C / C++ / MFC Discussion Boards

George Ma30-Aug-02 18:35

30-Aug-02 18:35

Hi, everyone!

Please look at the following statement,

--------
#define assert(x) ((void)0)
--------

What does the statement mean? What is the function
of "((void)0)" here?

Another question, there is a paramater "x" in the former
"assert(x)", why there is not a parameter in the latter
"((void)0)"?

Cheers,
George

Re: A question about #define

Renjith Ramachandran30-Aug-02 19:48

Renjith Ramachandran

30-Aug-02 19:48

i think
in this macro,if u pass a variable containing a value;and then here u put ((void)0),that will show an ASSERTION FAILURE.!!! dialog..

DWORD dwmydw = 4567 ;
asert(dwmydw ) will show the assertion failure dialog..

Renjith-CPian.

Re: A question about #define

George Ma30-Aug-02 21:17

George Ma

30-Aug-02 21:17

Thanks, Renjith pal!

I think your case is correct. But I think
the function of the statement is not to
invoke the assert failure dialog box. Smile | :)

What is the funciton of the statement? I
have seen a lot of cases that the same
statement is using.

Cheers,
George

Re: A question about #define

Todd Smith30-Aug-02 20:32

Todd Smith

30-Aug-02 20:32

((void)0) will compile to nothing. You usually see something like this

#ifdef _DEBUG
#define assert(x) some_assert_function(x)
#else
#define assert(x) ((void)0) // make assert become nothing
#endif

so that assert's are only enabled in debug builds.

Todd Smith

Re: A question about #define

George Ma30-Aug-02 21:20

George Ma

30-Aug-02 21:20

Thanks, Todd pal!

Your reply has clarified all my doubts.

Have a nice weekend,
George

Dialog Bars and Buttons

Chun Te, Ewe30-Aug-02 13:18

Chun Te, Ewe

30-Aug-02 13:18

Dear All,

I hope anyone can help me out with this seeming simple problem.
I've implemented a dialog bar with buttons on them which I would like to disable them from time to time. I've used
m_wndDlgBar.GetDlgItem(IDC_BUTTON1)->EnableWindow(FALSE);
and it wouldn't work.
I even disabled it with the resource editor.

Thanks very much for your precious time.

Regards
CT

I'm sorry but other question about Carlos Antollini ADO classes !

Hadi Rezaee30-Aug-02 12:49

Hadi Rezaee

30-Aug-02 12:49

Hi there !
It's Hadi with other question about ADO classes Poke tongue | ;-P

Well, as all of you know ... when you use FindFirst or FindNext, ado engine move the recordset to new record if the record finded ...
My problem is about m_Rs.Find( string, CADORecordset::searchBackward );
This function works well when it find a record but it DOESN'T MOVE the recordset to finded record Confused | :confused:

What's wrong ?
How can i move the recordset to finded record when i'm using Find( string, CADORecordset::searchBackward ); ???

Regards

My month article: Game programming by DirectX by Lan Mader.
Please visit in: www.geocities.com/hadi_rezaie/index.html

Hadi Rezaie

sound output

Nnamdi Onyeyiri30-Aug-02 12:12

Nnamdi Onyeyiri

30-Aug-02 12:12

lets say i have some audio information that i want to output, can anyone point me in the right direction?

Thanks.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Re: sound output

Anders Molin30-Aug-02 12:27

Anders Molin

30-Aug-02 12:27

sndPlaySound() if it's a wavefile... (Or a wavefile from a resourcefile)

- Anders

Money talks, but all mine ever says is "Goodbye!"

Re: sound output

Nnamdi Onyeyiri30-Aug-02 23:28

Nnamdi Onyeyiri

30-Aug-02 23:28

i was thinking more along the lines of i have the sound data and need to output it Smile | :)

- i thought it'd be interesting to know how it is done.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Writing app to tell others what game server I am connected to. Need advice.

Raskolnikov30-Aug-02 12:13

Raskolnikov

30-Aug-02 12:13

I am a proficient C++ programmer and am familiar with Win 32 Api programming, but am just learning MFC.

I want to write an MFC application that will detect which America's Army Server I am connected to, create an updated webpage and then upload that page via ftp to my websever.

What do I need to learn in order to
a) detect the ip and port numbers to which I am connected.
b) log on to an ftp sever and upload a file.

I could probably do this with dos commands using netstat and a comand line ftp app, but I would rather not.

Re: Writing app to tell others what game server I am connected to. Need advice.

Michael P Butler30-Aug-02 22:15

Michael P Butler

30-Aug-02 22:15

Search on MSDN for the Winsock and sockets. This should give you a starting point for reading about IP comms.

Michael Smile | :)

Programming is great. First they pay you to introduce bugs into software. Then they pay you to remove them again.

tree

yaser30-Aug-02 11:16

yaser

30-Aug-02 11:16

i want to simulate workspace in vc++,i use CTree on the CDialogBar.i want to if select the item that opened active else run OnNewFile.Please Help me

Re: tree

Pole30-Aug-02 21:50

Pole

30-Aug-02 21:50

Send message to your main view,when user selected the tree item.

Sincerely,Pole.

Tree

yaser30-Aug-02 11:01

yaser

30-Aug-02 11:01

i want to simulate workspace in vc++,i use CTree on the CDialogBar.i want to if select the item that opened active else run OnNewFile.Please Help me

tree

yaser30-Aug-02 10:52

yaser

30-Aug-02 10:52

i want to simulate workspace in vc++,i use CTree on the CDialogBar.i want to if select the item that opened active else run OnNewFile.Please Help me
Confused | :confused:

NTService creating COM object problem

Ed K30-Aug-02 9:26

Ed K

30-Aug-02 9:26

I have a small logging utility that I use across several different applications. When I try to use it from withing an NT Service I can't get any logging. Any gotchas you've run across regarding using COM from an NT Service?

Thanks,

ed

Re: NTService creating COM object problem

Vagif Abilov30-Aug-02 10:12

Vagif Abilov

30-Aug-02 10:12

In general, there is nothing that prevents COM components from being used in NT services. There are some issues you should know:

1. NT services run in a special account that don't interact with user, so if your component tries to display a message box, you're out of luck. Moreover, if you happen to use some MFC classes that cause assertion, they will end up (at least in DEBUG mode) displaying message box that will stop the service (of course without displaying anything).

2. Be careful with use of MFC user interface classes (in other words, don't use them). You can use MFC collection, thread and string classes.

The easiest way to discover what's wrong is to debug your service (select its process in task list, right-click and choose "debug").

Hope this helps.

Vagif Abilov
MCP (Visual C++)
Oslo, Norway

If you're in a war, instead of throwing a hand grenade at the enemy, throw one of those small pumpkins. Maybe it'll make everyone think how stupid war is, and while they are thinking, you can throw a real grenade at them.
Jack Handey, Deep Thoughts

Re: NTService creating COM object problem

Ed K30-Aug-02 11:13

Ed K

30-Aug-02 11:13

I don't use any user interface. I have a separate control panel applet that handles that. Working on the debugging though...

Thanks,

ed

Re: NTService creating COM object problem

Le centriste30-Aug-02 10:20

Le centriste

30-Aug-02 10:20

That may sound silly, but did you call CoInitialize?

Also, if you want to see pop-ups from your NT service, you choose "Interact with desktop" check box for the "LogON" tab in the service properties. That way, you may see any assertion failed dialog boxes.

Michel

It is a lovely language, but it takes a very long time to say anything in it, because we do not say anything in it, unless it is worth taking a very long time to say, and to listen to.

- TreeBeard

Re: NTService creating COM object problem

Ed K30-Aug-02 11:08

Ed K

30-Aug-02 11:08

I did. I use a little struct (below - found somewhere??) to initialize and uninitialize.

<br />
struct CComInit {<br />
	CComInit() { CoInitialize(NULL);  }<br />
	~CComInit() { CoUninitialize(); }<br />
};<br />

Then during initialization:

<br />
CComInit comInit;<br />

Thanks...

ed

Re: NTService creating COM object problem

Jörgen Sigvardsson30-Aug-02 11:52

Jörgen Sigvardsson

30-Aug-02 11:52

If you're compiling an ATL com server, be sure to see if you've got ATL_MINCRT defined. (I think that's the right name..)

IIRC, global object constructors are not called if you use this optimization since the libc is not there to do it for you...

Preferred storyline:
- I am your father. Search your feelings and you'll know it's the truth. Together we can rule this galaxy like father and son.
- Ok dad. Let's kick some butt!

Re: NTService creating COM object problem

Anders Molin30-Aug-02 12:32

Anders Molin

30-Aug-02 12:32

I have used a lot of COM from services, and have never had a single problem with it.

Just remember that if you write your log to a shared directory on another computer, the default account a service is running under (Local System) don't have access to network resources...

What happens?
Do you create the COM object successfully?

If you have written the COM object yourself, you might use some TRACE in the object so you can see what happens...

- Anders

Money talks, but all mine ever says is "Goodbye!"

position of code matters?

ns30-Aug-02 9:23

30-Aug-02 9:23

I had in my OnInitialUpdate this fragment at the end of the function:

 if(NULL != m_THBImage1.GetSafeHwnd())

{
    m_THBImage1.MoveWindow(10,10,200,180);
    m_THBImage2.MoveWindow(10,200,200,180);
    m_THBImage3.MoveWindow(10,390,200,180);
    m_THBImage4.MoveWindow(10,580,200,180);

}

Well, the code would run and never go into the block, so that my controls were higgledy piggledy on the screen. I moved it to the start of the function, and it works (though one time it crashed and didnt move the imageboxes). I am uneasy about why the crash and why the relocation works.

Most of the code in the OnInitialUpdate function does database access and sets things up.

The same relocation trick worked for the following in the same function:

if(NULL != m_listdisplay.GetSafeHwnd())

{
m_listdisplay.SetExtendedStyle(LVS_EX_CHECKBOXES);
m_listdisplay.InsertColumn(0,"Options",LVCFMT_LEFT,800);
}

If it was at the end of the function, my listctrl would come up blank with no columnheader, and when moved up, its okay.

The one time it crashed (even after moving the code up), the list ctrl was blank and there was no columnheader. I cant reproduce it but am extremely nervous.

Appreciate your insight.
Thanks,
ns Confused | :confused:

Re: position of code matters?

Ravi Bhavnani30-Aug-02 12:32

Ravi Bhavnani

30-Aug-02 12:32

Seems like you're returning before it can get to the code. A TRACE statement could verify this.

ns wrote:
higgledy piggledy
I have to add this term to my glossary. Smile | :)

/ravi

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

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