C / C++ / MFC

Neville Franks9-Oct-04 12:43

Neville Franks

9-Oct-04 12:43

Run the program under the VC++ Debugger and when the ASSERT occures press Retry to go into the debugger. Then look at the Stack Backtrace to find the cause.

Threads should be closed properly by your code. There are several waits to do this. One is to wait on an Event that you signal when your app is closing. Another is to force the thread to raise an exception. See: http://www.codeproject.com/threads/threadlibrary.asp [^] for a good example of this.

I have to wonder why your thread is posting a message once a second and what the thread is being used for. Threads shouldn't be an infinite loop. They should either Wait or Exit when processing is complete.

Neville Franks, Author of ED for Windows www.getsoft.com and Surfulater www.surfulater.com "Save what you Surf"

Leyu10-Oct-04 7:51

Leyu

10-Oct-04 7:51

Neville Franks wrote:
I have to wonder why your thread is posting a message once a second and what the thread is being used for. Threads shouldn't be an infinite loop. They should either Wait or Exit when processing is complete.

First I wanted to make a thread to post a message each second because i was not satisfied with windows timer WM_TIMER messages i wanted to make a timer that is more or less accurate and won't be affected by other messages placed in the queue such as fast mouse cliks or so.

Neville Franks wrote:
Run the program under the VC++ Debugger and when the ASSERT occures press Retry to go into the debugger. Then look at the Stack Backtrace to find the cause.

The main problem is the Dialog box saying i have a debug assertion failure is displayed for a very short time and boom!!! it goes. i could not even see what the error message. let alone to push the button retry, i tired to capture the screen when the dialog box is displayed and it was to fast to do so by pressing the print screen key on the key board.
The debug assertion is caused when i close the window and especially for the first time i boot my comupter and run it from the VC++ editor, after the first build it occurs occasionaly

Neville Franks10-Oct-04 10:22

Neville Franks

10-Oct-04 10:22

leyusha wrote:
Neville Franks wrote:
I have to wonder why your thread is posting a message once a second and what the thread is being used for. Threads shouldn't be an infinite loop. They should either Wait or Exit when processing is complete.

First I wanted to make a thread to post a message each second because i was not satisfied with windows timer WM_TIMER messages i wanted to make a timer that is more or less accurate and won't be affected by other messages placed in the queue such as fast mouse cliks or so.

This makes little sense to me. If your thread is using PostMessage() then you have no better gaurantee of the timer message being received at a specific time than WM_TIMER messages.

leyusha wrote:
The main problem is the Dialog box saying i have a debug assertion failure is displayed for a very short time and boom!!!

I would say you have a serious problem somewhere (not helpfull I know). I'd set a breakpoint in the debugger in the MFC ASSERT code that opens the message box. I'd also have a close look at the thread function. Maybe it is Posting to a Window that no longer exists. Multithreading is a complex area and should be avoided unless you have a very good understanding of how it all works.

Neville Franks, Author of ED for Windows www.getsoft.com and Surfulater www.surfulater.com "Save what you Surf"

Leyu12-Oct-04 7:07

Leyu

12-Oct-04 7:07

Neville Franks wrote:
Maybe it is Posting to a Window that no longer exists

Yeap u are right i added a sleep function in the destructor of CView and was able to see the "ASSERT falure dialog box" and saw the file and line number with the assertion failure it seems that the CWnd::PostMessage() first checks to see if the CWnd is valid and hey it fails there.

Thanks a lot (now i have added a volatile bool variable to exit loop and a check to see if the CWnd is valid before posting a message and if not to exit loop)

Drawline fucntion?

Tommy2k9-Oct-04 6:33

Tommy2k

9-Oct-04 6:33

Is there any function to draw draw a line with GDI? I can't seem it..:S

Ravi Bhavnani9-Oct-04 6:42

Ravi Bhavnani

9-Oct-04 6:42

LineTo()

/ravi

My new year's resolution: 2048 x 1536
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Tommy2k9-Oct-04 6:47

Tommy2k

9-Oct-04 6:47

yeah i saw that function but it only lets me set 1 point.. not 2:s...

Ravi Bhavnani9-Oct-04 6:54

Ravi Bhavnani

9-Oct-04 6:54

You need to MoveTo() first. Smile | :)

/ravi

My new year's resolution: 2048 x 1536
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Getting the Audio Stereo Mixer or Line In Input

Tommy2k9-Oct-04 7:09

Tommy2k

9-Oct-04 7:09

Thank you very much Smile | :)

Nikhil Wason9-Oct-04 5:38

Nikhil Wason

9-Oct-04 5:38

I wanna make a standalone audio visualization. For that i would need the waveform or the amplitude of samples of the audio being played.

Is there ne way in which i can get the waveform or the amplitudes of samples of the media playing on the computer through stereo mixer and/or line-in??

This is similar to the way sound recorder can record ne audio being played by any application on the computer.

Pls hlp.

--
Nikhil

how do i export multiple functions in dll

Lanre Ogunkola9-Oct-04 5:22

Lanre Ogunkola

9-Oct-04 5:22

i already have a dll i could call up from a vb application but i would want to export multiple functions from the c++ dll. anyone got ideas

thanks

larry_larry

larry_larry

Re: how do i export multiple functions in dll

Abbas_Riazi9-Oct-04 6:47

Re: how do i export multiple functions in dll

9-Oct-04 6:47

It is very simple. Just create a regular dll and export as much as functions that you want:

#define DLLEXPORT __declspec(dllexport)

DLLEXPORT int func1()
{
    //....
    return 0;
}

DLLEXPORT void func2()
{
}

DLLEXPORT void func3()
{
}

A. Riazi

Abbas_Riazi9-Oct-04 6:51

return values from exported functions in dll

9-Oct-04 6:51

Also see these Articles:
- DLLs are simple - Part I[^]
- DLLs are simple - Part II[^]
- DLLs are simple - Part III[^]

A. Riazi

Lanre Ogunkola10-Oct-04 3:39

Lanre Ogunkola

10-Oct-04 3:39

Thanks a milll Riazi. But i am also having problems exporting strings from the dll. the only thing that seems to work is if i put the string value in a
messagebox

CString myString()
{
char exString[10] = "Hellodarling"
AfxMessageBox( exString )
return exString
}

this usually give an error of === bad dll call when i call it up in vb
while the message box will display the exstring... and if i change the definition of exstring to == CString exstring it also give an error...
what do think

larry_larry

Re: return values from exported functions in dll

Abbas_Riazi10-Oct-04 3:44

Re: return values from exported functions in dll- errors

10-Oct-04 3:44

Strings in VB are differ from VC. Use BSTR instead of CString.

A. Riazi

Lanre Ogunkola11-Oct-04 6:23

Lanre Ogunkola

11-Oct-04 6:23

BSTR sTittle()
{
CString s = _T("dllretval");
double d = atof (s);
return s;
}

error C2440: 'return' : cannot convert from 'class CString' to 'unsigned short *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
Error executing cl.exe.

BSTR sTittle()
{
BSTR s = "dllretval";
return s;
}

error C2440: 'initializing' : cannot convert from 'char [9]' to 'unsigned short *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe.

larry_larry

Ethernet Commands

harios9-Oct-04 4:46

harios

9-Oct-04 4:46

I was wondering if anybody could tell me where to find a ports list for controling the ethernet card. That or some code showing how to change the cards mac address? The ports would be better.

in ports in meen asm ports

out F8,ax

4r3 j00 L33+

Abbas_Riazi9-Oct-04 7:08

9-Oct-04 7:08

I think you can't change the MAC address of a card. The MAC placed on the card by it's manufacturer.

A. Riazi

FASTian10-Oct-04 5:15

FASTian

10-Oct-04 5:15

sure you can change the mac address....search for it on the web and you'll find applications like SMac which you can use to change the mac address for your ethernet card.

Abbas_Riazi10-Oct-04 5:19

10-Oct-04 5:19

If I changed the MAC address of my network card to one that exist in a LAN, what happened? Also, is it possible to change MAC address of DVB cards?

A. Riazi

Henry miller11-Oct-04 3:33

Henry miller

11-Oct-04 3:33

If you change your Mac Address to something that exists, bad things can happen. Exactly what depends on many things. If you never transmit, and you have a switched network nothing will happen. If you have hubs, then you will see all traffic for the other machine as if it went to yours. (better to tell the card to listen for everything if you want to do this though)

If you transmit you mess up the network, and the sys admin will be down your throat. Don't do it.

Nearly all[1] cards support changing the Mac Address from software. DecNet requires this ability. Everyone is afraid that the last person on earth who runs DecNet will buy their card and it won't work. Besides, because everything ethernet has always supported changing the Mac Address, it is easier to leave that in each upgrade than to take it out.

I don't know what a DVB card is, so I can't speak for that particular case.

[1]It is probably safe to just say all. I know of no exceptions and find them unlikely.

Abbas_Riazi11-Oct-04 7:41