Re: delete operator override - C / C++ / MFC Discussion Boards

Abyss31-Oct-08 6:21

31-Oct-08 6:21

I'm trying to override the global delete operator.

void operator delete(void* pAddr)
{
   ...
}

In this method I do some work and then I would like to call the default delete. However

::delete(pAddr)

always call my delete operator. In my code I have to use delete p; which should call my operator but within my operator I would like to call the default system defined delete operator.

Any idea how to call (obtain) the default delete operator?

Thanks,
Abyss

Re: delete operator override

David Crow31-Oct-08 7:00

David Crow

31-Oct-08 7:00

Abyss wrote:
In this method...I would like to call the default delete.

How about calling free(pAddr) instead?

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: delete operator override

Abyss31-Oct-08 7:07

Abyss

31-Oct-08 7:07

Not sure if it is OK. My understanding is that a pointer allocated by new operator should be freed by delete and call free on the pointer can cause problems...

Re: delete operator override

David Crow31-Oct-08 7:21

David Crow

31-Oct-08 7:21

Abyss wrote:
My understanding is that a pointer allocated by new operator should be freed by delete and call free on the pointer can cause problems...

True, but since you are also overriding the global new operator (hint: you are doing this, aren't you?), that is not an issue.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: delete operator override

CPallini31-Oct-08 7:24

CPallini

31-Oct-08 7:24

You're too fast...
Big Grin | :-D

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]

Re: delete operator override

Bram van Kampen1-Nov-08 15:06

Bram van Kampen

1-Nov-08 15:06

delete is a Keyword, NOT a global function Smile | :)

Bram van Kampen

Re: delete operator override

CPallini31-Oct-08 7:24

CPallini

31-Oct-08 7:24

DavidCrow wrote:
you are doing this, aren't you?

Re: delete operator override

Bram van Kampen1-Nov-08 15:04

Bram van Kampen

1-Nov-08 15:04

delete is a keyword, not a global function!!!
Smile | :)

Bram van Kampen

Re: delete operator override

CPallini31-Oct-08 7:23

CPallini

31-Oct-08 7:23

Probably you can't. Furthermore, if you override delete then you've also to override new, see, for instance [^].

Smile | :)

Re: delete operator override

Bram van Kampen1-Nov-08 14:25

Bram van Kampen

1-Nov-08 14:25

Hmm.

It strikes me that you have reached a language boundary.

Under the cpp model, you can only override functions as follows:;
Member Functions in a Derrived Class with the same Param list,
Member Functions in your original + Derrived Class class with different Param Lists.
Global Functions with different parameter lists.

'delete' is not a global function, but a keyword like 'if' and 'for'
you can override it with your own implementation, but, if you do so, you replace it. That is only possible because it is a keyword. If it were a global function, you would not be able to re-define it at all. (you'd get all types of linker errors)

My advice is: Re-Design the Code.

regards,

Smile | :)

Bram van Kampen

how many files can be opened in windows OS at a Time ?

paul crescent31-Oct-08 3:08

paul crescent

31-Oct-08 3:08

Dear friends

please tell the answer

how many files can be opened in windows OS at a Time ?

by

paul

Re: how many files can be opened in windows OS at a Time ?

toxcct31-Oct-08 3:24

toxcct

31-Oct-08 3:24

there is no such a limitation AFAIK.

IIRC, there is one at Process Level, but I don't know its limit.
I believe you can find it as a #define in some header file (not sure however)

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Re: how many files can be opened in windows OS at a Time ?

paul crescent31-Oct-08 3:41

paul crescent

31-Oct-08 3:41

I am asked by Micorsoft Technical Interview Cry | :((

Re: how many files can be opened in windows OS at a Time ?

Iain Clarke, Warrior Programmer31-Oct-08 4:54

Iain Clarke, Warrior Programmer

31-Oct-08 4:54

Well, then they're interviewing you, not us..

Or you could argue that this is testing your ability to research things.

My answer would be: "If you need to know, your design is wrong".

Iain.

Re: how many files can be opened in windows OS at a Time ?

CPallini31-Oct-08 4:10

CPallini

31-Oct-08 4:10

Does this [^] help?
Smile | :)

Re: how many files can be opened in windows OS at a Time ?

Roger Stoltz31-Oct-08 5:19

Roger Stoltz

31-Oct-08 5:19

paul crescent wrote:
how many files can be opened in windows OS at a Time ?

The limit referred to probably is the lowio level of the C Runtime Library which is 2,048 simultaneously opened. Read more here[^].
There are other limitations such as on stdio level, which is 512 by default but can be increased with a call to

<a href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx">_setmaxstdio()</a>[<a href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx" target="_blank" title="New Window">^</a>]

to a maximum of 2,048.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Re: how many files can be opened in windows OS at a Time ?

Bram van Kampen1-Nov-08 14:50

Bram van Kampen

1-Nov-08 14:50

Well,

There are no more hard and fast limits, unlike DOS, where you had to specify how many. The answer is, that it depends on resources, and what's consumed with each file. It also depends on resources required by the OS.
One answer would be, a Multitude more under XP than under Vista, on the same hardware. The other answer is Depends on the response time reqired. If you measure response time of the computer in weeks, the number would be determined by your disk size

Smile | :)

Bram van Kampen

Registry problem(UAC Off or On)

MsmVc31-Oct-08 2:20

MsmVc

31-Oct-08 2:20

Hi All

I am try to edit regedit values in VISTA OS.It is working when UAC off.But when UAC is on then it's not working.Code is here

HKEY hKey;
    DWORD dwDisp = 0;
    LPDWORD lpdwDisp = &dwDisp;
    CString l_strExampleKey = "SYSTEM\\CurrentControlSet\\Services\\USBSTOR";
    CString l_strDWordSample = "Start";
    DWORD dwVal = 4;
	
	LONG iSuccess = RegOpenKeyEx (HKEY_LOCAL_MACHINE, "SYSTEM\\CurrentControlSet\\Services\\USBSTOR", 0L, KEY_READ , &hKey);
	if(iSuccess == ERROR_SUCCESS)
       {
		   
			RegCreateKeyEx( HKEY_LOCAL_MACHINE, l_strExampleKey, 0L,NULL, REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, NULL, &hKey,lpdwDisp);
            RegSetValueEx (hKey, l_strDWordSample, 0L, REG_DWORD,(CONST BYTE*) &dwVal, sizeof(DWORD));
	
		}
	      	
	RegCloseKey(hKey);

Plz help me where i am wrong..

Thanks in advance Rose | [Rose]

Re: Registry problem(UAC Off or On)

Rajesh R Subramanian31-Oct-08 2:42

Rajesh R Subramanian

31-Oct-08 2:42

See here[^]

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

ASCII to UNICODE

CodingLover31-Oct-08 2:17

CodingLover

31-Oct-08 2:17

Hi all,

I'm wired with this two days now.

In a chr* buffer I got a int in ASCII.

I want to convert into UNICODE and attach a stringstream, which is a UNICODE stream.

How can I do it.

Help really appreciate.
Thanks a lot,

I appreciate your help all the time...
CodingLover Smile | :)

Re: ASCII to UNICODE

David Crow31-Oct-08 2:47

David Crow

31-Oct-08 2:47

CodingLover wrote:

I want to convert into UNICODE...

Check out wchar_t.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Re: ASCII to UNICODE

CPallini31-Oct-08 2:51

CPallini

31-Oct-08 2:51

Check out [^] and [^].
Smile | :)

Re: ASCII to UNICODE

Nishad S31-Oct-08 2:57

Nishad S

31-Oct-08 2:57

i think, you need to convert the number to string (like "123" for example) first using wsprintf, or any similar function like that. If not, if the value is zero, then it may be taken as the end of string (depends upon how you use the string stream).

- NS -
[ODBaseBtn]

Re: ASCII to UNICODE

CodingLover31-Oct-08 3:01

CodingLover

31-Oct-08 3:01

Can you explain it with a simple example, please.

I appreciate your help all the time...
CodingLover Smile | :)

Re: ASCII to UNICODE - What I've done so far

CodingLover31-Oct-08 3:12

CodingLover

31-Oct-08 3:12

Here what I have done so far.

<br />
<br />
	int temp = InMsg[0]; // In the buffer 0th byte contain the int value<br />
<br />
	stringstream str(ios::in|ios::out|ios::binary);<br />
	if(CopyTo(str) == 0) // This return the stream correctly<br />
	{<br />
		wchar_t* results = new wchar_t[1];<br />
		swprintf(results, L"%d", temp);<br />
		<br />
		InMsg.Attach(results, 0); // I'm stuck here<br />
	}<br />

My attach function like this.

<br />
bool CRfMessage::Attach(istream& str, const UINT offset)<br />
{<br />
	size_t		buffer_size;<br />
<br />
	if(str.bad()) <br />
		return false;<br />
<br />
	str.seekg(0,ios_base::end);<br />
<br />
	buffer_size = str.tellg();<br />
<br />
	char* payload = (char*)AdjustDataSize((UINT)buffer_size+offset);<br />
<br />
	//	move to begin and read in to message buffer<br />
	str.seekg(0,ios_base::beg).read(payload+offset,buffer_size);<br />
<br />
	return true;<br />
}<br />

I appreciate your help all the time...
CodingLover Smile | :)

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