C / C++ / MFC

Re: free is needed when app will exit?

4-Jun-09 6:42

Hi guys,
I have a qustion in windows programing like this.
I think free was always needed win16 programing because malloc was implmented by GlobalAlloc and system never free its pointer until GlobalFree called. So it makes a system memory leaks.
But nowadays, in win32 system, malloc is implemented by HeapAlloc and do not need call at program exiting anymore, because system frees its heap safely at process died.
Is this true or not?

Stuart Dootson4-Jun-09 7:09

Stuart Dootson

4-Jun-09 7:09

norish wrote:
But nowadays, in win32 system, malloc is implemented by HeapAlloc and do not need call at program exiting anymore, because system frees its heap safely at process died.

Strictly you are correct - Windows releases a processes resources when the process terminates. However, it's good practise to release resources explicitly, just in case the code gets reused somewhere that it matters. Use smart pointers/resource handles and it becomes easy enough.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: free is needed when app will exit?

norish4-Jun-09 7:49

OnInitDialog() is not called?

4-Jun-09 7:49

Thanks for reply.
I might be correct after all. Smile | :)

However, it's good practise to release resources explicitly

Your point is the very good manner in most case, I know, especially some system handles (like kernel objects) must explicitly release in the code before progaram exits.
So sometimes I use smart pointers for managing such handles.
Wink | ;)

transoft4-Jun-09 6:34

transoft

4-Jun-09 6:34

Hi

I designed a new dialog class as:

class CDialogBase : public CDialog
{
public:
CDialogBase( CWnd* parent, UINT resId );
virtual ~CDialogBase() { }
protected:
void EvHelp(HELPINFO*);

virtual BOOL OnInitDialog();
virtual void OnOK() {};

protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support

public:
afx_msg virtual void CMHelp();

DECLARE_MESSAGE_MAP( );
};

I did following:

CAboutDialog *pAboutDialog = new CAboutDialog( .... ); ---> CAboutDialog is inherited from "CDialogBase "
pAboutDialog->DoModal();

But OnInitDialog() is not called. Where is the problem?

Thanks,

norish4-Jun-09 7:07

4-Jun-09 7:07

pAboutDialog->DoModal();

will immediatelly return?

If then instantiation of CAboutDialog has some error.
I know a case cause this situation.
Check the resource id is exist and reffer exact dialog resource.

If resource id is valid, I'm not sure, maybe some declaration is not matched their prototypes or no appropriate message mapping macro defined...

transoft4-Jun-09 7:38

transoft

4-Jun-09 7:38

Yes, pAboutDialog->DoModal()will immediatelly return.

norish4-Jun-09 8:01

4-Jun-09 8:01

Then problem is decided to initializing an instance.
All constructor of CAboutDialog, CDialogBase, CDialog are initializing correctly?
Are there some members not initilized or have invalid value?
You can check it by debug mode and step into function.

Stuart Dootson4-Jun-09 7:10

Stuart Dootson

4-Jun-09 7:10

transoft wrote:
DECLARE_MESSAGE_MAP( );

Did you do the BEGIN_MESSAGE_MAP()/END_MESSAGE_MAP() thing correctly? CDialogBase needs that...

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

transoft4-Jun-09 7:39

transoft

4-Jun-09 7:39

Yes, I did as following:

BEGIN_MESSAGE_MAP( CDialogBase, CDialog )
ON_COMMAND(IDHELP, CMHelp)
ON_WM_HELPINFO()
END_MESSAGE_MAP()

ChosenOne5-Jun-09 9:44

ChosenOne

5-Jun-09 9:44

you are missing the ON_WM_INITDIALOG in the message map.

David Crow4-Jun-09 10:23

David Crow

4-Jun-09 10:23

transoft wrote:
CAboutDialog *pAboutDialog = new CAboutDialog( .... ); ---> CAboutDialog is inherited from "CDialogBase "
pAboutDialog->DoModal();

Just out of curiosity, why not use:

CAboutDialog pAboutDialog;
pAboutDialog.DoModal();

Do you have any controls on CAboutDialog with associated member variables? Is DoDataExchange() correct? Have you tried adding the DS_NOFAILCREATE style?

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How to show a dialog box when some background processing started

Cristian Amarie4-Jun-09 18:31

Cristian Amarie

4-Jun-09 18:31

Most probably it fails during dialog construction (CreateDialogIndirect).
Invalid or changed IDD (rebuild needed?), ActiveX added in dialog but not (correctly) installed etc.
Or perhaps you are mapping in the same .exe multiple dlls and there is a clash between resource IDs?

BTW, why new CAboutDialog and not
[code]
CAboutDialog dlg;
dlg.DoModal();
[/code]

Nuclear launch detected

pandit844-Jun-09 5:55

pandit84

4-Jun-09 5:55

How to show a Modal Dialog box while i am doing some manipulation to my data before showing it to a grid.
Do i have to start any thread for it .??

Or should I set any event for it..?

Re: How to show a dialog box when some background processing started

Code-o-mat4-Jun-09 6:02

Code-o-mat

4-Jun-09 6:02

I'd say your options are threads or idle-time processing depending on your needs and goals.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Create Process in background

krishnakumartm4-Jun-09 5:25

4-Jun-09 5:25

Hi,
I need to run a process without showing to user, in background,
The application is not a MFC it is normal command window application.
I tried the way like settinf the STARTUPINFO like SW_HIDE. But this is not working.

Can someone help me.

Thanks,

----------------------------
KRISHNA KUMAR T M

Uwe Keim4-Jun-09 5:29

Uwe Keim

4-Jun-09 5:29

As far as I know, a Console application always shows the console.

Try creating a windows application and hide the main window.

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krishnakumartm4-Jun-09 5:42

4-Jun-09 5:42

Why it is like that, is there any other way to hide the console.

----------------------------
KRISHNA KUMAR T M

krishnakumartm4-Jun-09 5:57

4-Jun-09 5:57

Hey i got it we can hide the cosole application also.
we have to fill the STARTINFO structure correctly
like

STARTUPINFO si;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);

//set the flags to tell application to use the startup info
si.dwFlags = STARTF_USESHOWWINDOW;
//set the window hide options.
si.wShowWindow = SW_HIDE;

Refere the link Running console applications silently

----------------------------
KRISHNA KUMAR T M

norish4-Jun-09 6:02

4-Jun-09 6:02

This code can hide console window on my system (xp sp3).

STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
si.dwFlags  = STARTF_USESHOWWINDOW;
si.wShowWindow  = SW_HIDE;
if (CreateProcess(NULL, _T("cmd.exe"), NULL, NULL, FALSE, 0,
        NULL, NULL, &si, &pi)) {
    WaitForSingleObject(pi.hProcess, INFINITE);
    CloseHandle(pi.hThread);
    CloseHandle(pi.hProcess);
}

krishnakumartm4-Jun-09 6:13