C / C++ / MFC Discussion Boards

technique for assure, that a function is overwritten in c++??

schaereran@gmx.net4-Mar-04 21:36

4-Mar-04 21:36

hy, i have a virtual function in a class. i must go sure, that every class who is inherited from this class overwrites this function, otherwise a warning shoud occur at runtime, or something like that. is this possible??

thanx andreas

Re: technique for assure, that a function is overwritten in c++??

Prakash Nadar4-Mar-04 22:00

Prakash Nadar

4-Mar-04 22:00

in the base class make the functino pure virtual
like

virtual void somefunction() = 0; //pure virtual function.

this ensures that the derived class has to override/implement the method.

Re: technique for assure, that a function is overwritten in c++??

schaereran@gmx.net4-Mar-04 23:09

schaereran@gmx.net

4-Mar-04 23:09

yes, but i need a technique, who workes also when i derive a class from a derived class and so on!
is there any trick?

Re: technique for assure, that a function is overwritten in c++??

Prakash Nadar4-Mar-04 23:36

Prakash Nadar

4-Mar-04 23:36

Please do read about pure virtual function.

Re: technique for assure, that a function is overwritten in c++??

schaereran@gmx.net4-Mar-04 23:48

schaereran@gmx.net

4-Mar-04 23:48

yes, but what, if i make a pure virtual function (abstract class) then derive a class from it, and implement this function. now i derive a class from this class, and forget to overwritte this function, how will i know?

Re: technique for assure, that a function is overwritten in c++??

Robert A. T. Káldy5-Mar-04 0:11

Robert A. T. Káldy

5-Mar-04 0:11

It will cause a compile error.

Robert-Antonio

"CRAY is the only computer, which runs an endless loop in just 4 hours"

Re: technique for assure, that a function is overwritten in c++??

Prakash Nadar5-Mar-04 0:41

Prakash Nadar

5-Mar-04 0:41

It doesnt for the second derivation.

Re: technique for assure, that a function is overwritten in c++??

schaereran@gmx.net5-Mar-04 1:36

schaereran@gmx.net

5-Mar-04 1:36

there is no complie error(on the 2th. deriv)!!!

is there any trick, or technique, that could give me
a compile error?

Re: technique for assure, that a function is overwritten in c++??

Prakash Nadar5-Mar-04 0:43

Prakash Nadar

5-Mar-04 0:43

If you derive the class from CObject in MFC then i guess you can use the RTTI to determine which object's method is called and then generate the error accordingly.

Re: technique for assure, that a function is overwritten in c++??

schaereran@gmx.net5-Mar-04 2:16

schaereran@gmx.net

5-Mar-04 2:16

so it would be possible that, whenever someone is calling the function, who is not overwritten (and therefore the one of the superclass is called) it throws an error?

that would be grat!

Re: technique for assure, that a function is overwritten in c++??

S van Leent5-Mar-04 10:17

S van Leent

5-Mar-04 10:17

Maybe some light.

Any function has its start address. So you can check whether the start address of the function in the derived class is the same as the address of the function in the super class itself. If so, you could fault on runtime.

It has some difficulties, and some knowledge of vtables seem to be handy here, but I think it is in the direction you should be thinking.

LPCTSTR Dutch = TEXT("Double Dutch Smile | :)

");

Re: technique for assure, that a function is overwritten in c++??

Joe Woodbury6-Mar-04 11:57

Joe Woodbury

6-Mar-04 11:57

No.

This is a very serious design flaw in C++.

(It gets worse. Say you created a function of the same name in the inherited class, but very slightly changed one of the parameters. You're screwed.)

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

Detect Debug Exes

tojamismis4-Mar-04 21:34

tojamismis

4-Mar-04 21:34

Hey... Got a question about detecting debug vs. release configurations. I am working with an app at work that gave me an assertion error the other day. It included the filename and the line number in the error message. This would mean that the EXE we got from the vendor was compiled with DEBUG flags on. (I'm sort of a newbie (6 months as a convert from VB6).)

My question is... is there any way to tell whether an exe or dll was compiled with Win32 Debug configuration without opening in a hex editor and looking for extra symbols? (I'm trying to see if I can automate the process for a software test team.)

Thanks!

Tojam

Re: Detect Debug Exes

Prakash Nadar4-Mar-04 21:59

Prakash Nadar

4-Mar-04 21:59

one thing i would do is that open the exe or the dll with dependency walker and find anything that depends on debug dlls like mfc42d.dll or mfc42ud.dll if it does then this binary was build in debug version.

Re: Detect Debug Exes

bilal789-Mar-04 18:01

bilal78

9-Mar-04 18:01

Well if you want, you can search on the net for Windows PE file Specification, and according to it ".exe" file compiled with debug information will have ".debug" section. If you find this section, this means your ".exe" file has dubug information included.

Best Regards,
Bilal Anjum

Messages from the service control manager

JensB4-Mar-04 21:23

JensB

4-Mar-04 21:23

Hi,

I have still two little questions.
I can restart, stop, pause the application by using the service control manager. Are there somehow some messages sent to the program so i can do some additional work . (for example, reboot a service which is minimised to the task bar .. two icons in the task bar) If you move with your cursor above it, one will disappear. But it is not nice to see two icons

Greetings,
Jens

HINSTANCE inst = AfxGetInstanceHandle();

akirachen4-Mar-04 21:22

akirachen

4-Mar-04 21:22

執行這一行
HINSTANCE inst = AfxGetInstanceHandle();

會停在
MFC\Include\AFXWIN1.INL

_AFXWIN_INLINE HINSTANCE AFXAPI AfxGetInstanceHandle()
{ ASSERT(afxCurrentInstanceHandle != NULL);
return afxCurrentInstanceHandle; }

好像afxCurrentInstanceHandle是NULL的關係
這是因為什麼原因?
是我少Call什麼Function嗎?(win32 application project)

Re: HINSTANCE inst = AfxGetInstanceHandle();

Iain Clarke, Warrior Programmer5-Mar-04 3:28

Iain Clarke, Warrior Programmer

5-Mar-04 3:28

You are more likely to get an answer if you ask the question in English.

Lots of people here can read bad english. Not as many people can read chinese.

Try again!

Iain.

How to change the account type of current logged on user thru my application?

.NetRams4-Mar-04 20:35

.NetRams

4-Mar-04 20:35

Hi,
Help me to change the account type of current user in Windows XP dynamically through my application. (ie. Normal user to Administrator or viceversa)
Provide me is there any demo projects to download...

Thanks in Advance Rose | [Rose]

iRams

Re: How to change the account type of current logged on user thru my application?

Mazdak4-Mar-04 21:09

Mazdak

4-Mar-04 21:09

NetUserSetInfo function. There is a sample in MSDN for it.

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

Re: How to change the account type of current logged on user thru my application?

.NetRams5-Mar-04 1:12

.NetRams

5-Mar-04 1:12

Can anyone tell me why NetUserSetInfo gives an error when using the
structure USER_INFO_1005 . The error value is 87 and the value of the
last parameter of the function is 997.Any idea about it.. Confused | :confused:

Here is the code, I need to change the current Login User with Normal Rights to Administrator rights.

char lpBuffer[255];

USER_INFO_1005 usriPriv;
DWORD netRet = 0;

usriPriv.usri1005_priv = USER_PRIV_ADMIN;

netRet = NetUserSetInfo( NULL, (unsigned short *)lpBuffer, 1005, (LPBYTE)&usriPriv,NULL);

if( netRet == NERR_Success )
printf("Success!\n");
else
printf("ERROR: %d Returned from NetUserSetInfo\n", netRet);

Re: How to change the account type of current logged on user thru my application?

Steve S7-Mar-04 22:42

Steve S

7-Mar-04 22:42

Hint: Error 87 = "The parameter is incorrect".

1. You aren't specifying a server, so this will assume that the lpBuffer is an account name on the local machine.
2. Is the executing account sufficiently privileged (see docs on NetUserSertInfo).
3. When you say the value of the last parameter is 997, have you tried testing it against values like USER_PRIV_INFOLEVEL or USER_PRIV_PARM?
(How do you know it's 997, you're passing in NULL, so it doesn't give you the value?)

Steve S

Multiple Controls One Handler

monrobot134-Mar-04 20:28

monrobot13

4-Mar-04 20:28

I've done some work with C# and one of the things I really like was the fact that I could have the same handler for many different controls on a form. For example if I had five buttons and an event handler called OnButtonClick I could setup every button to call that same handler. Is it possible to do something like this in MFC? If so how? I have a bunch of edit controls that all need to do the same processing after losing focus and I'd rather have one function for them all instead of having to have a bunch of handlers that do that exact same thing. Thanks in advance for the help.

I just thought of something...would this be as simple as adding a message map entry to map the edit boxes I want to use the function to that function?

BEGIN_MESSAGE_MAP(CMyDialog, CDialog)
    ON_EN_KILLFOCUS(IDE_BOX1, OnKillFocusEdit)
    ON_EN_KILLFOCUS(IDE_BOX2, OnKillFocusEdit)
    ON_EN_KILLFOCUS(IDE_BOX3, OnKillFocusEdit)
    ON_EN_KILLFOCUS(IDE_BOX4, OnKillFocusEdit)
END_MESSAGE_MAP()

Would that work? Just thought of something else. If that did work how would I know which edit box called the function?

Thanks

- monrobot13

Re: Multiple Controls One Handler

Michael Dunn4-Mar-04 20:54

Michael Dunn

4-Mar-04 20:54

Yeah, you can have one handler handle as many messages as you like. To get the HWND of the caller, you'll need to look at the LPARAM of the message, which for WM_COMMAND is the HWND of the control that sent the message: GetCurrentMessage()->lParam

--Mike--
Personal stuff:: Ericahist | Homepage
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Re: Multiple Controls One Handler

monrobot135-Mar-04 6:04

monrobot13

5-Mar-04 6:04

Michael Dunn wrote:
which for WM_COMMAND is the HWND of the control that sent the message

Is this the same for WM_KILLFOCUS?

Thanks for the help

- monrobot13

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