C / C++ / MFC

Re: What does this syntax mean?

28-Feb-06 12:07

It specifies how many bits are used to store the variable. In this case it is one bit. Look up "bit fields" in MSDN or see http://www.codeproject.com/cpp/bitbashing.asp[^]

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Ryan Binns28-Feb-06 18:18

Ryan Binns

28-Feb-06 18:18

As the others have said, it says that that field takes up one bit.

However, don't be tempted to use bit fields in your own structures. They are highly non-portable, even when compiling for the same platform. Different Windows compilers may treat them in different ways. Even different versions of the same compiler on the same platform can treat them differently. Use them only if you can guarantee that you will only ever compile your code with the same compiler (same version, same vendor etc...). The problem is that the C standard does not specify in which order the fields are to appear in memory - compilers are free to do whatever they like.

Ryan

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Any java/C#-like STL alternatives for unmanaged c++?

FocusedWolf28-Feb-06 11:03

FocusedWolf

28-Feb-06 11:03

Just wondering because...some things...strings, iterators, lists, etc are nice and clean in java and c#, but are ugly or lacking in c++.

Over time i see code project articles try to bring some of that c# goodness to c++, like with delegates, foreach, and properties...so is their any library out there that does this in a big way...make c++ like C# with memory leaks i mean :P

Re: Any java/C#-like STL alternatives for unmanaged c++?

C^hris L^osinger28-Feb-06 12:06

C^hris L^osinger

28-Feb-06 12:06

see: STL, Boost, etc

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Re: Any java/C#-like STL alternatives for unmanaged c++?

Stephen Hewitt28-Feb-06 12:36

Stephen Hewitt

28-Feb-06 12:36

If you've looked at Boost you'd be asking the opposite question. For example the multi index containers and the Boost graph library are unbelivable and only available in C++. Some of what you mention has been available (in the STL) for years, in fact before dotNET even existed - std::string and iterators for example.

Steve

Reading a 16bit data file???

pavanbabut28-Feb-06 10:18

pavanbabut

28-Feb-06 10:18

Hi,
I am having a 16bit ascii file which contains signed integers from -8191 to +8191. These integers are stored in a file in a single row without any delimiters. Can anyone gimme a sample code which can read this kind of file for the signed integers (b/n -8191 and +8191) stored in it or do I need any more info to perform this?
thanks,
-Pav.

David Crow28-Feb-06 10:27

28-Feb-06 10:27

So are you wanting to read the file two bytes at a time? If so, just use a short. To see if you are on the right track, try:

FILE *pFile = fopen("", "rb");
short num1, num2, num3;
fread(&num1, sizeof(short), 1, pFile);
fread(&num2, sizeof(short), 1, pFile);
fread(&num3, sizeof(short), 1, pFile);
fclose(pFile);

Now if num1, num2, and num3 are correct, you're on your way.

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PJ Arends28-Feb-06 11:08

28-Feb-06 11:08

What do you mean by "16 bit ascii"? Do you mean a UNICODE text file? or do you mean that the numbers are stored in a 16 bit binary format (every 16 bits or two bytes is another number)?

How the the numbers are stored in the file will determine how you have to read it.

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pavanbabut28-Feb-06 11:21

pavanbabut

28-Feb-06 11:21

It's a 16 bit binary format. The numbers are stored one after the other without any delimiters.
thanks,
-Pav

PJ Arends28-Feb-06 11:47

C++ app with no MS CRT usage

28-Feb-06 11:47

So the file is a series of shorts. Simply open the file and read in one short at a time.

You may be right
I may be crazy
But it just may be a lunatic you’re looking for
-- Billy Joel --

Within you lies the power for good - Use it!

Jim Crafton28-Feb-06 10:00

Jim Crafton

28-Feb-06 10:00

Has anyone built a C++ app that uses the STL but does NOT use the CRT? Is this possible?

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Re: C++ app with no MS CRT usage

PJ Arends28-Feb-06 11:12

Re: C++ app with no MS CRT usage

28-Feb-06 11:12

Not possible, STL uses the CRT.

You may be right
I may be crazy
But it just may be a lunatic you’re looking for
-- Billy Joel --

Within you lies the power for good - Use it!

James Brown28-Feb-06 13:00

James Brown

28-Feb-06 13:00

I was thinking that in some ways, STL is the CRT so the two cannot really be separated...but here's a thought:

If you define the STL to be just a collection of header-files, and the CRT to be things like new[], delete[] etc

Then it would be possible to write your own implementation of global new[], delete[], plus provide a few other necessary house-keeping routines like mainCRTStartup. Add the compiler option to strip the CRT, and maybe one could cobble something together which, when linked to your 'custom' CRT, could be twisted enough to meet the original requirement...

can't imagine why anyone would want to do this..

james

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Re: C++ app with no MS CRT usage

derek728-Feb-06 15:17

derek7

28-Feb-06 15:17

I have oppsite question. it should have more sense.

if you do not use stl stuff ,how to unlinke stl lib from my project?

it seem stl is default linked to any c++ project(I use vc)

debugging an exe on windows xp

ns28-Feb-06 8:20

28-Feb-06 8:20

What can be used on windows xp to debug an application at runtime? I cant step through it because its an exe thats launched by another exe, and it calls some dlls, which might be where the problem is occuring,
thanks,
sb

SDI's View DC

masnu28-Feb-06 6:54

28-Feb-06 6:54

Is there a way of sending my class a pointer to my view's DC. I would like to draw to the DC and then "blit" it back to the screen. Until now I have only been able to get the DC for the main window.

Thanks.

PJ Arends28-Feb-06 7:40

28-Feb-06 7:40

CFrameWnd::GetActiveView will return a pointer to your CView derived window, you can call GetDC on that view

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I may be crazy
But it just may be a lunatic you’re looking for
-- Billy Joel --

Within you lies the power for good - Use it!

masnu28-Feb-06 7:59

28-Feb-06 7:59

I tried what you suggested and I get an "illegal call of non-static member function" error.

CView* pView = CFrameWnd::GetActiveView();<br />
CDC* pDC = myview->GetDC();

I am new to the whole MFC programming scene so I am sure I am doing something really silly.

Thanks for the help.

-- modified at 14:00 Tuesday 28th February, 2006

David Crow28-Feb-06 8:12

28-Feb-06 8:12

masnu wrote:
CView* pView = CFrameWnd::GetActiveView();

GetActiveView() is not a static function (i.e., one that can be called without an actual object). You must call it in the context of a CFrameWnd object, not CFrameWnd itself.

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"There is no death, only a change of worlds." - Native American Proverb

masnu28-Feb-06 8:52

28-Feb-06 8:52

David,

From what you said I assume I need to put the code in my CMainFrame class, which I did. I no longer get a compiler error, but I get an access violation error in the objcore.cpp file:

BOOL CObject::IsKindOf(const CRuntimeClass* pClass) const<br />
{<br />
	ENSURE(this != NULL);<br />
	// it better be in valid memory, at least for CObject size<br />
	ASSERT(AfxIsValidAddress(this, sizeof(CObject)));<br />
<br />
	// simple SI case<br />
	CRuntimeClass* pClassThis = GetRuntimeClass();   //ERROR HERE<br />
<br />
	ENSURE(pClassThis);<br />
	return pClassThis->IsDerivedFrom(pClass);<br />
}

What I have is:

void CMainFrame::Scroll()<br />
{<br />
	CDC* pDC = CFrameWnd::GetActiveView()->GetDC();<br />
<br />
	CStripChart* pStrip;<br />
	pStrip->Scroll(pDC);<br />
}

Any suggestions?

Thanks.

David Crow28-Feb-06 9:05

28-Feb-06 9:05

masnu wrote:
CStripChart* pStrip;
pStrip->Scroll(pDC);

This looks suspect. How has pStrip been initialized?

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

masnu28-Feb-06 9:37

28-Feb-06 9:37

When I debug, that code doesn't even run. The problem occurs when

CDC* pDC = CFrameWnd::GetActiveView()->GetDC();

is executed.

CStripChart is just a class I created to accept a DC and draw a grid to it and plot what ever data is sent to it. I have scroll function as a seperate thread. Could this be a problem?

Is there any way I can get a pointer to the view's DC and pass it to my class for furture use? Or would I need to pass a new DC everytime I wanted to update my window?

David Crow28-Feb-06 10:01

28-Feb-06 10:01

What does GetActiveView() return? If it is NULL, then dereferencing the pointer will cause problems.

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

masnu28-Feb-06 10:34