Re: Heap Corruption - C / C++ / MFC Discussion Boards

yaminisridaran5-Aug-07 21:22

5-Aug-07 21:22

I am getting heap corruption

Code:

BYTE *Image=NULL;
Image=(unsigned char *)malloc(50000);
Image=Dlg.CaptureImage();
free(Image);

Plz Help me

S.Yamini

Re: Heap Corruption

Sam_c5-Aug-07 22:47

Sam_c

5-Aug-07 22:47

do a check on the size of the image, you might not be allocating enough space?

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Re: Heap Corruption

yaminisridaran5-Aug-07 22:49

yaminisridaran

5-Aug-07 22:49

I changed the size to 5000000.Still I am getting heap corruption when i am trying to delete the BYTE pointer.Suggest me some ways to solve the issue

S.Yamini

Re: Heap Corruption

Sam_c5-Aug-07 23:00

Sam_c

5-Aug-07 23:00

how does Dlg.CaptureImage() return the image data?

by value?

i'm not sure about the error if that isnt the problem.
would need to have access to a compiler which i dont at the moment Sigh | :sigh:

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Re: Heap Corruption

yaminisridaran5-Aug-07 23:31

yaminisridaran

5-Aug-07 23:31

I use delete to free the memory but when i execute delete the exection goes to winheap

S.Yamini

Re: Heap Corruption

jk chan6-Aug-07 0:36

jk chan

6-Aug-07 0:36

Check the return pointer of CaptureImage , is that the same as the orginal (before calling CaptureImage ). Also Try Debugging CaptureImage. the problem is ur trying to delete a pointer which is not a valid head head. it can also happen in these case

int * p = malloc(100);
p+= nSomeValueLessthan100;
free(p);

So try to debug the function. rather than worrying. It will be ok.

If u can Dream... U can do it

Re: Heap Corruption

yaminisridaran6-Aug-07 0:37

yaminisridaran

6-Aug-07 0:37

ok i will try .Thanks

S.Yamini

Re: Heap Corruption

James R. Twine6-Aug-07 1:56

James R. Twine

6-Aug-07 1:56

yaminisridaran wrote:
Image=(unsigned char *)malloc(50000);
Image=Dlg.CaptureImage();
free(Image);

   In the first line, you are allocating memory into the Image pointer.

   In the second line, you are reassigning that pointer to some other value.

   In the third line, you are calling free(...) on the value obtained in the second line, not the value obtained in the first line, so you may be trying to free a invalid pointer.

   Peace!

-=- James
Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles

Re: Heap Corruption

yaminisridaran6-Aug-07 1:57

yaminisridaran

6-Aug-07 1:57

Can u give me any solution for this

S.Yamini

Re: Heap Corruption

James R. Twine6-Aug-07 2:07

James R. Twine

6-Aug-07 2:07

yaminisridaran wrote:
Image=(unsigned char *)malloc(50000);
Image=Dlg.CaptureImage();
free(Image);

Yes, if you skip step #2 and the error goes away, you have found the source of the problem. It seems that you are not passing the allocated memory to CaptureImage(...), and since we do not know what is going on inside of that function, there is little other help that we can provide.

Peace!

Binary File

vipin_nvk5-Aug-07 21:22

vipin_nvk

5-Aug-07 21:22

What is a binary file ? How do u read / write into a binary file.

Thanx

Re: Binary File

Nelek5-Aug-07 22:01

Nelek

5-Aug-07 22:01

Take a look in MSDN about CFile

The modus to read/write is spcified during the creation of the object

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Re: Binary File

cp98765-Aug-07 22:05

cp9876

5-Aug-07 22:05

Text mode treats end line characters differently. Check out the documentation.

Peter
"Until the invention of the computer, the machine gun was the device that enabled humans to make the most mistakes in the smallest amount of time."

Re: Binary File

toxcct5-Aug-07 22:19

toxcct

5-Aug-07 22:19

open it in notepad... if you find it readable, then it's probably a text file.
if it contains "hieroglyphs" or so, then it's a binary file, and you must know the format of how the data have been written in it to read them back

[VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

exe work but dll does not work?

George_George5-Aug-07 20:41

George_George

5-Aug-07 20:41

Hello everyone,

I have written two simple programs (source codes are the same),

1. In an exe, loading a class from another COM component by invoking CoCreateInstance;

2. In a COM DLL, loading a class from another COM component by invoking CoCreateInstance;

1 success but 2 fails. I am running in the same environment (machine) using Visual Studio 2005. Any ideas of this issue?

thanks in advance,
George

WideChar to Variant conversion

Suneet.035-Aug-07 20:29

Suneet.03

5-Aug-07 20:29

Can anyone tell how to convert a widechar string to VARIANT

I have an unsigned char* string , I am converting it to widechar using MultiByteToWideChar.

How to convert it to VARIANT ?

The data is getting lost if i use ColeVariant.

Re: WideChar to Variant conversion

Aamir Butt5-Aug-07 21:09

Aamir Butt

5-Aug-07 21:09

If you paste your code here, that would be more helpful but simply u can do it by setting the vt of variant to VT_BSTR and then create a bstr. Put the string in BSTR by using ::SysAllocString and set that BSTR in the variant.

Something like:
BSTR bstrString = ::SysAllocString(str);
VARIANT var;
var.vt = VT_BSTR;
var.bstrval = bstrString;

Regards,

"Some people believe football is a matter of life and death.
I'm very disappointed with that attitude.
I can assure you it is much, much more important than that. -- Bill Shankly"

Re: WideChar to Variant conversion

Suneet.035-Aug-07 21:41

Suneet.03

5-Aug-07 21:41

I have sumthng like this

VARIANT getData()
{
unsigned char* puc_Data = " SOME TEXT ";

// I am converting the above unsigned char to whar_t* using

MultiByteToWideChar(CP_UTF8,..,puc_Data,len,wchar_t*,len);

// I want to take this wchar string and convert it to VARIANT
// Doing it thru COleVariant

ColeVariant var(wchar string );

// Data is getting lost sumwhere here ...

return var;

Can anyone suggest wat i m doing wrong??

Re: WideChar to Variant conversion

Roger Broomfield6-Aug-07 2:07

Roger Broomfield

6-Aug-07 2:07

Why not just do this and let COleVariant do what it is designed to do?

ColeVariant getData()
{
char* puc_Data = " SOME TEXT ";
ColeVariant var(puc_Data);
return var;
}

OCR example

Maynka5-Aug-07 20:00

Maynka

5-Aug-07 20:00

Hi all,
From where can i found OCR example(converting image into text) in VC++.

Regards

Re: OCR example

Shouvik Das5-Aug-07 21:12

Shouvik Das

5-Aug-07 21:12

Hope this helps you out
http://www.codeproject.com/cpp/OCRwithMODI.asp?df=100&forumid=378728&exp=0&select=2073309[^]

There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
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Regards...
Shouvik

Re: OCR example

ThatsAlok6-Aug-07 1:43

ThatsAlok

6-Aug-07 1:43

Maynka wrote:
From where can i found OCR example(converting image into text) in VC++.

it wholly depend on hardware you are using!..

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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how do switching to ring0

zon_cpp5-Aug-07 19:55

zon_cpp

5-Aug-07 19:55

hi!
how do i switch to ring0 in my program, and i call sidt (asm instruction) for read and change an intrrupt address?

Zo.Naderi-Iran

Re: how do switching to ring0

henky@online-resource.org5-Aug-07 23:27

henky@online-resource.org

5-Aug-07 23:27

Ring0 is in kernel memory area. So, you must create your program
as part of kernel.
(I never create this such program, but as long as i know you must
create modularized program which is registered in OS). D'Oh! | :doh:

Henky Purnawan
henky@online-resource.org

CListCtrl is not display the information in 64-bit windows OS

ksrameshkanth5-Aug-07 18:58

ksrameshkanth

5-Aug-07 18:58

Hi,
I am customizing list control and building with x64 configuration, then testing on 64 bit windows xp professional edition listing of item is missing( Just blank). If any one come across this problem, can help me?

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