C / C++ / MFC

MSVC++ 8 SP1: delete const pointer [modified]

12-Feb-07 17:35

For show text you can use of SetWindowText with CStatic control or use of a CEdit

WhiteSky

N-O-R-B-E-R-T12-Feb-07 9:29

N-O-R-B-E-R-T

12-Feb-07 9:29

After some sloppy refactoring I found something like this in my code:

<br />
class FooBar;<br />
<br />
void foo(const FooBar* const pBar)<br />
{<br />
    //do something<br />
    //...<br />
<br />
    delete pBar;<br />
} <br />

So far, so bad. What surprised me, was the fact that this code compiled without any error or warning. I was told, that this compiles also in GCC.

This also compiles though a non-const member function is called:

<br />
void foo(const FooBar* const pBar)<br />
{<br />
    pBar->~FooBar();<br />
} <br />

Can you tell me why these snippets work (or at least compile)?

thanks,
Norbert

David Crow12-Feb-07 9:45

David Crow

12-Feb-07 9:45

You're not changing pBar or what it points to, are you?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

CPallini12-Feb-07 9:58

CPallini

12-Feb-07 9:58

I'm surprised too about that behavior: technically the method doesn't change neither the pointer value nor the object itself, but substantially it makes a big change to both. I think it may be a good candidate to subtle bugs.

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.

Mark Salsbery12-Feb-07 10:37

12-Feb-07 10:37

Of possible interest: Error message in Visual C++ when you delete a pointer to a const object[^]

"NOTE: Visual C++ .NET compiler does not demonstrate this issue in conformance to the changes
made in the C++ ANSI Standards."

I wonder what the change is...

deleting through a const pointer[^]

Parse data from dialog form editctrl to excel sheet cell?

N-O-R-B-E-R-T12-Feb-07 14:23

N-O-R-B-E-R-T

12-Feb-07 14:23

Thanks for your replies and especially for the links.

Norbert

rolfhorror12-Feb-07 8:32

rolfhorror

12-Feb-07 8:32

Is it possible to parse/send input data from a dialog form editctrl to an existing excel sheet/form (xls) cell?
Maybe this can be done through storing the formdata like in an csv-file or something that later can be imported to the right cells and rows in an excel (xls) sheet?
I've searched the net for solutions, but it seems like this is hard to do.. but it must be possible in some way. (VC++ 6.0)

anyone?

Re: Parse data from dialog form editctrl to excel sheet cell?

David Crow12-Feb-07 9:17

David Crow

12-Feb-07 9:17

Yes, you can do this quite easly using Excel Automation.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Change dialog bkgrnd color in .NET

JBAK_CP12-Feb-07 8:27

12-Feb-07 8:27

I am aware of how to change the background color of the entire dialog in VS 6.0 (SetDialogBkColor(RGB(192,202,202) in InitInstance), but this does not seem to work in a dialog based project created in .NET

Any help on how to accomplish this in .NET would be apperciated.
Thanks!

toxcct12-Feb-07 8:32

12-Feb-07 8:32

overload OnEraseBkground()

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JBAK_CP12-Feb-07 8:37

12-Feb-07 8:37

do I just do a 'SetDialogBkColor(RGB(192,202,202),RGB(0,0,0))' inside 'OnEraseBkgnd'?

Mark Salsbery12-Feb-07 9:06

12-Feb-07 9:06

You can set the background brush in the window class or handle WM_ERASEBKGND. For the latter,
you need to draw the background yourself, using whatever method you want.

SetDialogBkColor is an obsolete method.

JBAK_CP12-Feb-07 9:17

12-Feb-07 9:17

Ok, I handle the OnEraseBkgnd(CDC* pDC) and put the following in there:

CRect Rect;
GetClientRect(&Rect);
CBrush Bursh(RGB(192,202,202));
pDC->FillRect(&Rect,&Bursh);
return TRUE;

This seems to change the background, but my static text and edit boxes are still grey? Am I missing something?
Thanks

toxcct12-Feb-07 9:25

12-Feb-07 9:25

if you want the static controls backgrounds to be transparent, overload WM_CTLCOLOR. here a cool effect :

HBRUSH CMyDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) {
    HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
    if (nCtlColor == CTLCOLOR_STATIC) {
        pDC->SetBkMode(TRANSPARENT);
        pDC->SetTextColor(RGB(192, 192, 192));
        hbr = static_cast<HBRUSH>(GetStockObject(NULL_BRUSH));
    }
    return hbr;
}

BOOL CMyDlg::OnEraseBkgnd(CDC* pDC) {
    CRect rect;
    GetClientRect(&rect);
 
    COLORREF c1 = RGB(64, 0, 64);
    COLORREF c2 = RGB(0, 128, 128);
 
    for(int i = 0; i < rect.Height(); i++) { 
        int r, g, b;
        r = GetRValue(c1) + (GetRValue(c2) - GetRValue(c1)) * i / rect.Height();
        g = GetGValue(c1) + (GetGValue(c2) - GetGValue(c1)) * i / rect.Height();
        b = GetBValue(c1) + (GetBValue(c2) - GetBValue(c1)) * i / rect.Height();
        pDC->FillSolidRect(0, i, rect.Width(), 1, RGB(r, g, b));
    }
 
    return TRUE;
}

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JBAK_CP12-Feb-07 10:18

12-Feb-07 10:18

Thanks all for the help, it worked
toxcct, thanks for the cool sample Smile | :)

Mark Salsbery12-Feb-07 10:45

Re: Change dialog bkgrnd color in .NET [modified]

12-Feb-07 10:45

I like your OnEraseBkgnd() implementation!

It has now become the background to my little MFCTester project I keep around for testing code
before I post it here.

I hope there's no royalties Smile | :)

Mark

toxcct12-Feb-07 10:47

12-Feb-07 10:47

hehe, :-> i know some would have liked it...

enjoy, it's perfectly free Cool | :cool:

BTW, i borrowed the shading effect to Nish on his personal blog

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Mark Salsbery12-Feb-07 10:23

12-Feb-07 10:23

arunkk1 wrote:
but my static text and edit boxes are still grey? Am I missing something?

Yes.

To extend toxcct's reply for the edit boxes

HBRUSH CMyDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
    HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
 
    if (nCtlColor == CTLCOLOR_STATIC)
    {
        pDC->SetBkMode(TRANSPARENT);
        pDC->SetTextColor(RGB(192, 192, 192));
        hbr = static_cast(GetStockObject(NULL_BRUSH));
    }
    else if (nCtlColor == CTLCOLOR_EDIT)
    {
        pDC->SetTextColor(RGB(...,...,...));
        pDC->SetBkColor(RGB(...,...,...));
        hbr = (...some brush...);
    }
 
    return hbr;
}

Hamid_RT12-Feb-07 17:35

12-Feb-07 17:35

You can use of WM_ERASEBKGND or WM_CTLCOLOR

WhiteSky

toxcct12-Feb-07 20:22

12-Feb-07 20:22

dear you have to tell me...

Why on earth do you keep posting something that has already been suggested way better many hours after ?! Frown | :(

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Hamid_RT12-Feb-07 20:27

12-Feb-07 20:27

On the earth Sigh | :sigh:

WhiteSky

toxcct12-Feb-07 20:30

12-Feb-07 20:30

you are gold medal man, you quite have ne excuse.

and wht can't you explain yourself ?
i know english is far from being your mother tongue, but please try and use simple words and short sentences, so that we can understand together...

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Hamid_RT12-Feb-07 20:46

12-Feb-07 20:46

Well I can read english but for write not very well and you said explain yourself but what ?

WhiteSky

toxcct12-Feb-07 20:53