C / C++ / MFC

Crop large file without temp file?

6-Mar-04 20:51

Well since the CDialog is derived from the CObject then it is well posible to serialize the object.

I believe you need to follow the guidlines how to make an implement serialization.

This space is empty.

pidhead6-Mar-04 19:26

pidhead

6-Mar-04 19:26

I need to remove the first ~1 MB or so from some files that tend to be 20 Gig or more.

Is there a way to do this without creating a complete copy of the file? My code currently seeks for the appropriate data in the front of the file, then coppies everything after that point to a new file.

If I could just "delete" the first part, I'd be set.

Any hints?

Neville Franks6-Mar-04 21:06

6-Mar-04 21:06

Can't see how this is possible. I think that the fastest way to copy a large file would be to use memory mapped files.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Prakash Nadar6-Mar-04 21:37

6-Mar-04 21:37

Neville Franks wrote:
I think that the fastest way to copy a large file would be to use memory mapped files.

Still it is going to consume 20gb of extra resource.

This space is empty.

Neville Franks6-Mar-04 22:19

6-Mar-04 22:19

Mr.Prakash wrote:
Still it is going to consume 20gb of extra resource.

Nope. You can simply move the remaining 19.9G in the orginal file. There is no need to copy the file in this particular case. A simple memmove() should do the trick.;)

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Prakash Nadar7-Mar-04 0:04

7-Mar-04 0:04

Neville Franks wrote:
Nope. You can simply move the remaining 19.9G in the orginal file. There is no need to copy the file in this particular case. A simple memmove() should do the trick.

Well in this case you need either 20gb of physical memory or 20gb of harddiskspace for the swapfile.

This space is empty.

Michael Dunn7-Mar-04 6:29

Michael Dunn

7-Mar-04 6:29

You'd need a new operating system too; Win32 only gives you 2GB of user process space. Wink | ;)

--Mike--
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Alexander ^M.,7-Mar-04 10:15

Alexander ^M.,

7-Mar-04 10:15

not true... there is an option to force the kernel(nt or later) to change it to 3gb user and 1gb kernel.

Don't try it, just do it! Wink | ;-)

Neville Franks7-Mar-04 11:50

7-Mar-04 11:50

With MMF you can spec the start offset and memory block size so you should be able to iterate through the file in say 20 x 1G segments. Certianly worth a try.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Ref Counting

monrobot136-Mar-04 18:52

monrobot13

6-Mar-04 18:52

I have a form with some edit boxes that do validation when they lose focus. I have an error variable (int) that keeps track of whether there was an error when the control lost focus. If there is an error it increases the ref count, and if there is no error it decreases the count. I'm having some trouble wrapping my head around how to work this logically. The system encounters several errors in keeping track. For example if I tab off the first edit and there is an error the count is increased to 1. If on the next box I enter a valid value and tab off the error count is decreased since there was no error. This has the effect of taking the ref count to 0 even though the first box still has an error. The only thing I've come up with so far is to have a boolean flag that is set when the ref is increased inside the function and if it wasn't then I shouldn't decrement it when it loses focus, but I don't really like that idea. Any ideas, links, or pushes in the right directions would be very appreciated. Here is some sample code of the KillFocus

if (VerifyCircuit ()) {
		// the circuit is valid decrease the error count unless it's already zero
		if (0 != m_nFieldError) { DelErrRef (); }
		// if there are no errors remove the error warning
		if (0 == m_nFieldError)
			GetDlgItem (IDC_ERROR)->ShowWindow (SW_HIDE);
		
		// remove the error string if it's there
		ErrorString (IDC_CIRCUIT_ERROR, FALSE);
	}
	else {
		// there is an error in the circuit, increase the error count
		AddErrRef ();

		// add the error string if not already there
		ErrorString (IDC_CIRCUIT_ERROR);
		// show the error warning
		GetDlgItem (IDC_ERROR)->ShowWindow (SW_SHOW);
	}

Sorry about the lenghty post.

- monrobot13

Re: Ref Counting

Neville Franks6-Mar-04 21:10

Passing information among different views

6-Mar-04 21:10

Why not validate the control when it looses focus and if there is an error use PostMessage() to put the focus back on the control and pop up a tooltip or balloon showing the error. Using MessageBox()'s to notify uses is far too in your face and requires user intervention.

Note that to get focus back to a control within KillFocus you can't use SetFocus() to SendMessage(). Hope that helps.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Re: Ref Counting

monrobot137-Mar-04 2:25

monrobot13

7-Mar-04 2:25

Thanks for the reply, but I don't particularly want to code the program that way (keeping the user on a control until it validates). I'm not popping up message boxes to notify the user I'm simply putting a * beside the box with problems.

- Aaron

DaBears6-Mar-04 17:53

DaBears

6-Mar-04 17:53

Hi,

I have an SDI app that uses a static splitter. One side of the splitter is a class derived from TreeView and the other side is a class from FormView. When the user clicks on a node in the Tree, I need to send information to be displayed to the other view (CFormView).

I don't know how to pass that information. The document will hold the data, I need to tell my FormView derived View to update its controls (mostly text boxes), but I can't seem to figure it out. I have been through all the Splitter and Doc/View examples on the site but I am stumped.

Thanks,

Mike

Re: Passing information among different views

Neville Franks6-Mar-04 21:16

6-Mar-04 21:16

One way is to call:

UpdateAllViews( CView* pSender, LPARAM lHint = 0L, CObject* pHint = NULL );

from the TreeView. Set pSender to the TreeView and get its CView::OnUpdate() handler to ignore calls to itself. You can also put lHint to good use.

This is likely the most MFC way to do it.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Compiling problem

john.angel6-Mar-04 16:25

john.angel

6-Mar-04 16:25

Hi, i'm working in a Win32 app. It's based on a main file, and a class file. The main file has a window which receives events and must create different instances of the class. There is a global list, where some data is saved. When certain message arrived, the new instance of the class must search for the info previously saved in the global list. The files are:

//**Main.cpp**//
include "Main.h"

SomeFunction(PCHAR Data)
{
RecordList.push_back(Data);
....
}
//**Main.h**//
#include "CX.h"
#include <list>
using namespace std ;
typedef list<PCHAR> List;
static List RecordList;

//**CX.h**//
Class X
{
...
}

//**CX.cpp**//

VOID CX::Function()
{
List::iterator i;
PCHAR Data;
i = RecordList.begin();
Data = *i;
....
}
The compiler print error C2065 in each line where the RecordList or the iterator are used. Even in the main file.
I tried including :

#include <list>
using namespace std ;

in the CX files but this doesn't work either

Any idea?
Tnx

Re: Compiling problem

Prakash Nadar6-Mar-04 16:49

6-Mar-04 16:49

does it works if you remove the static from
static List RecordList

This space is empty.

Re: Compiling problem

john.angel6-Mar-04 16:52

john.angel

6-Mar-04 16:52

Problem solved
http://www.codeguru.com/forum/showthread.php?s=ed2cedde3719d44ef58b38b453c2874b&threadid=262363&highlight=global+variable+in+classes

MFC

Archer2826-Mar-04 15:00

Archer282

6-Mar-04 15:00

well, i just started working with MFC, i made a button, and 2 edit boxes, i cant really do anything dynamic yet so how could i make when i click the button it writes moves something from onde edit box to the other?

Compiler: VC++ 6 Enterprise
OS: Windows ME

Re: MFC

Prakash Nadar6-Mar-04 15:07