Re: delete pointer. - C / C++ / MFC Discussion Boards

Re: delete pointer.

toxcct13-Jun-06 21:51

toxcct

13-Jun-06 21:51

and what is the error ?????

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: delete pointer.

see me13-Jun-06 22:08

see me

13-Jun-06 22:08

exception is occuring.

yours faithfully
ajeeshcv

Re: delete pointer.

toxcct13-Jun-06 22:10

toxcct

13-Jun-06 22:10

Ajeesh c v wrote:
exception is occuring.

DAMNNNNN !!! WHICHHHH ?????

if you don't provide some descriptions of your error case, how can one help you ?? Unsure | :~

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: delete pointer.

see me13-Jun-06 22:16

see me

13-Jun-06 22:16

ok...
I think the problem is occuring due to this reason.

am initializing the pointer from thread...adn try to delete it from another thread..

if there is any chance of occuring exception????

Please help me...

yours faithfully
ajeeshcv

Re: delete pointer.

toxcct13-Jun-06 22:19

toxcct

13-Jun-06 22:19

as far as you don't answer my questions, i don't help you furthermore.

Sleepy | :zzz:

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: delete pointer.

Viorel.13-Jun-06 22:23

Viorel.

13-Jun-06 22:23

I think this causes problems if your project’s configuration does not allow multi-threading. You should open the project’s properties dialog and be sure that the C/C++ --> Code Generation --> Runtime Library option contains a right value related to multi-threading. Then rebuild the application.

Re: delete pointer.

see me13-Jun-06 22:29

see me

13-Jun-06 22:29

Thank you...
I don't know it will work or not.
Let me check.

yours faithfully
ajeeshcv

Re: delete pointer.

jhwurmbach21-Jun-06 22:59

jhwurmbach

21-Jun-06 22:59

Ajeesh c v wrote:
am initializing the pointer from thread...adn try to delete it from another thread

May one thread still be accessing the memory you just deleted?
Maybe using smart-pointers (like those from boost.org)[^]can help you?
Or at least an object which can delete itself via a member function?

"We trained hard, but it seemed that every time we were beginning to form up into teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by reorganising: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralisation."

-- Caius Petronius, Roman Consul, 66 A.D.

Re: delete pointer.

Cedric Moonen13-Jun-06 22:10

Cedric Moonen

13-Jun-06 22:10

That's a very clear description of the problem Unsure | :~

The solution is: you did something wrong.

Cédric Moonen
Software developer

Charting control

Re: delete pointer.

see me13-Jun-06 22:21

see me

13-Jun-06 22:21

Thats a very precious information for me.
Thank you..

yours faithfully
ajeeshcv

Re: delete pointer.

Cedric Moonen13-Jun-06 21:54

Cedric Moonen

13-Jun-06 21:54

What is the exact error ?

Maybe your pointer points to an invalid address. You probably left it uninitialized and then try to delete it.

Cédric Moonen
Software developer

Charting control

Re: dlete pointer. [modified]

Viorel.13-Jun-06 21:48

Viorel.

13-Jun-06 21:48

Possible causes:

un-initialized pointer, like int * p; delete p;
pointer does not point to an object created with new: int x; int * p = &x; delete p;
multiple execution of delete: int * p = new int; delete p; delete p;
pointed zone was altered by other code: int * p = new int; memset(p-100, 0, 1000); delete p;

int * p = NULL; delete p;

Re: delete pointer.

see me13-Jun-06 22:05

see me

13-Jun-06 22:05

In my case the above mentioned 4 cases will not be satisfied.
Actual reason is any other.:->

And also as per ur comments
int * p = NULL; delete p;

how the datas will be deleted from the location which is pointed by p initialy.
since u r saying to delete the pointer after asigning the pointer to null. Confused | :confused:

yours faithfully
ajeeshcv

Re: delete pointer.

toxcct13-Jun-06 22:12

toxcct

13-Jun-06 22:12

Ajeesh c v wrote:
int * p = NULL; delete p;

how the datas will be deleted from the location which is pointed by p initialy.
since u r saying to delete the pointer after asigning the pointer to null.

he doesn't say it is the things to do...

the cases enumerated are possible causes for a crash when deleting a pointer Dead | X|

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: delete pointer.

Cedric Moonen13-Jun-06 22:13

Cedric Moonen

13-Jun-06 22:13

Ajeesh c v wrote:
how the datas will be deleted from the location which is pointed by p initialy.
since u r saying to delete the pointer after asigning the pointer to null.

That's probably your problem. When you do this:

int* pTest;
if (pTest)
   delete pTest;

You will have an excpetion because you try to delete memory that is unitianalized (you can only delete memory that has been allocated with new). So, to be sure not to delete this 'unexistant' memory, assign NULL to the pointer. This is safe.

Cédric Moonen
Software developer

Charting control

Re: delete pointer.

Viorel.13-Jun-06 22:16

Viorel.

13-Jun-06 22:16

According to documentation (http://msdn2.microsoft.com/en-us/library/h6227113.aspx[^]), “You can [...] use delete on a pointer with the value 0”.

Therefore instead of

if( p != NULL )
{
    delete p;
    p = NULL;
}

you can use

delete p;
p = NULL;

However, this does not belong to original topic. I think you should put a breakpoint at the line where your block of memory is allocated and the pointer is assigned. Then investigate the pointer’s value and the content of the memory block. Then stop on the line where the pointer is deleted. Check if the pointer contains right address value. Try to use step-be-step execution during deletion. Perhaps the pointer points to an object having destructor, and the problem is within this function.

Re: dlete pointer.

John R. Shaw13-Jun-06 21:50

John R. Shaw

13-Jun-06 21:50

You need to be more specific, what do you mean by delete a pointer? I assume memory pointer, but these days it is hard to say. What compiler of language are you using?

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: dlete pointer.

Hamid_RT13-Jun-06 22:10

Hamid_RT

13-Jun-06 22:10

Can you show how to use pointer and how to declare pointer

whitesky

Re: delete pointer.

see me13-Jun-06 22:27

see me

13-Jun-06 22:27

The pointer is of a dialog.

Initialization:
CMyDialog* pMyDialog;
pMyDialog = new CMyDialog;

pMyDialog->EndDialog(0);

if(pMyDialog)
{
delete pMyDialog;
pMyDialog = 0;
}

yours faithfully
ajeeshcv

Re: delete pointer.

Hamid_RT13-Jun-06 22:51

Hamid_RT

13-Jun-06 22:51

im not sure your problem is this but
how to create dialog? and if you run your code i think you get a error in pMyDialog->EndDialog(0);
now try this and send me if you have a error

<br />
CMyDialog* pMyDialog;<br />
pMyDialog = new CMyDialog;<br />
pMyDialog->Create(IDD_TEST);//id from dialog<br />
pMyDialog->EndDialog(0);<br />
delete pMyDialog ;<br />
pMyDialog = 0;<br />

whitesky

how to know the values for event masks

thathvamsi13-Jun-06 21:12

thathvamsi

13-Jun-06 21:12

Hey ...
I am new inthis area. I am interested in knowing the values for the event masks used in GetCommMask and SetCommMask functions. ie., EV_BREAK = 0x????
How do i know which event is activated or received?
Any help/guide??

Re: how to know the values for event masks

Viorel.13-Jun-06 21:19

Viorel.

13-Jun-06 21:19

You can see these values in WinBase.h file, which is in a subfolder of Visual Studio.

Re: how to know the values for event masks

thathvamsi13-Jun-06 22:37

thathvamsi

13-Jun-06 22:37

hey... thanks for that. this winbase.h file explains lot of my other doubts.

Re: how to know the values for event masks

Hamid_RT13-Jun-06 22:20