar-03 0:20

Anonymous

23-Mar-03 0:20

Its not very clear what you mean, maybe you can give an example of what you are trying to do?

Re: Any solution to class redefinition

boon kian23-Mar-03 0:46

boon kian

23-Mar-03 0:46

eg:

base class :
class Employee
{

}

derived class 1:

class Temp:public Employee
{

}

derived class 2:

class Perm:public Employee
{

}

main:

#include "Perm.h"
#include "Temp.h" <- this is where the redefinition occur due to 2 copy of "Employee.h"

void main (void)
{
Temp a;
Perm b;
......
}

so beside changing the structure any solution to solve this prob ??

thanx a lot !!

bk

Re: Any solution to class redefinition

Jörgen Sigvardsson23-Mar-03 1:47

Jörgen Sigvardsson

23-Mar-03 1:47

You need to protect the header file from multiple inclusions.

A portable way is to do something like this:

#ifndef __FILE_H__
#define __FILE_H__

// Header file contents here

#endif // __FILE_H__

If you are not worried about portability and is using VS.NET, you can write something like this:

#pragma once
// Header file contents here

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Re: Any solution to class redefinition

Stephane Rodriguez.23-Mar-03 3:06

Stephane Rodriguez.

23-Mar-03 3:06

#pragma once

huh?

Re: Any solution to class redefinition

Jörgen Sigvardsson23-Mar-03 3:24

Jörgen Sigvardsson

23-Mar-03 3:24

It automatically protects header files. A VS.NET extension which IMHO should be incorporated into C/C++. Idiot proof protection! Big Grin | :-D

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Shine, awaken me - shine
Shine for all your suffering - shine

Re: Any solution to class redefinition

Stephane Rodriguez.23-Mar-03 4:29

Stephane Rodriguez.

23-Mar-03 4:29

me leaving the class room looking down my shoes. Wink | ;)

[edit]#pragma once is not a VS.NET extension.[/edit]

Re: Any solution to class redefinition

Jörgen Sigvardsson23-Mar-03 5:21

Jörgen Sigvardsson

23-Mar-03 5:21

.S.Rod. wrote:
[edit]#pragma once is not a VS.NET extension.[/edit]

Did it appear earlier? I assumed it was first included in VS.NET because VS.NET was the first environment where I noticed that the wizards generate code containing #pragma once.

Speaking of extensions, do you know by any chance if you can force folding points in C++ source files using some [un]documented trick? #region is what I want, but that seems to be a C# only feature.

--
Shine, enlighten me - shine
Shine, awaken me - shine
Shine for all your suffering - shine

Re: Any solution to class redefinition

Stephane Rodriguez.23-Mar-03 5:41

Stephane Rodriguez.

23-Mar-03 5:41

Jörgen Sigvardsson wrote:
Did it appear earlier? I assumed it was first included in VS.NET because VS.NET was the first environment where I noticed that the wizards generate code containing #pragma once.

As far as I can tell it was already available with MSDEV 97.

Jörgen Sigvardsson wrote:
Speaking of extensions, do you know by any chance if you can force folding points in C++ source files using some [un]documented trick? #region is what I want, but that seems to be a C# only feature.

There is no way to force outlining. But the context menu shows a way to play with outlines regardless of the language you are using (they are saved in the .suo file, like bookmarks and other stuff). More info here[^].

Re: Any solution to class redefinition

Jörgen Sigvardsson23-Mar-03 6:37

Jörgen Sigvardsson

23-Mar-03 6:37

.S.Rod. wrote:
But the context menu shows a way to play with outlines regardless of the language you are using (they are saved in the .suo file, like bookmarks and other stuff).

Yeah, I knew about that one. However, the .suo file is nothing I want to keep in CVS. The main reason I wanted to add the regions was to promote readability (hiding all the private stuff as much as possible which is of no interest anyway for the user of the class) and have it inlined in the code. Oh well, I guess I can't have everything. Smile | :)

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Shine, awaken me - shine
Shine for all your suffering - shine

Re: Any solution to class redefinition

R^eservoir D^og23-Mar-03 23:57

R^eservoir D^og

23-Mar-03 23:57

It's not really a VS.NET extension coz i've used #pragma once in VC++ 6 also. Though not sure if it was present in earlier versions too or not.

And you will know my name is the Lord when I lay my vengeance upon thee.

Re: Any solution to class redefinition

boon kian23-Mar-03 17:40

boon kian

23-Mar-03 17:40

Hi ,

Really thanx a lot for the help !!!

bk

Re: Any solution to class redefinition

Jörgen Sigvardsson23-Mar-03 1:48

Jörgen Sigvardsson

23-Mar-03 1:48

Oh yeah, i forgot to mention that the define at the top of each header file should be unique for each header file.

I usually use this pattern:
If the file is called file.h, the define symbol becomes __FILE_H__

So, if I had Employee.h, I'd define the symbol as __EMPLOYEE_H__

Smile | :)

--
Shine, enlighten me - shine
Shine, awaken me - shine
Shine for all your suffering - shine

Would a kind soul...

Rob Manderson22-Mar-03 19:26

Rob Manderson

22-Mar-03 19:26

check their copy of windows.h and let me know if it has these lines maybe 20 lines from the start?

C++

#if(WINVER >= 0x0500)
#pragma message ("")
#pragma message ("NOTE: WINVER has been defined as 0x0500 or greater which enables")
#pragma message ("Windows NT 5.0 and Windows 98 features. When these headers were released,")
#pragma message ("Windows NT 5.0 beta 1 and Windows 98 beta 2.1 were the current versions.")
#pragma message ("")
#pragma message ("For this release when WINVER is defined as 0x0500 or greater, you can only")
#pragma message ("build beta or test applications.  To build a retail application,")
#pragma message ("set WINVER to 0x0400 or visit http://www.microsoft.com/msdn/sdk")
#pragma message ("to see if retail Windows NT 5.0 or Windows 98 headers are available.")
#pragma message ("")
#pragma message ("See the SDK release notes for more information.")
#pragma message ("")
#endif

I found them lurking in my copy of windows.h but when I went to the PSDK site at Microsoft to update it tells me I already have the latest version installed.

Rob Manderson

http://www.mindprobes.net

Re: Would a kind soul...

Michael Dunn22-Mar-03 20:25

Michael Dunn

22-Mar-03 20:25

That shows you how OLD VC 6 is. Wink | ;)

"Windows NT 5.0" is what we now call Win 2000. You should be using the PlatSDK include & lib dirs instead of the ones that shipped with VC, so you'll never see that message. Assuming you have a recent PSDK, you can click on Visual Studio Registation->Register PSDK Directories with Visual Studio in the PSDK program group to put the dirs in VC's search path.

--Mike--
THERE IS NO THERE IS NO BUT THERE IS MAGIC PIXIE DUST BUSINESS GENIE CODE PROJECT

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Re: Would a kind soul...

Rob Manderson22-Mar-03 20:47

Rob Manderson

22-Mar-03 20:47

Aha!!!! Now I know why some constants weren't defined! I've installed the platform SDK within the last three months (when I arrived in the US and put my new machine together) but I never thought to update the search paths in Visual Studio... Doh!!! Wink | ;)

Thanks Mike Wink | ;)

Rob Manderson

http://www.mindprobes.net

How to disable key 'Print Screen' or others in MFC ?

CS42922-Mar-03 19:11

CS429

22-Mar-03 19:11

hello I need help ,I want to disable key 'print screen' and 'Ctrl+C' and 'Ctrl+V' in MFC(use CRichEditCtrl) but I don't know how to do,Please help
thank you.
i am a student in thailand

I need a equation thingy

Anonymous22-Mar-03 17:09

Anonymous

22-Mar-03 17:09

I need a class of some sort that takes an equation like 12391+19-334+x^2=d^4*123 or somthing and it must find when the values of x and d or more values multiple values are correct but it must accept a string type? As in the equation will be located within a string. DDoes anyone know where I can find a program that does this? Exactly?

Re: I need a equation thingy

Jörgen Sigvardsson24-Mar-03 0:46

Jörgen Sigvardsson

24-Mar-03 0:46

Mathcad? Maple?

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Shine, enlighten me - shine
Shine, awaken me - shine
Shine for all your suffering - shine

KillTimer() inside a TimerProc?

Moak22-Mar-03 16:27

Moak

22-Mar-03 16:27

Hi,
is it safe to call KillTimer() inside a TimerProc? MSDN does not mention it's bad for a timer proc to stop it's timer, just want to make sure I'm not doing something evil...

Thanks, Moak

Re: KillTimer() inside a TimerProc?

567890123423-Mar-03 1:42

5678901234

23-Mar-03 1:42

Yes, it's OK.

Re: KillTimer() inside a TimerProc? - thx

Moak23-Mar-03 13:20

Moak

23-Mar-03 13:20

thanks

SHFileOperation: making new folders?

IGx8922-Mar-03 15:34

IGx89

22-Mar-03 15:34

Is it possible to have SHFileOperation automatically create new folders when copying files? For instance: "d:\testfile.txt" to "d:\somefolderthatdoesn'tcurrentlyexist\testfile.txt". If it doesn't do that, is there an easy way to get around that limitation, without having to do some complex string parsing to find and make new folders?

Re: SHFileOperation: making new folders?

Ravi Bhavnani23-Mar-03 9:52

Ravi Bhavnani

23-Mar-03 9:52

I'll be posting my FileSystem article soon. It provides this and other convenient functions. Meanwhile, here's the logic:

long FileSystem::createDir
  (CString strDirectory)  // directory
{
  // Return if directory already exists
  if (dirExists (strDirectory))
     return (Status::Duplicate);
 
  // First create parent directory - return if unable
  CString strDirParent;
  getParentDir (strDirectory, strDirParent);
  if (!strDirParent.IsEmpty() && !dirExists (strDirParent))
     {
       long nStatus = createDir (strDirParent);
       if (nStatus == FileSystem::Status::Error)
          return (nStatus);
     }
 
  // Then create directory
  DWORD dwStatus = ::CreateDirectory (strDirectory, NULL);
  if (dwStatus == 0)
     return (Status::Error);
  return (Status::Success);
}

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

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