Is there any memory leak in this code? - C / C++ / MFC Discussion Boards

Re: diamond problem and virtual inheritance

SandipG 22-Sep-08 21:07

22-Sep-08 21:07

George_George wrote:
But when overriding only in one class, there is no compile error regarding the ambiguity issue, why??

In that case i think preference is given to overridden method.
and you can always use scope resolution operator to execute desired method Smile | :)

Regards,
Sandip.

Re: diamond problem and virtual inheritance

George_George22-Sep-08 21:26

George_George

22-Sep-08 21:26

Thanks Sandip,

"In that case i think preference is given to overridden method." -- you mean when calling D.Display, there are two choices,

1. D::B::Display;
2. D::C::A::Display.

But since (1) is "more" overridden than (2), (1) is preferred, but if we derive Display in both B and C, D will have no choice and there will be ambiguity compile error?

regards,
George

Re: diamond problem and virtual inheritance

SandipG 22-Sep-08 21:30

SandipG

22-Sep-08 21:30

George_George wrote:
"In that case i think preference is given to overridden method." -- you mean when calling D.Display, there are two choices,

1. D::B::Display;
2. D::C::A::Display.

But since (1) is "more" overridden than (2), (1) is preferred,

Yes from the behavior it seems like that.
Even i did not come across any documents that states above behavior.

Regards,
Sandip.

Re: diamond problem and virtual inheritance

George_George22-Sep-08 21:34

George_George

22-Sep-08 21:34

Thanks Sandip,

Here is what I learned from you -- virtual inheritance solves both member method and member data issue -- so we can say virtual inheritance solves all diamond problem issues (both ambiguity member method and data member). Could you review and confirm my understanding now is correct please? Smile | :)

regards,
George

Re: diamond problem and virtual inheritance

SandipG 22-Sep-08 21:37

SandipG

22-Sep-08 21:37

Yes unless there is no overriding of methods from the common ancestor as i said earlier.

Regards,
Sandip.

Re: diamond problem and virtual inheritance

George_George22-Sep-08 21:39

George_George

22-Sep-08 21:39

I agree, thanks Sandip!

regards,
George

Re: diamond problem and virtual inheritance

laksh220422-Sep-08 23:03

laksh2204

22-Sep-08 23:03

I have some queries here..

1. By making the inheritance virtual how the ambiguity is actually resolved?
I mean, what this virtual inheritance does internally? Does it create another vptr of another vtable?
if it is so how does the new vtable looks like??

2. And as the diamond problem says that there is an ambiguity that whether D will have path
A->B->D
or
A->C->D

A
/ \
B C
\ /
D

So after removing ambiguity which path is taken?

Is there any memory leak in this code?

SRKSHOME22-Sep-08 19:33

SRKSHOME

22-Sep-08 19:33

Hi,
Is there any memory leak in the following code? I cannot see any one. But bound checker telling there is a leak? Please advice me. Thanks in advance.

class test<br />
{<br />
	char* m_name;<br />
public:<br />
	test():m_name(NULL)<br />
	{}<br />
	void Set(const char* name)<br />
	{<br />
		<br />
		if(name!=NULL && strlen(name))<br />
		{<br />
			m_name = new char[strlen(name)+1];<br />
			strcpy(m_name,name);<br />
		}<br />
		else<br />
			delete [] m_name;<br />
	}<br />
	~test()<br />
	{<br />
		Set(NULL);<br />
	}<br />
	void display()<br />
	{<br />
		cout<<m_name<<endl;<br />
	}<br />
};<br />
int main(int argc, char* argv[])<br />
{       test tst;<br />
	tst.Set("123456");<br />
	tst.display();	<br />
	return 0;<br />
}<br />

Re: Is there any memory leak in this code?

User 21559722-Sep-08 19:53

User 215597

22-Sep-08 19:53

SRKSHOME wrote:
void Set(const char* name)
{

if(name!=NULL && strlen(name))
{
m_name = new char[strlen(name)+1];
strcpy(m_name,name);
}
else
delete [] m_name;
}

Assuming name is valid
On first call to Set method, m_name is NULL and you allocate memory to it.
On second call to Set method, m_name had valid allocated memory from first call. But prior to allocating new memory, the previous allocated memory is not deallocated

modified 21-Apr-21 21:01pm.

Re: Is there any memory leak in this code?

SRKSHOME22-Sep-08 20:49

SRKSHOME

22-Sep-08 20:49

Thanks for your reply. But if you look at the main function I have called set("123456"). I have never called set(..) for second time. Second time this functin is called from destructor and NULL is passed to Set(). Hence I cannot see memory leak here. Please correct me if I am wrong.

Re: Is there any memory leak in this code?

User 21559722-Sep-08 21:46

User 215597

22-Sep-08 21:46

I see the above as obvious memory leak in code. Also Sarath (in the reply below) pointed to the same problem. Try fixing the problem and then see if there is still memory leak.

You may also want to re-think about how m_name is deallocated when object lifetime ends.

modified 21-Apr-21 21:01pm.

Re: Is there any memory leak in this code?

Sarath C22-Sep-08 20:46

Sarath C

22-Sep-08 20:46

The program will be having memory leak, if you call set twice. You can rewrite the code better.

class test
{
	char* m_name;
public:
	test():m_name(NULL)
	{}
	void Set(const char* name)
	{
		// Leave the data untouched on invalid input
		if( name == NULL || 0 == strlen(name))
			return;

		if( m_name )
			delete []m_name;

		// Validate the pointer after allocating if necessary or put try/catch if exception enabled
		m_name = new char[strlen(name)+1]; 
		strcpy(m_name,name);
	}
	~test()
	{
		if( m_name ) 
                     delete [] m_name;
	}
	void display()
	{
		cout<<m_name<<endl;
	}
};

-Sarath.
"Great hopes make everything great possible" - Benjamin Franklin

My blog - Sharing My Thoughts, An Article - Understanding Statepattern

Re: Is there any memory leak in this code?

SRKSHOME22-Sep-08 20:53

SRKSHOME

22-Sep-08 20:53

Thanks for your better code reply.

problem in copy .exe file

vcprog22-Sep-08 18:56

vcprog

22-Sep-08 18:56

Hi All

I have a problem to copy .exe file.I am useing

GetLastError()

then found error no.32 and 3.
error No. 3 show

The system cannot find the path specified.

And Error no. 32 show

The process cannot access the file because it is being used by another process.

Code is

void On_FileAdded(const CString & strFileName)
{

    USES_CONVERSION;

    CString CStrfilename=strFileName;

    char* charfilename;

    charfilename=CStrfilename.GetBuffer();

    LPCTSTR lp;

    //lp=charfilename;

    lp=CStrfilename;

    PathSkipRoot(lp);

    CString cs = "C:\\Backup\\";
    cs += PathSkipRoot(lp);
    CString st;

//  CopyFile(st, cs,TRUE);
    //AfxMessageBox(st);

if ( CopyFile(strFileName, cs, TRUE) != TRUE)
{
    DWORD dwError = GetLastError();
    CString szMsg;
    szMsg.Format("Error number %d", dwError);
    AfxMessageBox(szMsg);
}
else
{
    AfxMessageBox("Success");
}

    CopyFile(strFileName, cs,TRUE);

}

Plz help me

Re: problem in copy .exe file

_AnsHUMAN_ 22-Sep-08 19:01

_AnsHUMAN_

22-Sep-08 19:01

vcprog wrote:
if ( CopyFile(strFileName, cs, TRUE) != TRUE)

Did you check the contents of strFileName and cs when you use them in CopyFile.

vcprog wrote:
else
{
AfxMessageBox("Success");
}
CopyFile(strFileName, cs,TRUE);

}

BTW why do you wan't to do CopyFile again?

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: problem in copy .exe file

vcprog22-Sep-08 19:22

vcprog

22-Sep-08 19:22

Thx's for reply

yes i check the contents of strFileName and cs both are right.

And when comment these line

CopyFile(strFileName, cs,TRUE);

then file is not not copy..

Plz help me

Re: problem in copy .exe file

Hamid_RT22-Sep-08 19:34

Hamid_RT

22-Sep-08 19:34

Did you try with SHFileOperation?

Re: problem in copy .exe file

vcprog22-Sep-08 19:38

vcprog

22-Sep-08 19:38

No i have no idea about SHFileOperation..

Can you give me example..

Plz help me

Re: problem in copy .exe file

Mahesh Kulkarni22-Sep-08 19:49

Mahesh Kulkarni

22-Sep-08 19:49

ShFileOperation Demo[^]

The secret of life is not enjoyment
but education through experience.
- Swami Vivekananda.

Re: problem in copy .exe file

Hamid_RT22-Sep-08 19:50

Hamid_RT

22-Sep-08 19:50

Like this:

TCHAR m_Files[256];
    sfo.wFunc = FO_COPY;
    sfo.hwnd = NULL;
    sfo.pFrom = m_Files;
    sfo.pTo = "c:\\Pics";
    sfo.fFlags = FOF_SILENT | FOF_NOCONFIRMATION | FOF_NOCONFIRMMKDIR;

    hr = SHFileOperation(&sfo);

Re: problem in copy .exe file

Rajesh R Subramanian22-Sep-08 19:44

Rajesh R Subramanian

22-Sep-08 19:44

vcprog wrote:
The process cannot access the file because it is being used by another process.

Which part of this error message do you not understand? Roll eyes | :rolleyes:

Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche

.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]

Re: problem in copy .exe file

vcprog22-Sep-08 19:47

vcprog

22-Sep-08 19:47

yes you are right i am not understand where is error showing?Can you help me?

Re: problem in copy .exe file

Rajesh R Subramanian22-Sep-08 19:56

Rajesh R Subramanian

22-Sep-08 19:56

The error means that this particular file is being exclusively locked by another process. So, until that process would release this lock, you will not be able to copy this file. You may try copying some other file to verify this.

See if this[^] helps.

Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal - Friedrich Nietzsche

.·´¯`·->Rajesh<-·´¯`·.
[Microsoft MVP - Visual C++]

Re: problem in copy .exe file

vcprog22-Sep-08 20:19

vcprog

22-Sep-08 20:19

Sir it's not help me..Plz tell me how can i solve that problem..

Plz help me

Re: problem in copy .exe file

Hamid_RT22-Sep-08 20:43

Hamid_RT

22-Sep-08 20:43

BTW I found this article for you.Copy, Move and Delete files and directories without using SHFileOperation[^]. Wink | ;)

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