Re: MFC CreateEx function crashes program - C / C++ / MFC Discussion Boards

ChrisBuckley2-Oct-09 3:23

2-Oct-09 3:23

I have been updating an MFC application that has the following line of code in it to create Edit Boxes (Note tmp is a CString object):

CreateEx(WS_EX_CLIENTEDGE, _T("EDIT"), _T(tmp), WS_CHILD | WS_TABSTOP | WS_VISIBLE, *pMyRects[0], pParent, resourceId);

Up until recently, this code has worked fine. On my latest build, only the Debug build works. The Release build crashes. I traced the crash to this particular line of code. The CreateEx function actually never returns. I can't debug it, since as I said the Debug configuration doesn't crash.

What's weird is when I replaced the _T(tmp) parameter with _T("") so the line looks like below, the Release build doesn't crash.

CreateEx(WS_EX_CLIENTEDGE, _T("EDIT"), _T(""), WS_CHILD | WS_TABSTOP | WS_VISIBLE, *pMyRects[0], pParent, resourceId);

I've googled this issue and can't find anything like it anywhere. Does anyone know if there is some issue passing a CString to the CreateEx function or if there's a problem because the CString was created locally in the function?

Another strange quirk is that I ran the Release executable on a machine with Vista (rather than XP which is what I am developing on) and the code doesn't crash.

Re: MFC CreateEx function crashes program

Cedric Moonen2-Oct-09 3:48

Cedric Moonen

2-Oct-09 3:48

Why are you using the _T() macro on a CString ? Try removing it and see if this fixes your problem.

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

Re: MFC CreateEx function crashes program

ChrisBuckley2-Oct-09 4:13

ChrisBuckley

2-Oct-09 4:13

Sorry, I didn't specify that before, originally I wasn't using the _T macro, I was just passing the CString by itself. That crashed the program too.

Re: MFC CreateEx function crashes program

transoft2-Oct-09 6:13

transoft

2-Oct-09 6:13

Did you try "tmp.GetBuffer()"?

Re: MFC CreateEx function crashes program

ChrisBuckley2-Oct-09 7:14

ChrisBuckley

2-Oct-09 7:14

Hadn't tried GetBuffer(), but tested it out and that crashed it too.
Strangly, setting up a local char * and passing it in works just fine too, it's just passing anything associated with the CString object.

Re: MFC CreateEx function crashes program

transoft2-Oct-09 7:23

transoft

2-Oct-09 7:23

How about following?

TCHAR tempString[...]; 

strcpy(tempString, tmp.Getbuffer());

CreateEx(, , tempString, ....

Re: MFC CreateEx function crashes program

ChrisBuckley2-Oct-09 7:47

ChrisBuckley

2-Oct-09 7:47

transoft wrote:
TCHAR tempString[...]; strcpy(tempString, tmp.Getbuffer());CreateEx(, , tempString, ....

Nope, doesn't work either. What I can't understand is why this code existed in previous builds and now causes a problem, why it works in Vista, and why the Debug Configuration in XP also works. The whole executable is around 5000 lines of code plus a driver to a hardware card so the project isn't huge, but not tiny either. So I suppose it could be some strange interaction with memory somewhere or something with the stack.

Re: MFC CreateEx function crashes program

transoft2-Oct-09 8:54

transoft

2-Oct-09 8:54

There must be some reason.

Are you sure that "CreateEx" crashed your software? Like "strcpy" will also crash program because of temp string has not enough buffer.

Could you post your code here?

Re: MFC CreateEx function crashes program

ChrisBuckley5-Oct-09 4:24

ChrisBuckley

5-Oct-09 4:24

transoft wrote:
e you sure that "CreateEx" crashed your software? Like "strcpy" will also crash program because of temp string has not enough buffer.

Could you post your code here?

No, I'm not positive that CreateEx is THE cause, all I know is that the
code crashes before the function ever returns. I had narrowed this down by putting Message Boxes throughout the code and the last one that successfully displayed was immediately before the CreateEx() call.
Here's the code that crashed:

void DialogEditBoxObject_Class::init(CWnd *pParent, CString ctrlText, UINT resourceId)
{
CString tmp;
tmp.Format("%d", nLimit); //nLimit is a class member

//pMyRects are allocated in the constructor and do exist here
CreateEx(WS_EX_CLIENTEDGE, _T("EDIT"), tmp, WS_CHILD | WS_TABSTOP | WS_VISIBLE, *pMyRects[0], pParent, resourceId);

CRect clientRect;
GetClientRect(clientRect);
pMyFont->CreateFont(clientRect.Height(),0,0,0,FONT_HEIGHT(700),0,0,0,
ANSI_CHARSET,OUT_DEFAULT_PRECIS,
CLIP_DEFAULT_PRECIS,
DEFAULT_QUALITY,
DEFAULT_PITCH|FF_DONTCARE,
"arial");
SetFont(pMyFont); //pMyFont was allocated in the constructor

}

Re: MFC CreateEx function crashes program

Tim Craig3-Oct-09 21:58

Tim Craig

3-Oct-09 21:58

Often when the debug version works and the release crashes and you're dealing with pointers, you might have an uninitialized pointer. The debug heap zeros data blocks before it returns them and the release version doesn't. The pointer value itself is nonNULL but contains garbage so when something dereferences it, the program crashes. If the function accepts NULL as a valid pointer, it obviously checks and doesn't try to dereference the pointer. Since it worked before, you may just have gotten lucky and the garbage in the pointer pointed to something that could be interpreted as a valid string.

You measure democracy by the freedom it gives its dissidents, not the freedom it gives its assimilated conformists.

Re: MFC CreateEx function crashes program

ChrisBuckley5-Oct-09 4:59

ChrisBuckley

5-Oct-09 4:59

Tim Craig wrote:
Often when the debug version works and the release crashes and you're dealing with pointers, you might have an uninitialized pointer. The debug heap zeros data blocks before it returns them and the release version doesn't. The pointer value itself is nonNULL but contains garbage so when something dereferences it, the program crashes. If the function accepts NULL as a valid pointer, it obviously checks and doesn't try to dereference the pointer. Since it worked before, you may just have gotten lucky and the garbage in the pointer pointed to something that could be interpreted as a valid string.

Thanks, that's useful to know. I was imagining that it could be a memory problem somewhere. The code I inherited when I took this project over was awful; even the debug version was letting me know about numerous memory leaks. I wrapped most of the code in classes and cleaned up new/delete calls all over but it is possible there is a more subtle problem going on that the debugger isn't letting me know about.

Debug Error - Calling a class member function declared in another file

AntoineBab2-Oct-09 3:14

AntoineBab

2-Oct-09 3:14

I'm a french new MFC programmer, and at run-time (compiling is OK), I got a message from MSVC++. This message is a Debug Error(Value of ESP was not properly saved...Problem of convention function calling). It's seems I located the call function which generate this exception. Following a piece of my source code. I think it's a function declaration problem. Thank's if someone could help me.

// repository.h
class CRepository
{
{
	struct Server {
		struct AutomationModules { 
			int  nDataValid;
			char szFilename[20];
			char szDrawrow1[50];
			char szDrawrow2[50];
			char szDateModifier[10];
		};
		char szServerName[20];						// Individual Server name
		// array files of XXX element of type AutomationModules
		AutomationModules files [MAX_FILES];
		int nValid;									// validity
	};
//Défintion des éléments accesiblent à l'exterieur de la classe
public:
	CString RepositoryName;							// Repository name
	bool bModify;									// Repository state

	//// array server of XXX element of type Server
	Server server[MAX_SERVERS];

	CRepository() {} 
	virtual ~CRepository() {}


.....
public:
void InverseServer(CRepository::Server *Svr1,CRepository::Server *Svr2);
...
};

// heap object
CRepository *pRepository = new CRepository;


// calling from another file 
// xxx.cpp
...
extern CRepository *pRepository
...
pCrepository->InverseServer(&server[j],&server[j+1]);
...

Re: Debug Error - Calling a class member function declared in another file

David Crow2-Oct-09 8:56

David Crow

2-Oct-09 8:56

AntoineBab wrote:
...I got a message from MSVC++. This message is a Debug Error(Value of ESP was not properly saved...Problem of convention function calling).

Which statement is generating the error?

AntoineBab wrote:
pCrepository->InverseServer(&server[j],&server[j+1]);

What is the value of pCrepository at this point?

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

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Background Colour of TabControl

Deepak.Prahlad2-Oct-09 3:00

Deepak.Prahlad

2-Oct-09 3:00

Hi
How can I change the color of a Tab Control? I manged to change the color of a static text and dialog. I need to change the color of the Button control and Tab control from the default gray to a color matching my dialog. How to do this? Please help

Thanks in advance
Deepak

Re: Background Colour of TabControl

Deepak.Prahlad6-Nov-09 21:08

Deepak.Prahlad

6-Nov-09 21:08

I got a solution for Tab Controls. Atleast what I intended to do.

It is here CXTabCtrl: an easier tab control for dialogs and forms[^]
and
Ownerdraw Tab Controls - Borders and All[^]

I managed to club the functionality from these two and achieved my objective.

Thanks to http://www.codeproject.com/Members/xicoloko[^]
and
http://www.codeproject.com/Members/dan-g[^]

Deepak

how to pass arguments to createproces() function

WindowsVsLinux2-Oct-09 1:26

WindowsVsLinux

2-Oct-09 1:26

hi,
i have a C++ program which can open cmd using createprocess() function but i want to give command to cmd.means when i run my program it will open cmd and if i want to show the directory i ahve to write in cmd dir but i want that i write dir in my program and it will automatically execute in cmd.can i do this?

Re: how to pass arguments to createproces() function

CPallini2-Oct-09 1:57

CPallini

2-Oct-09 1:57

Do you have troubles adding "cmd " to the actual command typed in your application?
You may also use the system CTR function, for instance

void main()
{
  system("dir");
}

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.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: how to pass arguments to createproces() function

WindowsVsLinux2-Oct-09 2:34

WindowsVsLinux

2-Oct-09 2:34

no no actually i use there scanf function and if i use system() commmand and type command cd c:\ then it will not goes to c: drive.I simply want to write a program which can give command to cmd and show me the output in my C++ running window.means whatever cmd shows it will be shown on my screen

Re: how to pass arguments to createproces() function

Michael Schubert2-Oct-09 2:39

Michael Schubert

2-Oct-09 2:39

Are you talking about console input/output redirection?

Re: how to pass arguments to createproces() function

WindowsVsLinux2-Oct-09 2:44

WindowsVsLinux

2-Oct-09 2:44

ya ya Michael

Re: how to pass arguments to createproces() function

David Crow2-Oct-09 2:50