C / C++ / MFC

29-Apr-09 1:13

hi every one

I create a static library with visual c++ 6.0 App wizard.
I create a new generic class and declared my variables in its header file.
Then I initialized my variables in class constructor.

I want to use it in a new dialog based project, so I add related header file and write my library name in linker tab at project setting.

I create one object of this class in my function, But at the end of function when application exits from function occurs an exception.
I can't handle this exception.

Note : when I comment initialized this exception don’t happen.
Please help me

////////////////////////////////////////////////////////////////
// static library class (Test.h)
///////////////////////////////////////////////////////////////

class CTest  
{
public:
		
	CTest();
	virtual ~CTest();
	
	int		 m_i1;//or INT   
	int		 m_i2;   
	
        bool		 m_b1;//or BOOL
	bool		 m_b2;
	
	unsigned int	 m_ui1;//or DWORD32
	unsigned int	 m_ui2;
	
	unsigned short   m_us1;//or USHORT
	unsigned short   m_us2;
	
	BYTE		 m_bte1;//#include <windef.h> in stdafx.h for BYTE data type
	BYTE		 m_bte2;
	
	CString	 m_str1;//#include <afx.h> in stdafx.h for CString data type
	CString	 m_str2;	
};</afx.h></windef.h>

// (Test.cpp)
///////////////////////////////////////////////////////////////
#include "stdafx.h"
#include "Test.h"

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CTest::CTest()
{
	
	m_i1=0;
	m_i2=0;  
		
	m_b1=true;
	m_b2=true;
		
	m_ui1=0;
	m_ui2=0;
		
	m_us1=1;
	m_us2=1;
		
	m_bte1=0;
	m_bte2=0;
		
	m_str1="";
	m_str2="";
		
}

CTest::~CTest()
{


}

////////////////////////////////////////////////////////////////
// My dialog base application
///////////////////////////////////////////////////////////////

void CUseTestLibDlg::OnBinitlib() 
{
	CTest  *pcTest=new CTest();

        delete pcTest;
	pcTest=NULL;
	
	
}// Unhandled exception in UseTestLib.exe: 0xC0000005: Access Violation.

void CUseTestLibDlg::OnBinitlib2() 
{
	CTest  pcTest;
	
}// Unhandled exception in UseTestLib.exe: 0xC0000005: Access Violation.

modified on Wednesday, April 29, 2009 6:26 AM

CPallini29-Apr-09 1:20

CPallini

29-Apr-09 1:20

samira forooghi wrote:
pcTest=NULL;
delete pcTest;

I would invert the order of the statements... Roll eyes | :rolleyes:

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]

samira forooghi29-Apr-09 1:30

29-Apr-09 1:30

thanks for u
i correct it ,but its not my problem.

Stephen Hewitt29-Apr-09 1:30

Stephen Hewitt

29-Apr-09 1:30

Looks like good advice...

Steve

Stuart Dootson29-Apr-09 1:36

29-Apr-09 1:36

Shouldn't cause an accvio, though - you can delete NULL in C++.

Maximilien29-Apr-09 1:43

Maximilien

29-Apr-09 1:43

but will result in a memory leak.

This signature was proudly tested on animals.

Stuart Dootson29-Apr-09 1:46

29-Apr-09 1:46

I didn't say it wouldn't - I was just saying that fixing it wouldn't solve the OP's problem.

samira forooghi29-Apr-09 2:01

29-Apr-09 2:01

Thanks a lot

Rajesh R Subramanian29-Apr-09 2:21

Rajesh R Subramanian

29-Apr-09 2:21

Yes, but Carlo just indicated one of flaws in the OP's code. I agree that it wouldn't solve 'the problem' of the OP, but it might (hopefully) prevent the OP from shooting his own face sometime in the future. Smile | :)

It is a crappy thing, but it's life -^ Carlo Pallini

samira forooghi29-Apr-09 1:45

29-Apr-09 1:45

i havent any problem with new delete , occur exception even this case

void CUseTestLibDlg::OnBinitlib2() 
{
	CTest  pcTest;	
}// Unhandled exception in UseTestLib.exe: 0xC0000005: Access Violation.

Stuart Dootson29-Apr-09 1:45

C++ / JNI object instance problems

29-Apr-09 1:45

The problem's obviously in CTest's destructor. The only significant activity in CTest's destructor will be calls to m_str1's and m_str2's destructors. Therefore, the access violation is happening somewhere in there.

I suspect there's something not quite right with your project settings - check that the library and main app are using hte same MFC and C run-time library settings.

megaadam29-Apr-09 0:53

megaadam

29-Apr-09 0:53

I have just started at a new job. Here we are new to using JNI ( for bridging C++ / Java ). I am new to JNI so please forgive my noobness Smile | :)

In our (win32) Java app we are loading a C++ DLL. On the Java side we have several instances of "SomeJClass" each of these instances needs access to corresponding instance of "SomeCClass" on the DLL side. The DLL exposes entry-points such as GlobalDoSomethingInC(). Here I must call the instance method of Doer::DoSomethingInC(). So I need a smooth way to map the respective this-pointers. I also need to do the same mapping when a DLL thread discovers something interesting that it needs to notify the corresponding Java-instance of.

I can think of several solutions, but I do not like them too much. My question is, is there a better way than this ?

1 Java calls C:GetNewInstance(). This returns an int that is actually a pointer to the new C instance. Java stores it in m_myCInstance. Then Java calls GlobalDoSomethingInC(), and 1a

// DLL global<br />
void GlobalDoSomethingInC()<br />
{<br />
    // retrive this pointer<br />
    //calling back to Java:  <br />
    jobj tmpJ = NewGlobalRef( env, obj );<br />
    Doer* myDoer = <reinterpret_cast>( Doer )tmpJ->GetMyCInstance();<br />
    myDoer->DoSomething();<br />
    DeleteGlobalRef( env, tmpJ );<br />
    // Arrrrgh<br />
}<br />
</reinterpret_cast>

1b or:

    // for **every call** that Java adds a parameter, <br />
    //which is the stored int:m_myCInstance, and<br />
    Doer* myDoer = <reinterpret_cast>( Doer )instanceParam->DoSomethingInC();<br />
    // Can we do better that this?<br />
<br />
</reinterpret_cast>

2 For calling from C to Java, things look, maybe, better

In the constructor C calls back into Java and stores
the Java instance reference

in a member variable. m_myJInstance.<br />
In all subsequent calls m_myJInstance can be used to call back Java.<br />
In the destructor we need to call DeleteGlobalRef( env, m_myJInstance );<br />

Not too bad I suppose. But it really safe to store the jobject reference. I mean: What happens when the GC moves the object around?

3 Our present solution does "work". But it belongs on rather on http://www.codinghorror.com/blog/ Smile | :)

Another question, for JNI experts only. How much juice does it cost to do this sequence:

<br />
    jobj tmpJ = NewGlobalRef( env, obj );<br />
    tmpJ->GetMyCInstance();<br />
    DeleteGlobalRef( env, tmpJ );

Thanks
Adam

........................
Life is too shor

creating menus dynamically

Farhat Aisha29-Apr-09 0:33

Farhat Aisha

29-Apr-09 0:33

I have a MDI application which has several document types. And I am adding sub-menus dynamically for some of the document types. The follwoing is the code snippet

class CMyMenu: public CMenu
{
int data1;
...
public:
virtual ~CMyMenu(){};
};

Then in the mainframe I declare a function AddNewMenu
CMainFrame::AddMenu(HMENU hMenu)
{

CMyMenu *pMenu = (CSMenu*)CSMenu::FromHandle( toolbarMenu );

CMyMenu* popup1 =

new CSMenu(), *popup2 = new CSMenu();

//create the two pop-up menus
createPopup1(&popup1);
createPopup2(&popup2);

pMenu ->AppendMenu( MF_POPUP, (UINT)popup1->GetSafeHmenu(), "Popup1" );
pMenu ->AppendMenu( MF_POPUP, (UINT)popup2->GetSafeHmenu(), "Popup2" );

...
}

My question is if I call ::DestroyMenu(hMenu) later on, it will delete all the submenus but will it delete the associated "CMyMenu" objects too or do I have to save both popup1 and popup2 to delete the objects my self

Please reply
Thanks

Re: creating menus dynamically

led mike29-Apr-09 5:21

led mike

29-Apr-09 5:21

Farhat Aisha wrote:
My question is if I call ::DestroyMenu(hMenu) later on, it will delete all the submenus but will it delete the associated "CMyMenu" objects too or do I have to save both popup1 and popup2 to delete the objects my self

Well I guess you can either choose to believe the documentation, or not. If you don't believe it then you can perform some tests to see if it leaks.

DestroyMenu[^]

Remarks

Before closing, an application must use the DestroyMenu function to destroy a menu not assigned to a window. A menu that is assigned to a window is automatically destroyed when the application closes.

DestroyMenu is recursive, that is, it will destroy the menu and all its submenus.

Clear X-Box from the system menu

Shashi.Shinde29-Apr-09 0:24

Shashi.Shinde

29-Apr-09 0:24

Hi,
Actually i need to vanish the 'X'-box from the system menu & keep only Minimize-Box in the menu bar.
I'hv used a code stuff under OnInitDialog()---
CMenu* cmenu = this->GetSystemMenu(FALSE);
cmenu->ModifyMenu(SC_CLOSE,MF_BYCOMMAND | MF_GRAYED);

OR

CMenu* cmenu = GetSystemMenu(FALSE);
cmenu ->RemoveMenu(SC_CLOSE,MF_BYCOMMAND );
cmenu ->RemoveMenu(0,MF_BYPOSITION);

==>In both cases ,it only disabling the X-box not vanishing from the menu bar.

So is there any way to totally clear this X-box.
If then plz repay as soon as possible.

Thanks in advance Smile | :)

Re: Clear X-Box from the system menu

Stuart Dootson29-Apr-09 1:22