Re: strcpy working even after deleting the pointer - C / C++ / MFC Discussion Boards

Cristian Amarie8-Jan-07 1:38

8-Jan-07 1:38

These are WinUser resources. MFC resource IDs are located in afxres.h (which in turn includes also winres.h). You may want to check also the .rc files located in Platform SDK in ../mfc/src.

Nuclear launch detected

Re: Reserved resource IDS of MFC

Mark Salsbery8-Jan-07 6:06

Mark Salsbery

8-Jan-07 6:06

This is an old article but it hasn't changed much, if any (cross check with a new MFC app to
be sure Smile | :)

)

MFC ID Naming and Numbering Conventions[^]

To prevent clashes with IDs auto-generated by the resource editor in VS, this article
(particularly the _APS_NEXT_xxx related stuff) may help:

Using Multiple Resource Files and Header Files with Visual C++[^]

Item icon in Add/Remove progarms dialog

LiYS7-Jan-07 20:43

LiYS

7-Jan-07 20:43

Hi all:

I wonder how the icon for the items in A/R program dialog is set?

Re: Item icon in Add/Remove progarms dialog

Monty²7-Jan-07 20:59

Monty²

7-Jan-07 20:59

Set the following reg value
Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*MyProduct*\
ValueName: DisplayIcon
Value: C:\MyProg\MyProg.exe,0 (0 being the icon no in the resource)

If you think you can than you can, if you think you can't you are right.

strcpy working even after deleting the pointer

pyarigopal7-Jan-07 20:42

pyarigopal

7-Jan-07 20:42

This is the code i am trying in visual studio 2005.

char *str = new char[100];
delete [] str;
strcpy ( str, "good_moring" );
cout<

Re: strcpy working even after deleting the pointer

Monty²7-Jan-07 21:08

Monty²

7-Jan-07 21:08

The results of operation on a deleted pointer are *undefined* (thats why you should set the pointer to null right after deleting it)

If you think you can than you can, if you think you can't you are right.

Re: strcpy working even after deleting the pointer [modified]

Michael Dunn7-Jan-07 21:10

Michael Dunn

7-Jan-07 21:10

Because the page in the process's virtual address space that str pointed to is not released right away. In fact it would probably get re-used if you immediately called new again.

In short: it's luck and it's a bug to access memory after using free/delete on it.

--Mike--
Visual C++ MVP Cool | :cool:

LINKS~! Ericahist | PimpFish | CP SearchBar v3.0 | C++ Forum FAQ

Re: strcpy working even after deleting the pointer

Waldermort7-Jan-07 21:14

Waldermort

7-Jan-07 21:14

The operator new allocates the space and assigns an address to the variable. The operator delete only marks that memory as re-usable, it does not change the assigned pointer. Your code will not throw any errors because all strcpy will do is check theat the address points to memory, it will not check if it is usable or not.

If in your test code you allocated and used more memory after deleteing str and before strcpy, you may find that the same memory is being used. The golden rule is, set the address to NULL directly after calling delete.

Re: strcpy working even after deleting the pointer

pyarigopal8-Jan-07 18:21

pyarigopal

8-Jan-07 18:21

thanks...
so better to follow the goldern rule.

Re: strcpy working even after deleting the pointer

CPallini7-Jan-07 21:25

CPallini

7-Jan-07 21:25

pyarigopal wrote:
still its printing good_morning with out throwing any exception.
why this is happening ?

Perhaps delete is only marking the memory chunk as free and strcpy doesn't matter about, as stated by MSDN:

The strcpy function copies strSource, including the terminating null character, to the location specified by strDestination. No overflow checking is performed when strings are copied or appended

try this:

char *p = new char[100];
delete [] p;
char *q = new char[100];
strcpy(p,"Hello world\n");
strcpy(q,"Good news...\n");
printf("%s", p);
printf("%s", q);

if you're a lucky boy, like me, you will see the following output:

Good news...
Good news...

hence you're loosing the freed memory.

As already stated by other posters, NEVER DO SUCH NASTY THINGS.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: strcpy working even after deleting the pointer

prasad_som7-Jan-07 21:29

prasad_som

7-Jan-07 21:29

to add to all replies, use strcpy_s and take benefit of Security Enhancements in the CRT.

Prasad
Notifier using ATL | Operator new[],delete[][^]

How can i use Image magick in MFC?

$uresh $hanmugam7-Jan-07 20:17

$uresh $hanmugam

7-Jan-07 20:17

Hi all,

I have creating dialog based window in vc++(MFC) and installed image magic(dynamic dll of binary version).

I need to know about InitializeMagic(char *) function. Is Magic must be initialize?... and when i read one image using read(std::string) function.....

#include Magick++.h<br />
#include iostream<br />
using namespace std;<br />
using namespace Magick; <br />
<br />
{<br />
 Image img;<br />
img.read("c:\\logo.jpg");<br />
}

Error will be thrown like......

Unhandled exception at 0x000c256.. in sample.exe:0xC000075:
Access voilation writing location 0xcde....

Anybody know about this problem let me know...

Thankx in advance...

Re: How can i use Image magick in MFC?

Hamid_RT7-Jan-07 20:37

Hamid_RT

7-Jan-07 20:37

I think you asked like this question you can also use of GDI+ or CImage class for read graphic files.(jpg,gif,png,..)

WhiteSky

Re: How can i use Image magick in MFC?

$uresh $hanmugam7-Jan-07 21:04

$uresh $hanmugam

7-Jan-07 21:04

Hi WhiteSky,

Just now i had read your previous reply, Sorry.......

I dont want that just read one image and save to another file. My target is convert multipage PDF file into image file with good resolution for OCR process. Can i use GDI+ or CImage for this conversion...

Re: How can i use Image magick in MFC?

Hamid_RT7-Jan-07 21:37

Hamid_RT

7-Jan-07 21:37

I think no but see here[^] if its helpfuls

WhiteSky

Re: How can i use Image magick in MFC?

$uresh $hanmugam7-Jan-07 21:51

$uresh $hanmugam

7-Jan-07 21:51

But there is only Image to PDF converter

DLL Injection vs Code Injection

SelvaKr7-Jan-07 20:06

SelvaKr

7-Jan-07 20:06

Hi,

I need to write an injection module for my application.

Which one would be the best. Code Injection or DLL Injection. What are the advantages over the other...

Heard that, DLL injection can be used in all the windows OS. but code injection can be applied only on NT Operating sys.

Is there any other advantages or problems in using either of them..

Please advice me.

Thanks.

~ Selva

Re: DLL Injection vs Code Injection

Stephen Hewitt7-Jan-07 20:18

Stephen Hewitt

7-Jan-07 20:18

To my mind "DLL injection" is a form of "Code Injection". If the code in question is complex DLL injection is the easiest way to get your code into another process. If you attempt to inject raw code you lose actions the loader performs which we all take for granted such as automatic code relocation; not to mention the fact that compilers build DLL's not "naked" code.

Steve

Re: DLL Injection vs Code Injection

SelvaKr7-Jan-07 20:25

SelvaKr

7-Jan-07 20:25

Thanks Steve.

I will just go with DLL Injection in that case.

~ Selva

Title

Try7-Jan-07 18:56

Try

7-Jan-07 18:56

Hello everyone,

I have designed a SDI application. I have assigned the title for the document using SetTitle() function in AbcDoc.cpp file.

I want to assign the title at runtime (i.e i have provided text box in a dialog). How should i do this?

Please help me.

Thanks in Advance.

Re: Title

prasad_som7-Jan-07 19:17

prasad_som

7-Jan-07 19:17

You can follow this root,

((CFrameWnd*)AfxGetMainWnd())->GetActiveDocument()->SetTitle("New");

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Title

Try7-Jan-07 19:24

Try

7-Jan-07 19:24

Thank You very much. It works..

DLL and Program Compile

uusheikh7-Jan-07 18:54

uusheikh

7-Jan-07 18:54

Assume I have a DLL with a function void BFunction(). I link this Dll to a program (test.exe) using its .lib and .h.

If, in the future, i add a new function to the Dll - void AFunction(), will i have to recompile test.exe even if test.exe does not (and will not) use the AFunction() ?

Since the Dll has changed, are the pointers to the functions in the dll are still the same? Or by adding a new function will cause existing programs to crash, and these existing programs must be recompiled as well?

Please help,
Thanks.

Re: DLL and Program Compile

Rajesh R Subramanian7-Jan-07 19:10

Rajesh R Subramanian

7-Jan-07 19:10

You do not need to recompile test.exe until your new dll exports the function that is being called by test.exe

test.exe is only concerned about the function that it calls. No matter if you add or remove any other functions in the dll.

Nobody can give you wiser advice than yourself. - Cicero
ப்ரம்மா

Re: DLL and Program Compile

uusheikh7-Jan-07 19:22

uusheikh

7-Jan-07 19:22

Does it mean, that i can keep on adding new functions to a dll (and export these functions) or modify the behavior of existing exported functions, and i do not have to recompile existing programs which are already linked to it?

Example
DLL ver1.0 - Functions : void BFunction(), void CFunction();

test.exe (calling BFunction()) is linked using .lib, .h during compile time to this DLL.

DLL ver 2.0 - Added function void AFunction(), and modified internal behavior of BFunction().

test.exe will still work fine? Since the function prototype of BFunction is still the same, test.exe should work fine right?

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