Cross Class Functions - C / C++ / MFC Discussion Boards

Read/write from a binary file @ specified offsets

27-Jul-01 7:20

Hi there

I'm a Visual C++ newbie and i want to read and write bytes from a file @ specified offsets. Simply how do I do this?

I currently use the following code to do this bit of the programme, but it doesn't let me choose the offset of where I write to, only the value and number of bytes I patch! Please help!!!

==============================================

ofstream path("c:\\windows\\desktop\\debug.dat");
;
char *value_of_patch = "ffff";
int number_of_bytes = 10;

int setmode(int mode = filebuf::binary);
path.setmode(filebuf::binary);

path.write(value_of_patch, number_of_bytes);

================================================
Sample code is appreciated Smile | :)

Best regards,
Richard Edwards

Re: Read/write from a binary file @ specified offsets

Carlos Antollini27-Jul-01 8:18

Carlos Antollini

27-Jul-01 8:18

I wrote this for Read get the number of page in a tiff file.

typedef struct _TiffHeader
{
	WORD Identifier;
	WORD Version;
	DWORD IFDOffest;
}TIFHEADER;

typedef struct _TiffTag
{
	WORD TagId;
	WORD DataType;
	DWORD DataCount;
	DWORD DataOffset;
}TIFTAG;


long CWebBrowApp::GetTiffPageCount(LPCTSTR lpFileName)
{
	TIFHEADER* udtTifHdr = new TIFHEADER;
	WORD NumDirEntries;
	DWORD NextIFDOffset;
	long nPages = 0;
	CFile tFile;
	
	if(tFile.Open(lpFileName, CFile::modeRead | CFile::typeBinary))
	{
		
		tFile.Read(udtTifHdr, sizeof(TIFHEADER));
		
		DWORD lOff = udtTifHdr->IFDOffest;
		
		do 
		{
			nPages++;
			tFile.Seek(lOff, CFile::begin);
			tFile.Read(&NumDirEntries, sizeof(WORD));
			tFile.Seek(NumDirEntries * sizeof(TIFTAG), CFile::current);
			tFile.Read(&NextIFDOffset, sizeof(DWORD));
			lOff = NextIFDOffset;
		} 
		while(NextIFDOffset != 0);		
		
		tFile.Close();
	}

	delete udtTifHdr;

	return nPages;
}

I hope to help you!!!;) Wink | ;)

Good Luck!!!
Big Grin | :-D

Carlos Antollini.

Re: Read/write from a binary file @ specified offsets

C^hris L^osinger27-Jul-01 8:20

C^hris L^osinger

27-Jul-01 8:20

path.seekp(pos);

-c

------------------------------
Smaller Animals Software, Inc.
http://www.smalleranimals.com

Re: Read/write from a binary file @ specified offsets

31-Jul-01 9:58

Thanks for your help!
Sorry to ask again but how do I read INTEGER or LONG length values in from a binary file?
At the moment I can only get single bytes.
Do I use GET or READ?
How to I modify the following code to read an integer length value from address 4110 in the DAT file?

==============================================

ofstream path("c:\\windows\\desktop\\debug.dat");
........................

int pos = 4110;
path.seekg(pos);
int bytevalue = path.get();

================================================

Sorry to be dumb, tried to work it out myself but failed (& no online helpfile)

cheers
Richard Edwards

CListView Not cooperating...

Joseph Dempsey27-Jul-01 6:12

Joseph Dempsey

27-Jul-01 6:12

Does anyone know how to force CListView to select an entire row when you click on an item... by this I mean i insert a certain number of items each with 3 subitems... i want the item AND its subitems to appear highlighted...

Any help would be appreciated.

Joseph Dempsey
jdempsey@cox.rr.com
Joseph.Dempsey@thermobio.com

"Software Engineering is a race between the programmers, trying to make bigger and better fool-proof software, and the universe trying to make bigger fools. So far the Universe in winning."
--anonymous

Re: CListView Not cooperating...

Matt Gullett27-Jul-01 6:20

Matt Gullett

27-Jul-01 6:20

Call the SetExtendedStyle function with LVS_EX_FULLROWSELECT as the parameter.

Re: CListView Not cooperating...

Diarrhio28-Jul-01 3:21

Diarrhio

28-Jul-01 3:21

I don't believe that will do the trick. I think the LVS_EX_FULLROWSELECT parameter only allows you to select a row by clicking anywhere on any column in that row, rather than on just the first column text. It won't actually highlight the row.

To achieve the highlighting, you'll have to custom draw the control yourself, and you can find many examples of that on this site and on codeguru in the listcontrol sections.

best of luck

Cross Class Functions

Matt Newman27-Jul-01 5:50

Matt Newman

27-Jul-01 5:50

I need to access function1 in class2 from class1. Everytime I try to do this i get an error about statically linking. "illegal call of non-static function........ it is Error C2352. Since this function takes values and updates controls based on these values I can't use static functions. Can anyone tell me what to do ? Confused | :confused:

-Matt Newman Suspicious | :suss:

Re: Cross Class Functions

C^hris L^osinger27-Jul-01 5:53

C^hris L^osinger

27-Jul-01 5:53

you can only call non-static (ie. normal) methods on an object if you have an instance of the object.

so, either create an instance of class2 or find an already-exisiting instance of it.

-c

------------------------------
Smaller Animals Software, Inc.
http://www.smalleranimals.com

Re: Cross Class Functions

Matt Newman27-Jul-01 6:04

Matt Newman

27-Jul-01 6:04

you can only call non-static (ie. normal) methods on an object if you have an instance of the object. so, either create an instance of class2 or find an already-exisiting instance of it.
I am a beginner and I am not sure what you mean by create an instance. Could you elucidate this for me?

-Matt Newman Suspicious | :suss:

Re: Cross Class Functions

C^hris L^osinger27-Jul-01 7:05

C^hris L^osinger

27-Jul-01 7:05

This is really one of the basic principles (maybe the most basic principle) in all of Object Oriented programming: you have a set of functions and properties grouped together that comprise an "object". You can tell the object to do something (invoke methods on the object), to report its state, to change its state, etc..

CString myString;

After this statement executes, "myString" is an "instance" of CString. Or, you could say "myString is an object of type CString".

Now you can call CString methods on myString:

BOOL b = myString.IsEmpty();
myString.MakeUpper();

etc..

What you can't do is call (non static) CString methods without having a CString object to call them on:

CString::Reverse();

This statement makes no sense (at all).What are you trying to Reverse? There is no object there. It's a verb without a noun.

-c

------------------------------
Smaller Animals Software, Inc.
http://www.smalleranimals.com

Re: Cross Class Functions

Matt Newman27-Jul-01 8:23

Matt Newman

27-Jul-01 8:23

Now I remember. Thanks for the help and the refresher course.;)

-Matt Newman Suspicious | :suss:

PLEASE HELP !!!! URGENT !!!!!!!!!! save struct in file

27-Jul-01 5:09

This code doing problems in run time, When it read from the file this gets incorrect values in the parameters of the struct. Please ! try find the problem !!!!!!!
class CPerson {
CPerson();

public:
virtual ~CPerson();

public:
dPerson per;
CPerson* pNext;
CPerson* pBack;
};
-------------------------------------------------------------
________________________________________________________________
//cpp file:
-----------------

void CDemo::OnButtonAdd()
{
CFile file;
// CFileException ex;

if(file.Open(strPath, file.modeWrite |file.modeNoTruncate|file.modeCreate ))
{
file.SeekToEnd();
file.Write( &(person.per) , sizeof(dPerson));
MessageBox("************ S A V E D ************** ");
}
}

/************************************************************/
// Read the one first CPerson from the file:
void CDemo::read_person(CFile* persons)
{
CPerson* q = new CPerson;

DWORD dwRead = sizeof(dPerson);

if((*persons).Read(&q->per, sizeof(dPerson)))
{
q->pNext = q->pBack = NULL;
p_head = p_tail = q; //p_head and p_tail are member variables of CDemo - type CPerson*
}
else delete q;
}

/************************************************************/
Cry | :((

Re: PLEASE HELP !!!! URGENT !!!!!!!!!! save struct in file

Joaquín M López Muñoz27-Jul-01 5:37

Joaquín M López Muñoz

27-Jul-01 5:37

Have you tried to add the flag CFile::typeBinary when opening the files?

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

problem with SetActiveView( , ),,??????

mr200327-Jul-01 4:40

mr2003

27-Jul-01 4:40

Hi,,
I have a MDI application. I like to get a pointer to the view of a particular document, and them activate it,,

this is the way that I do it,, but it doesn't work

pDoc= GetDocument();
POSITION pos = pDoc->GetFirstViewPosition();
while (pos != NULL)
{
pView = pCurrDoc->GetNextView(pos);
pCurrView=(CTurboMechView*)pView;
CMDIFrameWnd *pFrame = (CMDIFrameWnd*)AfxGetApp()->m_pMainWnd;
pFrame->SetActiveView(pCurrView,TRUE);
}

Thanks
Confused | :confused:

Ehsan Behboudi

Re: problem with SetActiveView( , ),,??????

Tomasz Sowinski27-Jul-01 4:50

Tomasz Sowinski

27-Jul-01 4:50

I think that you should activate a frame, not a view - this is MDI app, right? Do you have multiple views in one MDI child frame?

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

Re: problem with SetActiveView( , ),,??????

mr200327-Jul-01 6:06

mr2003

27-Jul-01 6:06

i dont' have multiple views in one MDI child frame.
but i have several documents open...
so I like to be able to activate a particular View..
I can get a pointer to the document. and then i can get a pointer to the View of that documents. but i can't activate the view..

any ideas??

Ehsan Behboudi

Re: problem with SetActiveView( , ),,??????

Matt Gullett27-Jul-01 6:14

Matt Gullett

27-Jul-01 6:14

Assuming you have the document pointer

POSITION ViewPos = pDoc->GetFirstViewPosition();
ASSERT(ViewPos);
CView* pView = pDoc->GetNextView(ViewPos);
ASSERT(pView);
pView->GetParentFrame()->BringWindowToTop();

Re: problem with SetActiveView( , ),,??????

mr200327-Jul-01 8:34

mr2003

27-Jul-01 8:34

thank you
it was helpful

Ehsan Behboudi

Adding A Interface

AJ12327-Jul-01 4:37

AJ123

27-Jul-01 4:37

Hi,

I am modifying a DCOM sever, i have written some new functions and would like to package them into their own interface. How do i do this, a sample piece of IDL is shown for one of the interfaces that already exists on the object. Is there anything i need to watch out for? where do i get the uuid from

[

uuid(5E816CCA-628A-4959-B1FE-05465C3393EB),

helpstring("IDocumentVision Interface"),
pointer_default(unique)
]

interface IDocumentVision : IUnknown
{
}

Cheers

Rich

Re: Adding A Interface

Not Active27-Jul-01 8:18

Not Active

27-Jul-01 8:18

You can get the uuid from GUIDGen.exe, should be in the tools folder in your Visual Studio installation. I always add it to the tools menu for easy access.

VC Pre-Build Commands

Steve Thresher27-Jul-01 4:10

Steve Thresher

27-Jul-01 4:10

If I use a prebuild command to auto-generate a source file, can I then add that source file to the current project?

System DSNs

27-Jul-01 4:07

Hi there,

I was wondering if there is anyway to detect what system DSNs are currently configured on a given machine within a Windows Application?

thanks Cry | :((

Re: System DSNs

Not Active27-Jul-01 8:23

Not Active

27-Jul-01 8:23

Look under this reg key: HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI

Background color of CListCtrl

skfnmuislædmufaæoi27-Jul-01 4:03

skfnmuislædmufaæoi

27-Jul-01 4:03

I'm using a CListView-derieved class which displays SQL-results in report style.
I decided to turn the background gray, so I called SetBkColor() in OnInitialUpdate. The problem is, that this backgroundcolor can only be seen in areas, where no items are draw and as a flickering background when scrolling the list. Confused | :confused:

What must be done to override the standard item background color?

Pseudocode is code to demonstrate a concept, not designed to be run.
Like certain Microsoft software.

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