database schema design question - C / C++ / MFC Discussion Boards

Re: How to change CDocument Variables from within the CWinApp derived Class?

Franken15-Nov-05 23:47

Franken

15-Nov-05 23:47

Now it works Smile | :)

somehow. The runtime error only occur if I try to place this code in the worker thread, not if it is placed somewhere else in the main application class. But I think I can find a solution for that.

Thanks.

Re: How to change CDocument Variables from within the CWinApp derived Class?

David Crow16-Nov-05 3:10

David Crow

16-Nov-05 3:10

Franken wrote:
Now it works somehow.

This is usually a good indication that the problem still exists and has simply been masked or moved to a new location.

Franken wrote:
The runtime error only occur if I try to place this code in the worker thread,

Which makes sense as worker threads shouldn't be accessing such information. See these two articles for more on threads and how they are supposed to communicate back and forth with the primary thread.

http://www.flounder.com/workerthreads.htm

http://www.flounder.com/uithreads.htm

"Take only what you need and leave the land as you found it." - Native American Proverb

error LNK2001: unresolved external symbol

celllllllll15-Nov-05 6:53

celllllllll

15-Nov-05 6:53

Hi All,

Can you guys please help me resolving this error?

Thanks in advance

Preeti9

Re: error LNK2001: unresolved external symbol

David Crow15-Nov-05 7:20

David Crow

15-Nov-05 7:20

You've not provided enough information. See here for possibilities.

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: error LNK2001: unresolved external symbol

celllllllll15-Nov-05 7:31

celllllllll

15-Nov-05 7:31

Sorry for not providing enough info...

Here are the errors listed:
[code]
Linking...
MSVCRT.lib(MSVCRT.dll) : error LNK2005: __vsnprintf already defined in LIBCMT.lib(vsnprint.obj)
MSVCRT.lib(MSVCRT.dll) : warning LNK4006: __vsnprintf already defined in LIBCMT.lib(vsnprint.obj); second definition ignored
Creating library ReleaseMinSize/WosaIDC.lib and object ReleaseMinSize/WosaIDC.exp
LINK : warning LNK4098: defaultlib "MSVCRT" conflicts with use of other libs; use /NODEFAULTLIB:library
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSClose@4
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSDeregister@12
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFMSetTimer@16
CardReaderEvent.obj : error LNK2001: unresolved external symbol _WFMSetTimer@16
CardReaderOper.obj : error LNK2001: unresolved external symbol _WFMSetTimer@16
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSRegister@12
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFMSetTraceLevel@8
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSOpen@36
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFMKillTimer@4
CardReaderEvent.obj : error LNK2001: unresolved external symbol _WFMKillTimer@4
CardReaderOper.obj : error LNK2001: unresolved external symbol _WFMKillTimer@4
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSFreeResult@4
CardReaderEvent.obj : error LNK2001: unresolved external symbol _WFSFreeResult@4
CardReaderOper.obj : error LNK2001: unresolved external symbol _WFSFreeResult@4
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSExecute@20
CardReaderDev.obj : error LNK2001: unresolved external symbol _WFSGetInfo@20
CardReaderOper.obj : error LNK2001: unresolved external symbol _WFSCancelAsyncRequest@8
CardReaderOper.obj : error LNK2001: unresolved external symbol _WFSAsyncExecute@24
CardReaderReg.obj : error LNK2001: unresolved external symbol _WFMCloseKey@4
CardReaderReg.obj : error LNK2001: unresolved external symbol _WFMQueryValue@16
CardReaderReg.obj : error LNK2001: unresolved external symbol _WFMSetValue@16
CardReaderReg.obj : error LNK2001: unresolved external symbol _WFMCreateKey@16
CardReaderReg.obj : error LNK2001: unresolved external symbol _WFMOpenKey@12
LIBCMT.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
ReleaseMinSize/WosaIDC.dll : fatal error LNK1120: 18 unresolved externals
Error executing link.exe.

WosaIDC.dll - 26 error(s), 2 warning(s)
[\code]

I have included all the lib files also..But still I am getting 26 errors.

Thanks again

Preeti9

Re: error LNK2001: unresolved external symbol

tranglt15-Nov-05 18:55

tranglt

15-Nov-05 18:55

Dear u!
do you use Visual C++ 6.0?
you set again Option setting.
Project/Setting/ Link ..
I Hope that is useful to you!
Best regards.

-- modified at 0:56 Wednesday 16th November, 2005

Re: error LNK2001: unresolved external symbol

sunit515-Nov-05 20:18

sunit5

15-Nov-05 20:18

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccore98/html/lnk2001.asp

database schema design question

ppp00115-Nov-05 6:43

ppp001

15-Nov-05 6:43

Hi,

I have two objects, both point to each other in OO.
e.g.
Class Father
{
private int id; //id of father
private Son son;
}
Class Son
{
private int id; //id of Son
private Father father;
}

so I need to have two tables in database as follow,

Table Father :
(id, SonId)

Table Son :
(id, FatherId)

The problem is, should I eliminate the one of the reference in one of the table, e.g.

Table Father :
(id)

Table Son :
(id, FatherId)

so I just have the fatherID in the son table.
But if I remove the sonID from the father table,
I need to join the two tables when I retrieve fathers
from the father table.
So what are the pros and cons of the two schema design ?

Thanks

Re: database schema design question

Mayur Mahajan15-Nov-05 14:36

Mayur Mahajan

15-Nov-05 14:36

If you keep the references in both the tables, you can improve the efficiency by eliminating joins. You can find all 'children' of a 'father' and vice versa by a simple query on a single table.
The down side however is an additional overhead in maintaining the redundant data consistently. You need to make sure to update the respective fields whenever any child is to be deleted or the other way. Just see what is preferable for your application, efficiency or simplicity...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

do not show MFC Window

inf00915-Nov-05 6:30

inf009

15-Nov-05 6:30

I am trying that my program does some task before calling MFC class:

#include <afxwin.h>

class MFC_Window :public CFrameWnd
{
public:
MFC_Window()
{
Create(NULL,_T("whatever"));
}
};

class MyApp :public CWinApp
{
MFC_Window *wnd;
public:
BOOL InitInstance()
{
wnd = new MFC_Window();
m_pMainWnd = wnd;
m_pMainWnd->ShowWindow(1);
return 1;
}
};

int main ()
{
// some tasks...

if (some tasks == true) MyApp theApp;
}

Calling MFC from main() does not work. Does anybody know how to do this? Or how to put the MFC as not visible?

Thanks,
Christian

Re: do not show MFC Window

David Crow15-Nov-05 7:18

David Crow

15-Nov-05 7:18

Just for clarity, MFC is not a class nor is it callable.

What exactly is it that you are wanting to do prior to displaying any sort of window?

Deriving from CFrameWnd indicates that you are working on an application. Thus you'll not be able to use main().

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: do not show MFC Window

__yb15-Nov-05 10:56

__yb

15-Nov-05 10:56

If I understand u correctly u want to do things before showing the main window.
To do this u don't have to mangle with main(), WinMain() nor constructing MyApp yourself. All u have to do is put some code in MyApp::InitInstance() before the window creation/show.

Just to comment few other things:
First, the way u try to initialize MyApp is invalid syntax.
If u follow the MFC App Wizard, MyApp is created on the "global stack" - the standard library initializes it before calling main().
Second, u can track down MFC's WinMain (just look at the call stack) and alter it. But your code will not run there unless u compile MFC itself.

HTH

Re: do not show MFC Window

inf00916-Nov-05 6:13

inf009

16-Nov-05 6:13

Thank you for your replies.

Yes, what I am trying to do is to do things before showing the main window, or not to show it at all. My programm enumerates NFC boards, and if it detects more than 1, a window should pop up and ask user to select one of them. If it only finds one board, the app should select that board and the window shouldnt pop up.

I tried to set the visible property to false, but nothing happened!?!? The only thing I can imagine is that the release build wont show the window, I dont know and didnt try it.

Thanks

DrawText !!

hatemtaleb15-Nov-05 6:24

hatemtaleb

15-Nov-05 6:24

Hi everybody,
I'am using the DrawText function to draw this text "p&m":
DrawText(_T("p&m"),LPRECT(CRect(0,0,100,100)),DT_LEFT);
but my problem is that the text on the screen appear with the 'm' underlined.

could someone help me!!

thanks.

Re: DrawText !!

Mike Dimmick15-Nov-05 6:30

Mike Dimmick

15-Nov-05 6:30

Either double the & character, or use the DT_NOPREFIX flag (i.e. specify DT_LEFT | DT_NOPREFIX).

This feature is intended for use by various Windows functions to indicate accelerator keys for activating controls. Windows 2000 and higher, by default, hide the accelerator key indicators until the Alt key is pressed, so you may not have seen this behaviour.

Stability. What an interesting concept. -- Chris Maunder

Re: DrawText !!

mikanu15-Nov-05 6:31

mikanu

15-Nov-05 6:31

What you are experiencing is windows' method of representing shortcuts. So what you have to do in order to get the text "p&m" is to use the folowing ampersand escape sequence:

DrawText(_T("p&&m"), LPRECT(CRect(0,0,100,100)), DT_LEFT);

For more details look up escape characters on msdn

Re: DrawText !!

hatemtaleb15-Nov-05 7:09

hatemtaleb

15-Nov-05 7:09

DrawText(_T("Thank you Mike && mikanu for your help"), LPRECT(CRect(0,0,100,100)), DT_LEFT | DT_NOPREFIX) Wink | ;)

VS6: Enabling breakpoints per thread

Chintoo72315-Nov-05 6:04

Chintoo723

15-Nov-05 6:04

In Visual Studio 6, is it possible to enable breakpoints only for a certain thread? It is little annoying when the debugging context suddenly changes to another thread.

If it is not possible in Visual Studio 6, is it possible atleast in WinDbg?

thanks!

Re: VS6: Enabling breakpoints per thread

David Crow15-Nov-05 7:22

David Crow

15-Nov-05 7:22

You can put conditions on breakpoints. If you have a variable that represents the active thread, you could use that.

"Take only what you need and leave the land as you found it." - Native American Proverb

LNK2001 error

yongwpi15-Nov-05 4:50

yongwpi

15-Nov-05 4:50

I attempted to use WMF SDK, but ran into link error.

DRMShow.cpp
Generating Code...
Linking...
WMStubDRM_38503.lib(so3.obj) : error LNK2001: unresolved external symbol __ftol2
WMStubDRM_38503.lib(rc4safe.obj) : error LNK2001: unresolved external symbol __SEH_epilog
WMStubDRM_38503.lib(cpu.obj) : error LNK2001: unresolved external symbol __SEH_epilog
WMStubDRM_38503.lib(rc4safe.obj) : error LNK2001: unresolved external symbol __SEH_prolog
WMStubDRM_38503.lib(cpu.obj) : error LNK2001: unresolved external symbol __SEH_prolog
Debug/DRMShow.exe : fatal error LNK1120: 3 unresolved externals
Error executing link.exe.

Yong

Re: LNK2001 error

David Crow15-Nov-05 4:55

David Crow

15-Nov-05 4:55

yongwpi wrote:
WMStubDRM_38503.lib(rc4safe.obj) : error LNK2001: unresolved external symbol __SEH_epilog
WMStubDRM_38503.lib(cpu.obj) : error LNK2001: unresolved external symbol __SEH_epilog
WMStubDRM_38503.lib(rc4safe.obj) : error LNK2001: unresolved external symbol __SEH_prolog
WMStubDRM_38503.lib(cpu.obj) : error LNK2001: unresolved external symbol __SEH_prolog

Doesn't this require linking with sehprolg.obj?

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: LNK2001 error

Michael Dunn15-Nov-05 8:25

Michael Dunn

15-Nov-05 8:25

Are you using VC6? If so, you're SOL. MS stopped releasing VC6-compatible LIBs a couple years ago.

--Mike--
Visual C++ MVP Cool | :cool:

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how to retrieve a HANDLE from a pointer?

ewighell15-Nov-05 4:49

ewighell

15-Nov-05 4:49

many functions require parameters of type HANDLE. how to get it? take the following for instance:

CEdit *pEdit;
pEdit = new CEdit();
pEdit->Create(0,rect,this,IDC_EDIT1);
// how can I get a handle to the Edit window?
...
delete pEdit;

Thank you very much!!!

-------------------
I am learning C++ and English

Re: how to retrieve a HANDLE from a pointer?

David Crow15-Nov-05 4:57

David Crow

15-Nov-05 4:57

ewighell wrote:
// how can I get a handle to the Edit window?

Use the GetSafeHwnd() method. However, why do you need it?

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: how to retrieve a HANDLE from a pointer?

ewighell15-Nov-05 15:44

ewighell

15-Nov-05 15:44

I want to send a message with the function SendMessage(), it seems that some of its parameters are of type HWND.
I want to send a BN_CLICKED message to the button m_bn1, which is of type CButton with the following code, but it seems does not work, where am I wrong?

SendMessage(BN_CLICKED,IDC_BUTTON1,(LPARAM)m_bn1.GetSafeHwnd());

Thank you very much!!!

-------------------
I am learning C++ and English

-- modified at 21:47 Tuesday 15th November, 2005

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