C / C++ / MFC Discussion Boards

Chandrasekharan P26-Jun-12 0:21

26-Jun-12 0:21

AFAIK, You can sort maps only by the Key element. I think that is the the point of having maps.

Your scenario might work out some way. but what if 2 different keys has the same values? how will you sort it?

Every new day is another chance to change your life.

Re: sort a map by Value

Roger Stoltz26-Jun-12 0:34

Roger Stoltz

26-Jun-12 0:34

NajaR12 wrote:
Can anybody tell me how to sort a map based on the values.

Why do you want to do that?
Your desire suggests that you have misunderstood the purpose of a map.
The key is supposed to be unique and the value is identified by its corresponding key so you may write code such as in order to retrieve the "box" associated with the key:

C++

Box& box = Map[key];

However, if your "boxes" are unique you may use them as keys, e.g.:

C++

Map[box1] = key2;
Map[box2] = key4;
Map[box3] = key1;
Map[box4] = key3;

Consider using a std::list that is entry-sorted.

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

Re: sort a map by Value

C^hris L^osinger26-Jun-12 1:14

C^hris L^osinger

26-Jun-12 1:14

a map isn't really the right container for this.

if you have pairs that need to be sorted, why not put them into a vector/list of std::pair<key,box> and sort that on box ?

image processing toolkits | batch image processing

Error CXX0052: Member function not found

AmbiguousName25-Jun-12 19:26

AmbiguousName

25-Jun-12 19:26

hello guys... I have a listbox on my dialog. I am debugging my program and getting this error. Here is what I am trying

if(ListBox.GetCount() >= 1)
  //then do some stuff

Now when I select ListCtrl.GetCount() and select Add Watch, it shows me the said error. Now although the problem is solved using following technique but what if I don't want to add unnecessary variables.

int count = ListBox.GetCount();
if(count >= 1)
  //then do some stuff

This world is going to explode due to international politics, SOON.

Re: Error CXX0052: Member function not found

Binu MD25-Jun-12 20:24

Binu MD

25-Jun-12 20:24

Please set your complier optimization option to “Disabled” and try

Re: Error CXX0052: Member function not found

Richard MacCutchan25-Jun-12 22:06

Richard MacCutchan

25-Jun-12 22:06

See here[^]; if the code is inlined then no function exists in the compiled version.

speaking as ...

Re: Error CXX0052: Member function not found

fat_boy26-Jun-12 3:10

fat_boy

26-Jun-12 3:10

That variable would get optimised out in a release build anyway so dont worry about it.

Fastest form of Interprocess communication

ForNow25-Jun-12 6:44

ForNow

25-Jun-12 6:44

I am using named pipes to transfer data between a DOS "C" program and Window MFC
program

In this scenrio the DOS program acts as the server while the Windows program is the Client

The Windows program send a string to the DOS program and the DOS program responds sending across 150 - 300 bytes

Speed is of otmost importance as this a ongoing conversation

I have chosen to use Named pipes

since I am releative newbie

I am wondering what the fastest method of IPC would be

Thanks in advance

Re: Fastest form of Interprocess communication

Albert Holguin25-Jun-12 7:24

Albert Holguin

25-Jun-12 7:24

Probably the fastest would be a shared memory pool... but are you sure you need that speed? A lot of times, people think they need the best of something when they really only need something that is good enough.

For example, even though shared memory would probably be the fastest option, it would probably not be easy to implement across multiple systems, your server and client would always have to be on the same machine (and by default, same OS), whereas if you used something more versatile like sockets, you could have your system work across different machines (or in the same one, no difference), different operating systems, different states, and even different countries.

So, make sure that you really need all that speed. For example, a phone conversation can be transmitted over sockets with no issue, but digitized IF (if you know what that means) could only go up to certain rates efficiently over a network.

How to get the temperature from my aplication?

MroMarcosKim25-Jun-12 6:01

MroMarcosKim

25-Jun-12 6:01

Hello...

Please ask some help to get the temperature of CPU....

If you have some class o sample..
Please help me.. Thanks a lots...

Re: How to get the temperature from my aplication?

Software_Developer25-Jun-12 6:24

Software_Developer

25-Jun-12 6:24

[Here] and [here].

This class and its members cannot be used in applications that execute in the Windows Runtime.

bob1697225-Jun-12 5:10

bob16972

25-Jun-12 5:10

I keep seeing this "note" as I browse through the MSDN for Visual C++ 2012 (i.e. MFC classes, ATL, etc...)

What exactly does this imply for a Native Code programmer? (The more I read about the WinRT, the more confused I get)
Will a traditional MFC application just work in Windows 8?

modified 25-Jun-12 11:23am.

Re: This class and its members cannot be used in applications that execute in the Windows Runtime.

Albert Holguin25-Jun-12 7:36

Albert Holguin

25-Jun-12 7:36

bob16972 wrote:
What exactly does this imply for a Native Code programmer?

Nothing really... it's not like the WinAPI is going away.

bob16972 wrote:
Will a traditional MFC application just work in Windows 8?

They should, accessing desktop applications is not going away. There was an article about this not too long ago stating the intent for Visual Studio to keep supporting desktop application development, which means it will keep getting supported in Windows.

Re: This class and its members cannot be used in applications that execute in the Windows Runtime.

bob1697225-Jun-12 9:02

bob16972

25-Jun-12 9:02

Albert Holguin wrote:
There was an article about this not too long ago stating the intent for Visual
Studio to keep supporting desktop application development, which means it will
keep getting supported in Windows

I had seen something about that but it almost sounded like it was discussing running it on and targeting some previous versions of Windows. That apparently confused me enough to cause some concern.

thanks for reponding.

Re: This class and its members cannot be used in applications that execute in the Windows Runtime.

Albert Holguin25-Jun-12 12:38

Albert Holguin

25-Jun-12 12:38

Sure, no problem. I've kept an eye out for this as well since I work on desktop applications. I doubt they'll completely get rid of the traditional desktop support any time soon, if so, I'm sure Linux will have a ton of users flocking in their direction. The market for traditional desktop applications is still large for the engineering/scientific community.

error C2660 :,, opencv with mfc (Solved)

jawadali47724-Jun-12 19:34

jawadali477

24-Jun-12 19:34

hi,
i'm developing dialog based GUI code for my project using opencv with mfc. i'm getting following error for the MouseCallback function which i don't understand why

error C2660: 'SetDlgItemTextW' : function does not take 2 arguments

following is the code that causes this error

void leftclick( int event, int x, int y, int flags, void* param )
{
	if( event == CV_EVENT_LBUTTONDBLCLK )
	{
		CvScalar s; 
		CString Blue, Green, Red;
		zoomed = (IplImage*) param;

		s=cvGet2D(zoomed,x,y);		// get the (x,y) pixel value 
		Blue.Format(_T("%0.2f"), s.val[0]);
		Green.Format(_T("%0.2f"), s.val[1]);
		Red.Format(_T("%0.2f"), s.val[2]);
		SetDlgItemText(IDC_Blue, Blue);   /error C2660
		SetDlgItemText(IDC_Green, Green);   /error C2660
		SetDlgItemText(IDC_Red, Red);   //error C2660
	}
}

this mouse event is being called in a thread as

cvSetMouseCallback( "box.png", &leftclick, 0 );

any idea what i'm missing. do i have to define the mouse event in the dialog class??

Regards
Jawad

modified 25-Jun-12 6:42am.

Re: error C2660 :,, opencv with mfc

«_Superman_»24-Jun-12 19:47

«_Superman_»

24-Jun-12 19:47

You need to pass in the dialog handle as the first parameter to SetDlgItemText function because it is not being called from inside a CWnd derived class. So the SetDlgItemText function that you're calling is actually the Windows API - http://msdn.microsoft.com/en-us/library/windows/desktop/ms645521(v=vs.85).aspx[^]

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Polymorphism in C

Re: error C2660 :,, opencv with mfc

SoMad24-Jun-12 19:53

SoMad

24-Jun-12 19:53

Since you are calling this from a thread and not from inside the dialog class, you have to pass the hWnd of the dialog as the first parameter to SetDlgItemText()[^].

You should know that doing this from another thread is a risky way.

Soren Madsen

Re: error C2660 :,, opencv with mfc

fat_boy24-Jun-12 21:54

fat_boy

24-Jun-12 21:54

You need to send the handle of the dialog to the thread because all thes window funcs come in two forms:

The global:

::SetDlgItemText(HWND, IDC_Blue, Blue);

And the Class Specific:

myDlgItem->SetDlgItemText(IDC_Blue, Blue); or
this->SetDlgItemText(IDC_Blue, Blue);

'this' is of course given for free if you are inside the actually controls class so you can write:

SetDlgItemText(IDC_Blue, Blue);

So, you are in a thread, NOT in the MFC class instance, so you need to pass the window handle to the thread in order to manipulate it there.

Or even better create your own messaging system so you can send a message to the main window thread from your thread so the main window thread can do all the detailed work rathert than having to code it in your worker thread.

Re: error C2660 :,, opencv with mfc

jawadali47725-Jun-12 0:40

jawadali477

25-Jun-12 0:40

thank you everyone..that was really helpful.
thanks again. Smile | :)

Dynamic cast question

ForNow24-Jun-12 18:45

ForNow

24-Jun-12 18:45

Hi,

SockCleintThread is a derived class from base Class CWinThread

so <pre lang='cpp'> CWinThread* current;
dynamic_cast<SockCLeintThread*>(current)= AfxGetThread(); </pre>

in fact the compiler is telling me to do what I am doing

why is it flagging the statement as a error

SockCLient.cpp(12) : error C2440: '=' : cannot convert from 'CWinThread *' to 'SockCLeintThread *'
1> Cast from base to derived requires dynamic_cast or static_cast

Re: Dynamic cast question

«_Superman_»24-Jun-12 19:51

«_Superman_»

24-Jun-12 19:51

I guess the cast should be like this -

SockCLeintThread* current = dynamic_cast<SockCLeintThread*>(AfxGetThread());

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Polymorphism in C

Re: Dynamic cast question

Richard MacCutchan24-Jun-12 22:29

Richard MacCutchan

24-Jun-12 22:29

I don't think you can cast the LHS of an expression. It should be:

C++

SockCLeintThread* current = dynamic_cast<SockCLeintThread*>(AfxGetThread());

AfxGetThread() returns a CWinThread* by default, so you need to cast that to the actual type that will be returned when storing it in your thread pointer. If you define current as a CWinThread* then you will not be able to use it as a SockCLeintThread* anywhere following.

speaking as ...

Re: Dynamic cast question

fat_boy25-Jun-12 0:45

fat_boy

25-Jun-12 0:45

CWinThread* current = (CWinThread*)AfxGetThread();

That's the simplest coding, using the C cast. But see what you are doing? You are casting AfxGetThread() to a CWinThread type.

So in C++:

CWinThread* current = dynamic_cast<cwinthread*>AfxGetThread();

SetDIBits and GetDIBits (Aarot.zip)

Rabindra Laheri24-Jun-12 18:33

Rabindra Laheri

24-Jun-12 18:33

Hi I have downloaded aarot.zip and trying to understand the code. Bcoz i need to implement that on embedded programming.
But the API used here is not known to me.
So can anyone help me to understand the code.

AND IF POSSIBLE
Plz help me to know source code of the functions SetDIBits and GetDIBits. How it is working.

Thanks

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