C / C++ / MFC

How to use this template with varying sizes? [modified]

31-Oct-07 10:43

In addition to Judy's excellent reply....

A sockaddr is a generic structure since sockets can be used on
any protocol, not just IP protocols.

Therefore, for IP(4) protocols, a sockaddr_in (socket address internet) structure is used
since it specifically defines a complete IP address.

You can also bind to the address INADDR_ANY if you want to let WinSock pick the adapter
to bind to:

localAddress.sin_addr.s_addr = INADDR_ANY;

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Usage of bind()

JudyL_MD1-Nov-07 2:50

JudyL_MD

1-Nov-07 2:50

Mark Salsbery wrote:
In addition to Judy's excellent reply....

Devinder31-Oct-07 9:44

Devinder

31-Oct-07 9:44

I have added <> to the code. My compare function works. I want to ask how to set up the input parameters for compare functions, so that Compare works on 2 different sizes.
-- modified at 12:32 Thursday 1st November, 2007

The following is small sample of the template code I am using.

template <unsigned char sz> class MyStringBase<br />
{<br />
	protected:<br />
		unsigned char Len;<br />
		char Data[sz];<br />
};<br />
<br />
template <unsigned char sz> class MyString : MyStringBase<sz><br />
{<br />
	public:<br />
		MyString () { Len = 0; Data[Len] = 0}<br />
		MyString (const char* src);<br />
		bool Compare(MyString??? rhs, int len);<br />
};<br />
<br />
template<unsigned char sz> MyString <sz>::MyString (const char* src)<br />
{<br />
   long len = strlen(src);<br />
   Len = (unsigned char)((len > sz)? sz: len);<br />
   strncpy(Data, src, Len);<br />
}<br />
<br />
template<unsigned char sz> bool MyString <sz>::Compare(MyString??? rhs, int len)<br />
{<br />
	if (len<0)<br />
		len = Len;<br />
	return ((Len==rhs.Len) && (Len<=len) && (strncmp(Data,rhs.Data,len)==0));<br />
}

Compare function has MyString??? which I need to get filled in so I can do the following

MyString<40> a("Test String 1");<br />
MyString<80> b("Testing of String 2 is good") ;<br />
<br />
bool same4 = a.Compare(b,4);

Thank you for your response.

Re: How to use this template with varying sizes?

Stephen Hewitt31-Oct-07 19:45

Stephen Hewitt

31-Oct-07 19:45

Please edit your post so that all "<" and ">" symbols and their contents are visible.

Steve

Re: How to use this template with varying sizes?

John R. Shaw31-Oct-07 23:48

John R. Shaw

31-Oct-07 23:48

I would like to say that I might experiment with that, but I would be lying. Your best bet is to use the strings provided by the STL.

Given that and the fact that you are mixing C++ and C (normal - actually), then internally to your class, use ‘strncmp’ to compare a particular number of characters.

Look if you understand basic programming, then you can write 70% of the C library in a week, including non-standard methods.

int compare(char* s, size_t n)
{
   int i;
   for( i=0; s[i]; ++i )
      if( Data[i] != s[i] )
         return(Data[i] - s[i]);
   return(0);
}

Or something like that.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: How to use this template with varying sizes?

Stephen Hewitt1-Nov-07 17:50

Stephen Hewitt

1-Nov-07 17:50

template <unsigned char sz> class MyString : MyStringBase<sz>
{
public:
MyString () { Len = 0; Data[Len] = 0}
MyString (const char* src);
template <unsigned char sz>
bool Compare(const MyString<sz2> &rhs, int len);
};
 
template <unsigned char sz>
template <unsigned char sz2>
inline bool MyString<sz>::Compare(const MyString<sz2> &rhs, int len)
{
if (len<0)
len = Len;
return ((Len==rhs.Len) && (Len<=len) && (strncmp(Data,rhs.Data,len)==0));
}

I think VC6 will have trouble with this code and you'll need to move the definition of Compare into the class (in which case drop the bits in italic).

Steve

OnPrint with MFC

mnnca31-Oct-07 7:08

31-Oct-07 7:08

Does anyone know why the Print function works in DEBUG mode, but not in RELEASE mode (it is blank)? (Visiual C++ 6.0).

Thanks.

mnnca

Gofur Halmurat31-Oct-07 7:10

Gofur Halmurat

31-Oct-07 7:10

what is the difference between debug mode and release mode?

mnnca31-Oct-07 7:29

31-Oct-07 7:29

When I compile it (single document MFC app) in debug mode, the document has the right data (on the view and printer).
When I compile it in release mode, the document is always blank.

mnnca

Mark Salsbery31-Oct-07 7:16

31-Oct-07 7:16

What Print function? What "is blank"?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

mnnca31-Oct-07 7:34

31-Oct-07 7:34

I use standard code from MFC examples:
void CDISKVERView::OnPrepareDC(CDC* pDC, CPrintInfo* pInfo)
{
CDISKVERDoc* pDoc = GetDocument();
CScrollView::OnPrepareDC(pDC, pInfo);
pDC->SetMapMode(MM_ANISOTROPIC);
CSize sizeDoc = pDoc->GetDocSize();
sizeDoc.cy = -sizeDoc.cy;
pDC->SetWindowExt(sizeDoc);
CSize sizeNum, sizeDenom;
sizeNum.cx=1;
sizeNum.cy=1;
sizeDenom.cx=1;
sizeDenom.cy=1;
//debug mode works ok
//release mode doesnt work !!dont know why
// GetZoomFactor(&sizeNum, &sizeDenom); this is not a valid function, why?
int xLogPixPerInch = pDC->GetDeviceCaps(LOGPIXELSX);
int yLogPixPerInch = pDC->GetDeviceCaps(LOGPIXELSY);
long xExt = (long)sizeDoc.cx * xLogPixPerInch * sizeNum.cx;
xExt /= 100 * (long)sizeDenom.cx;
long yExt = (long)sizeDoc.cy * yLogPixPerInch * sizeNum.cy;
yExt /= 100 * (long)sizeDenom.cy;
pDC->SetViewportExt((int)xExt, (int)-yExt);
}
The Print function:
pDC->TextOut(x,y, String1);

When I compile it in debug mode, the output/document is ok.
when I compile it in release mode, the output is a blank page.

Thanks.
Mandy

mnnca

Mark Salsbery31-Oct-07 8:37

31-Oct-07 8:37

Hmm...besides rendering to coordinates that don't map to a visible
area of the page, I can't see what would cause the page to be blank.

You could try adding debug info to your release build project
C++ and linker settings and step throu in the debugger and see if
maybe there's an improperly used ASSERT() macro somewhere or
check values in your printing code to see if you're getting what you
expect.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

mnnca31-Oct-07 11:06

31-Oct-07 11:06

Hi:
Thanks for the tips.
I inserted lots of debug statements (in release mode) to display the cordinates (x,y), they look ok (within page boundary).
There are differences between the debug and release libraries (MSVCRTD.dll, MFC42D.dll, MFCO42D.dll).
One difference I found is the height of the TEXTMETRIC. I even tried to set it to a fixed value (17, as seen in debug mode), it still doesnt work.

mnnca

mnnca

Mark Salsbery1-Nov-07 5:32

1-Nov-07 5:32

That's a tough one.

It looks like all your y coordinates (when drawing) should be negative
to be visible. Is that the case?

You can try using a window DC instead of a printer DC (like print-preview).
Saves time debugging and maybe you'll see something that you're not seeing
on the printed pages.

You may want to go through the project settings and compare ALL
settings between the release and debug. Make sure there's not a
release setting that would obviously change behavior.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

mnnca2-Nov-07 10:16

2-Nov-07 10:16

I don't know how to use the "window DC" suggested by you.
The blank page is both on preview (monitor display) and on printer output.
Thanks.

mnnca

mnnca7-Nov-07 7:58

7-Nov-07 7:58

I've just tried something else: I use different code (from an old proj) and it works ok now in both debug and release mode.
In a previous post, the OnPrepareDC is from a MFC sample.

void CDISKVERView::OnPrepareDC(CDC* pDC, CPrintInfo* pInfo)
{
CFormView::OnPrepareDC(pDC, pInfo);

CClientDC dcScreen(NULL); //Get the display's device context
pDC->SetMapMode(MM_ANISOTROPIC); //Map aspect ratio
// map 1 screen logical inch to 1 printer (/output) logical inch
pDC->SetWindowExt(dcScreen.GetDeviceCaps(LOGPIXELSX),
dcScreen.GetDeviceCaps(LOGPIXELSY)); //Window is display
pDC->SetViewportExt((2*pDC->GetDeviceCaps(LOGPIXELSX)),
(2*pDC->GetDeviceCaps(LOGPIXELSY))); //Viewport is printer

}

mnnca

Mark Salsbery7-Nov-07 9:45

7-Nov-07 9:45

mnnca wrote:
// map 1 screen logical inch to 1 printer (/output) logical inch

Aren't you mapping 1 screen logical inch to 2 printer logical inches?

I'm still not sure why the other one worked in one build mode and not the other...

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

mnnca7-Nov-07 10:54

7-Nov-07 10:54

The comment didnt match the code, however, when I tried 1 to 1 mapping, it works the same (I dont really know why).
When it works with the old code, I was so relieved that I didnt investigate more into the problem.
After reading your post, I went back and traced all the code and found out why it didnt work (in release mode only):
the only code which was missing is the SetMapMode in the OnPrint(...)which made it not work:
void CDISKVERView::OnPrint(CDC* pDC, CPrintInfo* pInfo /*pInfo*/)
{
pDC->SetMapMode(MM_LOENGLISH);
CDISKVERView::PrintPage( pDC, pInfo);
}
when I add that line in the old prj file, it works. I dont understand why though.

mnnca

Mark Salsbery7-Nov-07 11:04

7-Nov-07 11:04

mnnca wrote:
when I add that line in the old prj file, it works. I dont understand why though.

That's a good sign that OnPrepareDC() wasn't setting up the DC the way the code
doing the printing ( CDISKVERView::PrintPage()) was expecting. That's certainly a
different map mode than OnPrepareDC() is using Smile | :)

So did you get it all working the way you wanted??

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

mnnca7-Nov-07 11:13