C / C++ / MFC

Re: Application crashes only in release mode (possible heap/stack corruption)

9-Dec-10 13:11

How would i do that Smile | :)

By the way, it is ecx that contains a rather large number, which is causing the expression to access invalid memory. So i imagine that ecx should normally contain a valid value.

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Luc Pattyn9-Dec-10 13:16

Re: Application crashes only in release mode (possible heap/stack corruption)

9-Dec-10 13:16

based on the virtual address.

Smile | :)

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XTAL2569-Dec-10 17:48

Re: Application crashes only in release mode (possible heap/stack corruption)

9-Dec-10 17:48

Sorry, i still don't know what you are talking about. You seem to be saying that there is a way to find the function which that line of code is in. While i understand that it may technically be possible, i have no idea how to do it.

btw, thanks to everyone else who replied.

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Luc Pattyn9-Dec-10 22:47

Re: Application crashes only in release mode (possible heap/stack corruption)

9-Dec-10 22:47

research this[^]

XTAL256 wrote:
thanks to everyone else

No thanks then.

Smile | :)

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XTAL2569-Dec-10 23:21

Re: Application crashes only in release mode (possible heap/stack corruption)

9-Dec-10 23:21

Well, i was going to thank you once you clarified your previous post. But since you gave me the lmgtfy response, i don't think i will Smile | :)

. Just kidding.

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Rajesh R Subramanian9-Dec-10 17:26

Rajesh R Subramanian

9-Dec-10 17:26

Please read this: Surviving the release version[^]

It was ever thus, the Neophiles will always rush out and get 'The Latest Thing' at a high price and with all the inherent faults - Dalek Dave.

Re: Application crashes only in release mode (possible heap/stack corruption)

XTAL25612-Dec-10 12:09

12-Dec-10 12:09

fyi, i found the problem. I stupidly forgot to return a value from a function. I only just picked it up then when the compiler told me that "not all control paths return a value". I guess i missed that warning previously.

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C Casting Problem

Andy2029-Dec-10 8:14

Andy202

9-Dec-10 8:14

I have seen the term Fixed_32 for a data item with MSB = 1 and LSB = 1/2**31 ;
Max = 1.0 and Min = -1.0 with units of semicircles (used for Latitude and Longitude)

I did think this was a float to the IEEE-754 Floating-Point Representation.
However the 3rd party that is reading some data via a message structure cannot see the same value.
I mistaken the term Fixed_32 as a standard float but it is a 32 bit int in the message.

The scalling is:-

#define	BEARING_SCALING          	4.65661287307739E-10 

typedef struct ReceiveMessage
{
    unsigned int msgNumber;      // Msg number
    int             msgPosLat;      // Msg latitude
    int             msgPosLong;     // Msg longitude
    unsigned int msgQuality;     // Msg quality
}positionData

#define	BEARING_SCALING          	4.65661287307739E-10

However I get a crash when I try to load the value (the Latitude was declared as a double and I tried to cast to the int and vice versa.

Code:

// Note 180 is used to scale up from semicircles to degrees
double lat = 55.55;
positionData.msgPosLat = (int)(lat/(BEARING_SCALING * 180));

// and the other way for reading:-

 lat = (double)( positionData.msgPosLat) * BEARING_SCALING * 180;

What is going wrong please, is it the oder of casting or do I need to use fix point stuff?

Re: C Casting Problem

Luc Pattyn9-Dec-10 9:01

Re: C Casting Problem [modified]

9-Dec-10 9:01

I think it works like this:

the latitude in degrees ranges from -90 to +90 (and not -180 to +180).
the encoding used is 32-bit fixed integers with an implied scale factor, so the full range [-90,+90] gets mapped onto the full integer range.
So you want +90 represented by the largest positive 32-bit integer (which equals 2^31 minus one, or 0x7FFFFFFF), hence:

int fixed32(double lat) {
    lat=lat/90.;
    lat=lat*0x7FFFFFFF;
    return (int)lat;
}

Notes:

1. this code will never return the minimum value (0x80000000). For -90 it results in 0x80000001 which is a consequence
of [-90,+90] being symmetric around zero, whereas the integer range [0x80000000, 0x7FFFFFFF] isn't.

2. I tend to avoid magic constants, such as the 4.65661287307739E-10 you had. I prefer to write them in a way that reveals what they stand for. Your value stems from 1.0/0x7FFFFFFF

3. I doubt the code you have shown would crash at all.
lat/(BEARING_SCALING * 180) will not exceed the acceptable range for integers (and your formula being wrong by a factor of 2 IMO only reassures this).
(positionData.msgPosLat) * BEARING_SCALING * 180) may incur an integer overflow (again due to the factor of 2), but normally those get swallowed.
So I expect if anything bombs, it must be the code that follows after you used these formulas, mainly the latitude going all the way up to +180.

Smile | :)

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modified on Thursday, December 9, 2010 3:45 PM

Re: C Casting Problem

Andy2029-Dec-10 10:41

Andy202

9-Dec-10 10:41

Thanks Luc, the Longitude (-180 to +180) has the same scaling.

I can get the code running OK on Windwos but when ported to Unix (using a Gnu complier) the program bombs out.
Debuggin a bit limited hence the use of Windows for the development.

Luc Pattyn9-Dec-10 11:06

9-Dec-10 11:06

Andy202 wrote:
the Longitude (-180 to +180) has the same scaling.

not sure what you are saying here. the longitude range has to cover 360 degrees (either -180 to +180 or 0 to +360), so it could be latitude uses the same scale factor, but then your opening statement (about MIN and MAX) isn't accurate for latitude.
OTOH if the scale factor is different for lat and lon, that would justify why the 180 (or 360) isn't incorporated in the magic constant.

Andy202 wrote:
when ported to Unix (using a Gnu complier) the program bombs out.

A different compiler may generate different code, e.g. it could emit code that does check for overflows at run-time.
[ADDED] So far you have not specified where in the code it crashes. [/ADDED]

I can only suggest you:
1. include some logging statements so you can watch the numbers till the program crashes.
2. perform some unit tests (a simple loop over the range of interest should be easily implemented).

Taken together, that will clarify what goes on.

Smile | :)

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modified on Thursday, December 9, 2010 5:17 PM

Re: C Casting Problem

mbue9-Dec-10 12:07

Save image from picturebox use MFC

9-Dec-10 12:07

normally c-compilers cast from left to right (implicit). if yours don't - cast yourself (explicit):

positionData.msgPosLat = (int)(lat/(BEARING_SCALING * 180.0));
// (int)(double/(double*double))
AND
lat = ( (double)positionData.msgPosLat * (BEARING_SCALING * 180.0));
// (double*(double*double))

// hint: don't define twice (BEARING_SCALING)

have a nice day.

josipahutar9-Dec-10 8:02

9-Dec-10 8:02

hi guys,,,
i'm a newbie in MFC so i'm need your advice to complete final project about identification signature. in this time i have problem about how to save image from picture box in MFC. this is my code used in MFC. this code not save image from picturebox. what's wrong with my code???

void SaveBitmapToFile( BYTE* pBitmapBits, LONG lWidth, LONG lHeight,WORD wBitsPerPixel, LPCTSTR lpszFileName );

void CSaveimageDlg::OnSave()
{
// TODO: Add your control notification handler code here
CDC *pDC = m_pic1.GetDC();
CDC dcMem1;
CRect rect;
m_pic1.GetClientRect(rect);
HDC hdc;
HBITMAP hBitmap = NULL;
BITMAP bm;

CBitmap Bitmap;
m_pic1.SetBitmap(Bitmap);
Bitmap.CreateBitmap(200 ,200,1,24,NULL);
m_bmpBitmap.GetBitmap(&bm);
//Bitmap.GetBitmap(&bm);
Bitmap.GetObject( sizeof( BITMAP ), &bm );

unsigned char *pData = new unsigned char [bm.bmHeight*bm.bmWidthBytes];
SaveBitmapToFile(pData,bm.bmHeight,bm.bmWidth,24,(LPCTSTR)_T("a.bmp"));
delete []pData;
}

void CSaveimageDlg::SaveBitmapToFile(BYTE *pBitmapBits, LONG lWidth, LONG lHeight, WORD wBitsPerPixel, LPCTSTR lpszFileName)
{
BITMAPINFOHEADER bmpInfoHeader = {0};
bmpInfoHeader.biSize = sizeof(BITMAPINFOHEADER);
bmpInfoHeader.biBitCount = wBitsPerPixel;
bmpInfoHeader.biClrImportant = 0;
bmpInfoHeader.biClrUsed = 0;
bmpInfoHeader.biCompression = BI_RGB;
bmpInfoHeader.biHeight = lHeight;
bmpInfoHeader.biWidth = lWidth;
bmpInfoHeader.biPlanes = 1;
bmpInfoHeader.biSizeImage = lWidth* lHeight * (wBitsPerPixel/8);

BITMAPFILEHEADER bfh = {0};
bfh.bfType=0x4D42;
bfh.bfType = 'B'+('M' << 8);
bfh.bfOffBits = sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER);
bfh.bfSize = bfh.bfOffBits + bmpInfoHeader.biSizeImage;

HANDLE hFile = CreateFile( lpszFileName,GENERIC_WRITE, 0,NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,NULL);

if( !hFile ) // return if error opening file
{
return;
}

DWORD dwWritten = 0;
WriteFile( hFile, &bfh, sizeof(bfh), &dwWritten , NULL );
WriteFile( hFile, &bmpInfoHeader, sizeof(bmpInfoHeader), &dwWritten, NULL );
WriteFile( hFile, pBitmapBits, bmpInfoHeader.biSizeImage, &dwWritten, NULL );
CloseHandle( hFile );
}

mbue9-Dec-10 12:16

9-Dec-10 12:16

1.) width != byte_width! byte_width == (width*(bitsperpixel/8)+3)&~3 (4byte boundary)
2.) call GetBitmapBits to get the bitmap content before save.
have a nice day.

tagopi9-Dec-10 17:08

tagopi

9-Dec-10 17:08

Hello

Try this.

http://www.ucancode.net/Visual_C_Codes/MFC-Example-CreateFile-WriteFile-save-memory-dc-bitmap-file.htm

instead of memdc, you can call your picture box dc.

Thanks
A. Gopinath.

josipahutar11-Dec-10 7:27

11-Dec-10 7:27

thx for your answer sir..
but after i try the code, i can't find image c://temp.bmp.
can u tell me , how to the code work in MFC to save a image di picturebox.

my problem : i will load a image to picturebox in MFC then i'm want to save it.
can u give sample code about my problem??

Regard's
Johannes.

josipahutar11-Dec-10 7:38

11-Dec-10 7:38

Thx sir..

but i dont understand..
Can you explain in detail the program...

Regard
Johannes

tagopi12-Dec-10 17:08

tagopi

12-Dec-10 17:08

Hello

try by sending this hDC to save. I didn't tried this. check whether it is working or not.
HDC hDC=GetDC(GetDlgItem(IDC_PICTUREBOX); //------- id for your picture box.

Save...... (hDC, ...);

Thanks
A. Gopinath.

josipahutar13-Dec-10 7:29

13-Dec-10 7:29

sir, i got a error.. "GetDC' : function does not take 1 parameters"

how about it??

890918 - keystroke seems not to generate the desired command

tagopi16-Dec-10 16:45

tagopi

16-Dec-10 16:45

Hello,

sorry for delay. instead of HDC you can use CClientDC. that will work.

Regards,
A. Gopinath.

ilostmyid29-Dec-10 6:45

ilostmyid2

9-Dec-10 6:45

hi i defined an accelerator Ctrl+T to generate ID_TMPDLG. i put

ON_COMMAND(ID_TMPDLG, &Ct2App::OnTmpDlg)

but the function is not called. i tried to see whether to message for the accelerator is generated correctly and i tested it in:

BOOL Ct2App::PreTranslateMessage(MSG* pMsg)
{
	// TODO: Add your specialized code here and/or call the base class
	if (pMsg->message == WM_KEYDOWN && pMsg->wParam == 'T')
		return CWinAppEx::PreTranslateMessage(pMsg);
	return CWinAppEx::PreTranslateMessage(pMsg);
}

by defining a break point, i realized that the line is hit and the message is produced correctly. but i don't know why the command ID_TMPDLG is not generated or received by the application. i tried to handle the command in another places like main frame and child view, but it didn't help and the command is not still generated or received. i don't know whether the accelerator message is not converted into the command or the message is lost somewhere.
what can i do?
thx

Re: 890918 - keystroke seems not to generate the desired command

mbue9-Dec-10 12:25

Re: 890918 - keystroke seems not to generate the desired command

9-Dec-10 12:25

1.) create an accelerator resource.
2.) load them: _haccel = LoadAccelerator(0,MAKEINTRESOURCE(<idaccel_res>))
3.) translate them by calling TranslateAccelerator()
have a nice day.

ilostmyid210-Dec-10 3:53

ilostmyid2

10-Dec-10 3:53

oh thanx
so u mean my defined accelerator is not loaded or is not translated?
i put it in the only one pre-existing accelerator list with the id of IDR_MAINFRAME. if it's not loaded the other defined accelerators in the list must also not work, but they do. for example Ctrl+S brings up the Save As dialog, etc.
how can i justify this and how can i check that whether an accelerator is loaded or translated properly and where in the program does this happen?
thx

Re: 890918 - keystroke seems not to generate the desired command

mbue10-Dec-10 8:59