C / C++ / MFC

Re: Necessity of the const keyword?

5-Oct-01 19:12

It's funny, I only recently have started to think more about 'const' and the fact that well written code will use it. Given that it never makes something work to declare it const, it's just something I knew about but didn't consider overmuch. I guess that's because I've taught myself to program, in the same way that the need to preserve namespaces rather than declare using on an entire namespcae is something I came to grips with by discussing it here.

I have nothing intelligent to add to what Michael has said ( no surprises there ), I just wanted to say as someone who constantly seeks to better himself and learn to do things *well*, and a veteran of many fights over STL before my workmates accepted it over MFC containers and ones they had written, all I can say is 'stick to your guns'. Get a copy of Stroustrup if you don't have one and quote it like the Bible. There is no way any remotely competent developer can argue with the guy who wrote the language without bringing some hefty evidence to the table.

Everyone at work uses STL now, to the point where I find it in the code instead of being called over to help impliment/optimise it. I'm sure you'll win your battle to, because you are right. Anyone who thinks it is a 'waste of time' to do things properly is a monkey.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Tomasz Sowinski6-Oct-01 1:46

Tomasz Sowinski

6-Oct-01 1:46

Const is at its best when enforcing compile-time safety. There are some myths about possible optimizations, you can read more at http://www.gotw.ca/gotw/081.htm

Tomasz Sowinski -- http://www.shooltz.com

SW_HIDE

RobJones5-Oct-01 12:23

RobJones

5-Oct-01 12:23

How can you tell if a window is SW_HIDE or SW_MINIMIZE.. I want to do a function, but if the window is hidden or minimized, I dont want the function to run.

Thanks,

Rob

Fazlul Kabir5-Oct-01 12:27

5-Oct-01 12:27

Call ::GetWindowPlacement(..)

WINDOWPLACEMENT wp;
GetWindowPlacement(&wp);
if(wp.flags == SW_SHOWMINIMIZED)
{
// window is minimized
}

Hope this helps.

// Fazlul

Get RadVC today! Play RAD in VC++
http://www.capitolsoft.com

RobJones5-Oct-01 13:09

RobJones

5-Oct-01 13:09

I implemented this:

void CTimerDlg::RefreshTimer()
{
	UpdateData(TRUE);
	
	WINDOWPLACEMENT wp;
	CTimerDlg::GetWindowPlacement(&wp);
	if(&wp.flags == SW_HIDE)
	{
		//Do not show the Refresh Dialog Box and dont refresh the timer
	}
	else
	{
		OnBstop();//stop the timer
		
		//Display the Refresh Dialog Box
		if (!::IsWindow(m_dRefreshDlg.GetSafeHwnd()))
	       m_dRefreshDlg.Create(IDD_REFRESH, this);
	
	    m_dRefreshDlg.ShowWindow(SW_SHOW);
			
		OnBstart();// restart the timer
	
		m_dRefreshDlg.ShowWindow(SW_HIDE);
	}
}

When my timer reaches 1 hour I have it do the RefreshTimer() function.. I have a dialog pop-up unitl the OnBstop() and OnBstart functions complete.. I only want the dialog box to open if the program is not hidden.. this works fine but after this function runs.. it locks up the program.. any ideas

Rob

Fazlul Kabir6-Oct-01 19:21

6-Oct-01 19:21

Hey Rob:

Sorry for the late reply. Hope the problem has already been fixed.

I tried to reproduce the problem on my end, but it seemed to work fine. If you still have the problem, can you please email me a test app? Just thought I might be missing something..

// Fazlul
fkabir@capitolsoft.com

Get RadVC today! Play RAD in VC++
http://www.capitolsoft.com

RobJones8-Oct-01 4:08

RobJones

8-Oct-01 4:08

Thanks, every thing is working fine now.. I have a Multimedia Timer in my app, I have a event fire at a certian time and i dont want the event to be visible if the window is hidden.. I moved the function to the WM_TIMER instead of the Multimedia timer, everything seems to be working fine.. Thanks for the help.

Rob

Stan Shannon5-Oct-01 12:34

Stan Shannon

5-Oct-01 12:34

There is also an IsIconic call which will tell you if its minimized I believe.

"I never met anyone I didn't like" Will Rogers.

Fazlul Kabir6-Oct-01 18:55

6-Oct-01 18:55

Just thought I should add this...
As you said, ::IsIconic() will tell if the window is in minimized/iconic state, even though the window may still be in visible state (i.e. not hidden).

// Fazlul

Get RadVC today! Play RAD in VC++
http://www.capitolsoft.com

Multiple Splitters in WTL

Michael Dunn5-Oct-01 14:51

Michael Dunn

5-Oct-01 14:51

IsWindowVisible() to tell if a window is hidden.
IsZoomed() to tell if a window is maximized.

--Mike--
http://home.inreach.com/mdunn/
"Listen you footwarriors, can you hold down a bit with the firing? I've just got three impromptu weddings breaking out behind me!" -- Arthur Dent
Heart | [heart]

your

with

and

Scrolling a CListBox.

John Uhlenbrock5-Oct-01 12:02

John Uhlenbrock

5-Oct-01 12:02

I am using SetTopIndex() to make sure the last string insterted can be seen. However, it scrolls really slow. For example, if I try adding something to the list box every 1/4 second, it adds one that often until it has to scroll. Then it slows down, closer to 1 every second. It has the same affect as internet explorer when you try to use the mouse wheel and scroll really fast, the window does not scroll fast and ends up jumpy.

@ny !d3@s?

- John

Leo Smith5-Oct-01 11:22

Leo Smith

5-Oct-01 11:22

I am trying to create an app in WTL that needs a tri-pane view. I create the splitters fine, but for some reason I can't get the splitter that is inside the splitter to layout properly. How would you call the update? The problem is that m_verSplit does not set the splitter over towards the middle. I have enclosed a sample of the code (removing things that don't necessarily pertain to the issue at hand). How does one address the top panes update function.

class CMainFrame : public CFrameWindowImpl<cmainframe>, public CUpdateUI<cmainframe>,
public CMessageFilter, public CIdleHandler
{
public:
DECLARE_FRAME_WND_CLASS(NULL, IDR_MAINFRAME)

CTestView m_view;
CTreeViewCtrl m_treeview;
CListBox m_listbox;
CHorSplitterWindow m_horSplit;
CSplitterWindow m_verSplit;

LRESULT OnCreate(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
HWND hTemp;

RECT rect = { 0, 0, 1, 1 };
m_hWndClient = m_horSplit.Create(m_hWnd, rect, NULL, WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN, 0);
hTemp = m_verSplit.Create(m_hWndClient, rect, NULL, WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN, 0);

UpdateLayout(); // need this for SetSplitterPos
m_horSplit.SetSplitterPos(250, FALSE);
m_verSplit.SetSplitterPos(250, FALSE);
m_view.Create(m_hWndClient);
m_treeview.Create(hTemp, rcDefault, NULL,
WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | TVS_HASLINES | TVS_LINESATROOT | TVS_HASBUTTONS, WS_EX_CLIENTEDGE);
m_listbox.Create(hTemp, rcDefault, NULL,
WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | LBS_NOINTEGRALHEIGHT, WS_EX_CLIENTEDGE);

m_horSplit.SetSplitterPanes(m_verSplit, m_view);
m_verSplit.SetSplitterPanes(m_listbox,m_treeview);

return 0;
}
};

Thanks,

Leo T. Smith
Senior Programmer/Analyst
Hartwick College

Has anybody programmed SNMP?

Kelly Herald5-Oct-01 10:57

Kelly Herald

5-Oct-01 10:57

I am trying to do a project here at work where I need to communicate to our Cisco Routers/switches to retrieve MAC addresses of the systems that are connected to them. I have the MIB file but I don't know how to connect to the switches using this file.

I can manually communicate with the switches using a program call GetIf but I need to be able to query the switches automatically. I have been looking in the MSDN about the WinSNMP APIs.

Any help is much appreciated. Any books that talk about how to program SNMP with code samples would be great too.

Thank you.

Kelly Herald
Micronpc, LLC

Re: Has anybody programmed SNMP?

Masaaki Onishi5-Oct-01 15:21

Masaaki Onishi

5-Oct-01 15:21

Hello, the codegurus around the world.;)

Basically, you need any SNMP library to talk with SNMP Agnet (Router) on MIB files.
HP has its own SNMP library for Windows and Unix, and you download somewhere.
However, this SNMP library for Windows is only for Windows, so we can find
the other SNMP library without Windows DLL.

I guess that MIB files is included into the hardware of the routers,
so we can't use the enterprise OID in this MIB files at all. Cry | :((

Good Luck!

Have a nice day!

-Masaaki Onishi-

How can I do a Dynamic Array like CByteArray for a STRUCT array ?

youssef5-Oct-01 10:23

youssef

5-Oct-01 10:23

Hi,

I create a STRUCT. My STRUCT is composed only by BYTE datas.
I would like to know how can I do for use this STRUCT in a CByteArray or other.
For example : CByteArray.RemoveAll; CByteArray.Add; ...

If anyone can help me.

Best Regards

youssef

youssef

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

Christian Graus5-Oct-01 10:59

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

5-Oct-01 10:59

USe STL vector, or List if you want to use InsertAt and RemoveAt ( called different things in STL ) a lot.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Paolo Messina5-Oct-01 11:01

Paolo Messina

5-Oct-01 11:01

You may use the template version of CArray to hold your structure.

#include <afxtempl.h>

CArray<MyStruct, MyStruct&> myarray;

The second typename is used for passing arguments of your type to memeber functions (usually a reference to the main type).
See MSDN for more info.

Paolo

------
"airplane is cool, but space shuttle is even better" (J. Kaczorowski)

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

Leo Smith5-Oct-01 11:05

Leo Smith

5-Oct-01 11:05

If I understand your question correctly, what I do is convert the struct into a class and have it inherit CObject as public. Once I do this, if I want the structure to be able to assign the values directly, I make all the values public. Then I make empty constuctor and destructor (unless you want to assign some default values). Then I will use CObArray. With this I can do everything I would do with CByteArray, but with typecasting:

CMyStruct *p = (CMyStruct *) m_array.GetAt(x);

If you wanted to do this cleaner (without the typecasting), you can create a new array class and have it do the typecasting for you, but I don't do this unless someone else will have to maintian the code.

class CMyStruct : public CObject
{
public:
int Val1;
int Val2;
CString Text1;

CMyStruct() {;}
~CMyStruct() {;}
};

I hope this helps.

Leo T. Smith
Senior Programmer/Analyst
Hartwick College

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

Fazlul Kabir5-Oct-01 11:27

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

5-Oct-01 11:27

I would use MFC's CPtrArray to store ptrs to your structs.

Thus, if you have two objects of a struct called MyStruct, like this:

MyStruct struct1, struct2;

You can declare a CPtrArray object and then add them like:

CPtrArray m_Array;
m_Array.Add(&struct1);
m_Array.Add(&struct2);

You can get the structs back later like:

MyStruct* pStruct1 = (MyStruct*)m_Array.GetAt(0);
MyStruct* pStruct2 = (MyStruct*)m_Array.GetAt(1);

Hope this helps.

// Fazlul

Get RadVC today! Play RAD in VC++
http://www.capitolsoft.com

Christian Graus5-Oct-01 16:53

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

5-Oct-01 16:53

CPtrArray takes void *, and you need to cast it yourself every time ? Oh.. the ugliness...

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Fazlul Kabir6-Oct-01 11:28

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

6-Oct-01 11:28

Actually, you don't need to typecast when you call CPtrArray::Add() method. However, you're right, you need to do that when you get the struct back using GetAt() method.

If typecasting bothers you too much, you can instead use MFC's template class CTypedPtrArray (declared in afxtempl.h). In this case, you don't need to typecast while calling GetAt() method. Here is how this works:

CTypedPtrArray < CPtrArray, MyStruct* > m_Array; 

m_Array.Add(&struct1);
m_Array.Add(&struct2);

// And to get the structs back later:

MyStruct* pStruct1 = m_Array.GetAt(0);
MyStruct* pStruct2 = m_Array.GetAt(1);

// Fazlul

Get RadVC today! Play RAD in VC++
http://www.capitolsoft.com

Christian Graus6-Oct-01 11:51

Re: How can I do a Dynamic Array like CByteArray for a STRUCT array ?

6-Oct-01 11:51

It doesn't *worry* me, it's just plain ugly IMHO. But I'm an STL zealot, so I'm likely to take a dim view of MFC containers, I guess....

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Fazlul Kabir6-Oct-01 18:06