C / C++ / MFC

Re: overloading new operator

7-May-07 1:42

ragavan wrote:
why it is necessary to overload new and delete operator

to put some extra printf() inside them for instance !? Wink | ;)

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James R. Twine7-May-07 3:12

James R. Twine

7-May-07 3:12

   One (the only?) reason is when the objects need to be allocated in a non-standard way. For example, for performance reasons, you may be using per-thread heaps so as to avoid heap contention in a multi-threaded application (if the application is allocation intensive).

   Or if you have to allocate lots of smaller-sized objects (< 16-32 bytes) and you need to optimize the allocations by allocating larger blocks and then chunking them yourself. Combining the Win32 heap's and C-RTL's overhead, a heap allocation can have between 20-32 bytes of overhead. So if you need to allocate one million objects of 8 bytes each, this overhead (both space and execution time) can start to add up quickly.

   Granted, the average everyday developer does not need to be (or simply is not) concerned with such things, but those are some reasons I have done it in the past.

   Peace!

-=- James
Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
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CListCtrl

study.sourabh7-May-07 0:43

study.sourabh

7-May-07 0:43

Hi,

i have a CListView style of which is in report.
how can i get the cell which user selected?
Is it posible to change the icone used for check box ?

thanks in advance
Sourabh

sourabh

Hans Dietrich7-May-07 1:31

Hans Dietrich

7-May-07 1:31

study.sourabh wrote:
how can i get the cell which user selected?

In my XListCtrl, I have the function:

int CXListCtrl::GetCurSel()
{
	POSITION pos = GetFirstSelectedItemPosition();
	int nSelectedItem = -1;
	if (pos != NULL)
		nSelectedItem = GetNextSelectedItem(pos);
	return nSelectedItem;
}

Note that this returns the selected row. To find out which column was clicked, you can handle the NM_CLICK or LVN_COLUMNCLICK messages.

study.sourabh wrote:
Is it posible to change the icone used for check box ?

Yes, you can handle the NM_CUSTOMDRAW message and draw your own. There are examples here on CP that will help.

Best wishes,
Hans

study.sourabh7-May-07 3:03

study.sourabh

7-May-07 3:03

hi Hans,
Thanks for the help.
But LVN_COLUMNCLICK message will give the colem which was selected in the header of CListCtrl right?
i wanted to know to which cell in the row user selected.Is it posible to get information regarding that?
thnanks

sourabh

Hans Dietrich7-May-07 3:36

Hans Dietrich

7-May-07 3:36

As I said, you can handle the NM_CLICK message. Here is some sample code:

void CXListCtrlTestDlg::OnClick(NMHDR* pNMHDR, LRESULT* pResult)
{
	LPNMITEMACTIVATE pNMIA = reinterpret_cast<LPNMITEMACTIVATE>(pNMHDR);
	int nItem = -1;
	int nSubItem = -1;
	if (pNMIA)
	{
		nItem = pNMIA->iItem;
		nSubItem = pNMIA->iSubItem;
	}

	if (nItem >= 0 && nSubItem >= 0)
	{
		CString strText = m_List.GetItemText(nItem, nSubItem);
		Log(_T("OnClick at (%d,%d):  '%s'"), nItem, nSubItem, strText);
	}

	*pResult = 0;
}

Best wishes,
Hans

NP-complete riddle/algorithm

study.sourabh7-May-07 18:02

study.sourabh

7-May-07 18:02

Hi Hans,

Thank you very much.
It works i get the column which is clicked.

sourabh

Yariv6-May-07 23:56

6-May-07 23:56

I'm looking for a c/c++ solution for the following NP-completeness problem:

Write a function that gets an array of integers, its size and an integer. The function should return true if the sum of any subset of the array members is equalt to the integer. For example, if the array is 1,3,5,6 then possible sum are 4(1+3),11(5+6),9(1+3+5). If the intefger is 20 then the function returns false (no way of getting a sum higher than 15:1+3+5+6)

C Function declaration for example: bool is_subset(int* pArray,int nSize,int Sum)
MFC function declaration for example: BOOL IsSubset(const CUIntArray& Array,UINT Sum)

Thanks

toxcct7-May-07 0:04

7-May-07 0:04

have you already started to code something by yourself on this assignement ?
or are you a bit too lazy to expecting us to do your homework ? Poke tongue | ;-P

also, please ask a specific question; asking for a whole job is all but what will bring you some help, because people here are not paid for helping, and get iritated by lazy questions...

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Yariv7-May-07 8:47

7-May-07 8:47

Please look at my reply to Hans...
Thanks

Hans Dietrich7-May-07 1:36

Hans Dietrich

7-May-07 1:36

That sounds like a neat assignment. Just out of curiosity, what grade level are you in?

BTW, there are more possible sums than what you list.

Best wishes,
Hans

Yariv7-May-07 8:46

7-May-07 8:46

Luckily I'm not a student. I guess that if I was I had the answer because it sounds like a school assignment. I'm a shame to admit that when I was this question was introduced to me I started to write it using a recursive function, but I got stuck because it started to be too complex. It was then that I thought there must be a simple (school) solution for this, as this is an academic riddle (just like the traveling salesman). I thought mayeb someone here has the insight...

Yariv7-May-07 12:43

ScrollBar Presence in ListBox ?

7-May-07 12:43

Incase someone interested, here is a simple solution. I have no idea why I got stuck from the first place:

<br />
BOOL IsSum(const CUIntArray& Array,UINT Sum) const<br />
{<br />
	for(int i=0;i < Array.GetSize();i++)<br />
	{<br />
		if(Array[i] == Sum)<br />
			return TRUE;<br />
		else if(Array[i] < Sum)<br />
		{<br />
			if(CheckSum(Array,Sum,i,Array[i]))<br />
				return TRUE;<br />
		}<br />
	}<br />
	return FALSE;<br />
}<br />
<br />
BOOL CheckSum(const CUIntArray& Array,UINT Sum,int nIndex,UINT SoFar) const<br />
{<br />
  for(int i=nIndex+1;i < Array.GetSize();i++)<br />
 {<br />
   if((SoFar+Array[i]) == Sum)<br />
     return TRUE;<br />
   else if((SoFar+Array[i])<Sum)<br />
   {<br />
      if(CheckSum(Array,Sum,i,SoFar+Array[i]))<br />
         return TRUE;<br />
   }<br />
 }	<br />
 return FALSE;<br />
}<br />

sayed_76-May-07 23:30

sayed_7

6-May-07 23:30

Hi I have one enquiry. I am a novice in mfc. Using one listbox. In that sometimes I have less data, some times lot of data. Depending on that the scrollbar comes automatically. So my enquiry is that is there any way to know the presence of scrollbar in the listbox? If so how to do that ? Any suggession will be highly helpful.

Regardly
Confused | :confused:

Sayed

Trusted

Re: ScrollBar Presence in ListBox ?

prasad_som6-May-07 23:44

prasad_som

6-May-07 23:44

Use GetScrollBarInfo. Refer SCROLLBARINFO-->rgstate.
Your code would be something like this,

SCROLLBARINFO info;
GetScrollBarInfo(OBJID_VSCROLL,&info);
if (info.rgstate[0] & STATE_SYSTEM_OFFSCREEN)
{
  //vertical scroll bar is present for window, but is not displayed
}

Prasad
MS MVP - VC++

How to get PID / Process Name from Task Manager

SNI6-May-07 23:11

SNI

6-May-07 23:11

Hi,
I am trying to kill process from task manager using "End Process" in "Processes" tab. But I tried to get the handle / PID of the process that I have selected to terminat. I would like to know how to get the handle / PID of the process that I am trying to terminate.
I tried to use TerminateProcess API to handle this. But I am not able to get handle for the killing process (e.g. winword.exe).

Anything on this will help.

Thanks

SNI

jhghjghj

Re: How to get PID / Process Name from Task Manager

SNI6-May-07 23:16

SNI

6-May-07 23:16

I am looking this in VC++.

jhghjghj

Re: How to get PID / Process Name from Task Manager

prasad_som6-May-07 23:24

prasad_som

6-May-07 23:24

Probably, you are looking code some thing similar to posted[^] by this poster.

Prasad
MS MVP - VC++

Re: How to get PID / Process Name from Task Manager

ThatsAlok16-May-07 20:00

ThatsAlok

16-May-07 20:00

SNI wrote:
I am looking this in VC++.

please have a look at Process32First and Process32Next

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

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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how to convert the string type into double type? (vs 2005)

sync_austin6-May-07 23:09

sync_austin

6-May-07 23:09

double GetInvestmentAmount()
{
Console::Write(L"How much money do you want to invest? ");

String^ input = Console::ReadLine();
double amount = \\ i want to convert the 'input 'into the double type
return amount;
}

how can I convert the " String ^ input" into the double type. Thanks in advance.
I've tried "safe_cast<double>(Console::ReadLine())" and " Covert.ToDouble(*input)" but it just doesn't work ==

Re: how to convert the string type into double type? (vs 2005)

_AnsHUMAN_ 6-May-07 23:15

_AnsHUMAN_

6-May-07 23:15

use atof()

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

_AnShUmAn_

Re: how to convert the string type into double type? (vs 2005)

toxcct6-May-07 23:19

Re: how to convert the string type into double type? (vs 2005)

6-May-07 23:19

anshu, don't encourage bad post by answering them, please Wink | ;)

there are enough of them these days, and especially today ! Sigh | :sigh:

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_AnsHUMAN_ 6-May-07 23:24

_AnsHUMAN_

6-May-07 23:24

Hmm!!!! Rightly Said. Roll eyes | :rolleyes:

Never thought that way Sniff | :^)

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

_AnShUmAn_

Re: how to convert the string type into double type? (vs 2005)

Mark Salsbery7-May-07 5:20

Mark Salsbery

7-May-07 5:20

But he gave the OP an unmanaged solution! Wink | ;)

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Re: how to convert the string type into double type? (vs 2005)

toxcct7-May-07 5:26