Re: Delete object, necessaray?? - C / C++ / MFC Discussion Boards

Maximilien14-Dec-04 2:27

14-Dec-04 2:27

yes.

if there's no variable assigned to it?

more so in that case ... me think that if you have allocated objects hanging around, you would need to clean them up.

how do you have them ? calling a function that allocates something and return it and you don't use it ?

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Delete object, necessaray??

V.14-Dec-04 3:00

14-Dec-04 3:00

if you use new you call delete ALWAYS.

Even better would be to do this:

Object *x = new Object();<br />
<br />
//... do things with x<br />
<br />
delete x;<br />
x = NULL;

This way you do not accidentally call x that points to something else than Object. (because the memory to which the pointer points to is overwritten)

good luck.

"If I don't see you in this world, I'll see you in the next one... and don't be late." ~ Jimi Hendrix

Re: Delete object, necessaray??

toxcct14-Dec-04 4:29

toxcct

14-Dec-04 4:29

V. wrote:
if you use new you call delete ALWAYS.

wrong. Windows can do it itself, but that's a very bad way to program...

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: Delete object, necessaray??

V.14-Dec-04 4:38

14-Dec-04 4:38

ok I correct myself:

If you're a good programmerand if you use new you call delete ALWAYS Big Grin | :-D

"If I don't see you in this world, I'll see you in the next one... and don't be late." ~ Jimi Hendrix

Re: Delete object, necessaray??

toxcct14-Dec-04 4:53

toxcct

14-Dec-04 4:53

much better ! Big Grin | :-D

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: Delete object, necessaray??

David Crow14-Dec-04 5:24

David Crow

14-Dec-04 5:24

toxcct wrote:
Windows can do it itself...

Only if the application exits or is terminated. Things like services are designed to run for long periods of time so a call to delete is a requirement.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: Delete object, necessaray??

tpndtbk14-Dec-04 3:30

tpndtbk

14-Dec-04 3:30

Thank you for your help.

Another related question..
if I have the class:

class ObjectA
{
ObjectB b;
}

ObjectA a = new objectA();
When i detele ObjectA (delete a), do I have to delete ObjectB (delete b)? or is it implicitly deleted?

Re: Delete object, necessaray??

tpndtbk14-Dec-04 3:34

tpndtbk

14-Dec-04 3:34

And in the following case:

I have
ObjectA a = new ObjectA();

//...

Do I have to delete a (delete a) before I create a new ObjectA and assign it to a??
a = new ObjectA();

Re: Delete object, necessaray??

Jon Hulatt14-Dec-04 4:19

Jon Hulatt

14-Dec-04 4:19

It seems like you need to do some reading on memory allocation in C / C++

When you declare an object like this:-

ObjectA theObject;

It is created for you, and it will be removed automatically when it goes out of scope.

When you declare an object like this:-

ObjectA *thePointerToObject = new ObjectA();

You are doing three things:- creating a pointer (which will be removed for you), creating a new instance of ObjectA (which it is your duty to clean up), and setting your new pointer to point to the new object.

This really is basic C++. *Any* C++ tutorial book/site will explain this; go out there are read up!

using System.Beer;

Re: Delete object, necessaray??

David Crow14-Dec-04 5:36

David Crow

14-Dec-04 5:36

Stack-based variables, as opposed to heap-based variables (i.e., those created with new), are cleaned up when the variable goes out of scope.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: Delete object, necessaray??

toxcct14-Dec-04 4:36

toxcct

14-Dec-04 4:36

you should never wonder if the system will perform such operation for you. if you own the object, then take use to delete it when you don't need it anymore.
if one day you come to work on poor operating systems which don't do this for you, or worse, systems that don't have any OS, you will have serious lacks of memory !!!
think of it...

TOXCCT >>> GEII power
[toxcct][VisualCalc]

a ftp server where download XP for free

Anonymous14-Dec-04 1:21

Anonymous

14-Dec-04 1:21

i am looking for a ftp server where i can download windows xp for free because i need to reinstall xp and dont have a copy

Re: a ftp server where download XP for free

Antony M Kancidrowski14-Dec-04 1:42

Antony M Kancidrowski

14-Dec-04 1:42

Wrong forum

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Walliams (Little Britain)

Re: a ftp server where download XP for free

Jon Hulatt14-Dec-04 4:20

Jon Hulatt

14-Dec-04 4:20

Wrong site and attitude too.

using System.Beer;

Re: a ftp server where download XP for free

toxcct14-Dec-04 4:27

toxcct

14-Dec-04 4:27

give me your names and address, i'll send it to you... Laugh | :laugh:

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Serialization

AslFunky14-Dec-04 1:17

AslFunky

14-Dec-04 1:17

HI people;),
Please help me out with this one.
I was working on a project for creating a Text Editor.
Everything was going on fine, until i serialized my data.
What i am doing is that i have an CArray of CString, so that a particular index in the array represents one line of the text-editor.
While serializing, i have to use a loop to write the CString of every index of the array to a file. But the problem with serializing is that it breaks out of the loop, when it encounters a \n. In my program, each line is ended by a \r\n.
I have even tried using Write of CArchive. But it doesn't work.
Is there any way in which i could serialize my data to the file?
Cry | :((

Help.... SOS..... Cry | :((

Thanks in advance. Smile | :)

AslFunky

Re: Serialization

Ravi Bhavnani14-Dec-04 7:52

Ravi Bhavnani

14-Dec-04 7:52

My serialization tutorial[^] may help.

/ravi

My new year's resolution: 2048 x 1536
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Capturing BitMap using DirectShow

tspramod14-Dec-04 1:10

tspramod

14-Dec-04 1:10

Using DirectShow , If i need to capture bitmap from Live video
what is the interface i need to use..??

Also, Is there any interface thru which i can the id of the connected hardware
( webcam or handycam in my case..!! )

Thanks in advance,
Pramod.

rotating a bitmap

Arrun13-Dec-04 23:55

Arrun

13-Dec-04 23:55

hi I am doing a pattern matching program uisng MFC, could anyone help me with the equations thats necessary to rotate the bitmap.

Re: rotating a bitmap

namaskaaram14-Dec-04 0:39

namaskaaram

14-Dec-04 0:39

i think there r already functionz that do those.....
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/_gdiplus_rotating_reflecting_and_skewing_images_usecsharp.asp[^]

hope that helpz!!!!!
Big Grin | :-D

Exception in CPropertySheet::OnInitDialog()

Avya13-Dec-04 23:52

Avya

13-Dec-04 23:52

Hi all...
plz read it completely...may be it will be helpfull for you also...

I am facing one problem, I get exception in the InitDialog of CPropertySheet()...

I have a Class named CXPropertySheet which is derived from CPropertySheet, I need this class because I want some extra effects and capabilites in property pages and propertysheet, like resizability painting background color etc...
I also have one class derived from CTabCtrl, which I use to paint tab buttons on tab control. I subclass this class to tab control of CXPropertySheet...

in the InitDialog of main dialog...
m_pPropertySheet = new CXPropertySheet("Logkey", this);
//++ Add pages to the property sheet
m_pPropertySheet->AddPage(&m_firstPage);
m_pPropertySheet->AddPage(&m_secondPage);
.
.
//++ display the property sheet...
m_pPropertySheet->Create(this, WS_CHILD | WS_VISIBLE);
//++ Modify the style,
m_pPropertySheet->ModifyStyleEx(0, WS_EX_CONTROLPARENT);
m_pPropertySheet->ModifyStyle(0, DS_CONTROL);
///////////////////////////////////////////////////////////////////////////////////////

In the InitDialog of the CXPropertySheet....to make it resizable…I wrote this code…

// I get exception here...
writeToTrace("CPropertySheet::OnInitDialog");
BOOL bResult = CPropertySheet::OnInitDialog();

writeToTrace("CXPropertySheet::OnInitDialog");
/* Subclass the tab control. */
m_myTabCtrl.SubclassWindow(GetTabControl()->m_hWnd);
writeToTrace("Subclassed the tab control");

/* Make it owner drawn. */
m_myTabCtrl.ModifyStyle(0, TCS_OWNERDRAWFIXED);

If I run it in debug it runs fine....It runs with Release build as well but in very inconsistent manner... but only on my machine...which is Win2000 professional...

I will be very grateful if anybody could give your thought for this problem, I am sorry if I have not described the problem properly...

thanx and regards...
Avya

Avya.

Re: Exception in CPropertySheet::OnInitDialog()

Antony M Kancidrowski14-Dec-04 1:12

Antony M Kancidrowski

14-Dec-04 1:12

What is the exact exception you are getting?

Ant.

I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Walliams (Little Britain)

Re: Exception in CPropertySheet::OnInitDialog()

Avya15-Dec-04 21:47

Avya

15-Dec-04 21:47

I dont know what that exception was....but fortunately I solved the prob....
I think the problem was I was deriving property sheet from CPropertySheet nad the property pages from my other class, which is derived from CPropertyPage, so in InitDiaog of Properysheet it was not able to add the pages, I suppose. Then I changed the aproach and derived all the property pages from CProperyPage...Noe it is working fine...
Anyways thanks for reply...I would like to get tou comment on this...why it may give exception if the propery pages arent derived directly from CProperyPage...

Thanks and regards

Avya.

Delete Temporary Internet File

Rajesh_K_Sharma13-Dec-04 23:06

Rajesh_K_Sharma

13-Dec-04 23:06

Hi all,
I want to delete temp internet file placed in the directory
C:\Documents and Settings\user1\Local Settings\Temporary Internet Files.

Is any Api available in vc++ which can do this work?

rajesh

Re: Delete Temporary Internet File

Ravi Bhavnani14-Dec-04 0:30

Ravi Bhavnani

14-Dec-04 0:30

See _unlink(), DeleteFile() and CFile::Remove().

/ravi

My new year's resolution: 2048 x 1536
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