C / C++ / MFC Discussion Boards

«_Superman_»22-Jan-10 16:55

22-Jan-10 16:55

It has always been called as recycle bin.
People may not understand you if you call it by other names.

Anyway, try doing an invalidate on the desktop.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Replacing some bytes in a file in binary mode

sunny_vc21-Jan-10 20:55

sunny_vc

21-Jan-10 20:55

Hi,
I have a file which is in binary mode.(I am using stdio functions fwrie,fread,fseek)
I have to read this file in binary mode and needs to replace some of the bytes in this file.
It contains around 1000 entries with 2 bytes each.
I know the location of bytes which is to be changed, like 100th entry.
Is there anyway to change that specific bytes, without copying in to other file.
As I have small memory I can not copy into other file and recopy with changed bytes.
So on the fly i want to change specific bytes.

please tell me if any method is there to do this.?

Regards,
Sunil Kumar

Re: Replacing some bytes in a file in binary mode

CPallini21-Jan-10 21:24

CPallini

21-Jan-10 21:24

You may open the file for read/write (i.e. "r+") go to intended position with fseek and change the byte content with fwrite.
Smile | :)

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.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: Replacing some bytes in a file in binary mode

sunny_vc21-Jan-10 21:34

sunny_vc

21-Jan-10 21:34

yeah.i've used the same thing.But that is not working.

Regards,
Sunil Kumar

Re: Replacing some bytes in a file in binary mode - fixed, thanks to superman

CPallini21-Jan-10 21:44

CPallini

21-Jan-10 21:44

My code (beware: error checking omitted for concision)

FILE * fp = fopen("foo.bin", "rb+");
fseek(fp, 10, SEEK_SET);
fwrite("#", 1, 1, fp);
fclose(fp);

is working fine.
Smile | :)

modified on Friday, January 22, 2010 6:43 AM

Re: Replacing some bytes in a file in binary mode

«_Superman_»21-Jan-10 22:35

«_Superman_»

21-Jan-10 22:35

Except that for binary you could do a "rb+".

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Re: Replacing some bytes in a file in binary mode

CPallini22-Jan-10 0:43

CPallini

22-Jan-10 0:43

Oh, thanks...
Smile | :)

Re: Replacing some bytes in a file in binary mode

iceman861621-Jan-10 21:48

iceman8616

21-Jan-10 21:48

did you remember fflush() the buffers?

Re: Replacing some bytes in a file in binary mode

Stuart Dootson21-Jan-10 23:05

Stuart Dootson

21-Jan-10 23:05

As superman's said elsewhere in this thread, use binary mode when you open the file, using

FILE * fp = fopen("foo.txt", "rb+");

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

CodeProject MVP for 2010 - who'd'a thunk it!

File Manipulation

Chandrasekharan P21-Jan-10 20:03

Chandrasekharan P

21-Jan-10 20:03

I am doing an application where i am writing something to an excel sheet. Initially i am writing into 2 rows and coloums. i have the heading and then the values and then closing the file. Now at a later point of time i need to open the same file and append. starting writing from the third row. How can i do that?

Re: File Manipulation

Rajesh R Subramanian21-Jan-10 20:16

Rajesh R Subramanian

21-Jan-10 20:16

Use excel automation. Refer to one of those numerous samples provided in MSDN.

Or you could use something like BasicExcel - A Class to Read and Write to Microsoft Excel[^].

“Follow your bliss.” – Joseph Campbell

Re: File Manipulation

Cedric Moonen21-Jan-10 20:27

Cedric Moonen

21-Jan-10 20:27

What is the format of your file ? A CSV file or really an excell spreadsheet ? Are you using excell automation ?

Cédric Moonen
Software developer

Charting control [v3.0]
OpenGL game tutorial in C++

Re: File Manipulation

David Crow22-Jan-10 4:17

David Crow

22-Jan-10 4:17

Chandru080 wrote:
Now at a later point of time i need to open the same file and append. starting writing from the third row. How can i do that?

How did you write to the second row?

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Handle to a video played in a video player

lazy_panther21-Jan-10 19:42

lazy_panther

21-Jan-10 19:42

Hi,

I have a video playing in a video player. Irrespective of video player, I need the handle to the video being played. I have user-specified screen co-ordinates, now I need to convert the screen co-ordinates into frame co-ordinates of the video. To convert screen co-ordinates to video-frame co-ordinates and to further process video frames, I need handle to the video.

I am using Visual Studio and C++ for Win32 programming.

Any pointer?

Thanks

Create function error in CView Class

diarabit21-Jan-10 19:16

diarabit

21-Jan-10 19:16

I found a technical document for adding multiple view to a single document project.
http://msdn.microsoft.com/en-us/library/s199bks0%28VS.80%29.aspx[^]

I made a form view and tried to create it in my project.

When I tried it first, it was succeeded. But when I made it again I got an error message.

It is my code copy from MSDN document.

CView*	pActiveView = ((CFrameWnd*)m_pMainWnd)->GetActiveView();
	m_pOldView = pActiveView;
	m_pSearchView = (CView*)new CSearchMember;
	
	CDocument*	pCurrentDoc = ((CFrameWnd*)m_pMainWnd)->GetActiveDocument();

	CCreateContext newContext;
	newContext.m_pNewViewClass = NULL;
	newContext.m_pNewDocTemplate = NULL;
	newContext.m_pLastView = NULL;
	newContext.m_pCurrentFrame = NULL;
	newContext.m_pCurrentDoc = pCurrentDoc;

	UINT viewID = AFX_IDW_PANE_FIRST+1;
	CRect rect(0,0,0,0);

	m_pSearchView->Create(NULL, NULL, WS_CHILD, rect, m_pMainWnd, viewID, &newContext);
	m_pSearchView->SendMessage(WM_INITIALUPDATE, 0, 0);

In debugging mode, I could find a place occurred error.

BOOL CFormView::Create(LPCTSTR /*lpszClassName*/, LPCTSTR /*lpszWindowName*/,
	DWORD dwRequestedStyle, const RECT& rect, CWnd* pParentWnd, UINT nID,
	CCreateContext* pContext)
{
	ASSERT(pParentWnd != NULL);
	ASSERT(m_lpszTemplateName != NULL);

	m_pCreateContext = pContext;    // save state for later OnCreate

#ifdef _DEBUG
	// dialog template must exist and be invisible with WS_CHILD set
	if (!_AfxCheckDialogTemplate(m_lpszTemplateName, TRUE))
	{
		ASSERT(FALSE);          // invalid dialog template name
		PostNcDestroy();        // cleanup if Create fails too soon
		return FALSE;
	}

Because of m_plszTemplateName, this error is occurred.
But I don't know how do I solve.

Please advise for me.

Re: Create function error in CView Class [modified]

Nelek21-Jan-10 22:28

Nelek

21-Jan-10 22:28

Are you wanting to create the additional views on the fly? or creating them in edition time (for instance a CFormView in Resource.h) and attaching / opening them in run-time? With or Without MFC?

If the second there is another approach to get it, I used it in VC6 with MFC. But it is quite long to explain, if it is not what you want / need.

Regards.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpfull answers is nice, but saying thanks can be even nicer.

modified on Friday, January 22, 2010 4:52 AM

Re: Create function error in CView Class

diarabit22-Jan-10 2:12

diarabit

22-Jan-10 2:12

I already made a formview class with MFC. I want when I push the button(like as menu or toolbar), my application's view is changed from basic view to the formview made by me.

So I found that document from MSDN, I tried. But I got a error in Create function in CView. I don't know why that error is occurred. Just guess, it would be because of m_lpszTemaplateName.

Finally, I wanna make the additional view, and show that in my application, when I occur an event like as push a button or toolbar. The application view have to be changed between basic view and formview I made.

Re: Create function error in CView Class [modified]

Nelek22-Jan-10 2:32

Nelek

22-Jan-10 2:32

Take a look into the search[^] for more general info.

To add a different View to the running application (note the "add") you can check this[^] message I wrote quite a time ago and the other I point out in it, about this topic.

To do what you want of just changing the view you could improve/override one of my methods doing that when one view opens, then you go and close the previous one.

I hope it helps you.

EDIT: Searching for another thing I found this[^] I forgot to comment the step 2 of this link into my answers. In fact it is an important step missing. But as he says the code won't compile correctly, but it has the basics and you can complete it with my answers above.

Regards.
--------
M.D.V. Wink | ;)

modified on Friday, January 22, 2010 9:51 AM

Generate Random Number between min and max range and where numbers can't repeat themselves.

Le@rner21-Jan-10 19:06

Le@rner

21-Jan-10 19:06

Hi all,

i want to generate generate random number in given minimum and maximum number range like 1 to 20;

i m using this.

srand((unsigned)time(0)); 
    int random_integer; 
    int lowest=1, highest=20; 
    int range=(highest-lowest)+1; 
    for(int index=0; index<20; index++){ 
        random_integer = lowest+int(range*rand()/(RAND_MAX + 1.0)); 
        cout << random_integer << endl; 
    }

but this generate some repeated numbers.

i want to generate random number but not repeated.

please help me for this.

thanks.

To accomplish great things, we must not only act, but also dream;
not only plan, but also believe.

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

Adam Roderick J21-Jan-10 19:17

Adam Roderick J

21-Jan-10 19:17

I think you just check with srand CRT functions, Please check this link, it shows how you can generate different numbers [^]

Величие не Бога может быть недооценена.

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

Le@rner21-Jan-10 19:28

Le@rner

21-Jan-10 19:28

its generate any numbers,i want to generate numbers with in provide range.

To accomplish great things, we must not only act, but also dream;
not only plan, but also believe.

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

Adam Roderick J21-Jan-10 19:36

Adam Roderick J

21-Jan-10 19:36

It can be done with it
just check this code below.

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

   int i;

  // srand is used to generate different number on each startup of generation.
   srand( (unsigned)time( NULL ) );

   /* Display 10 numbers. */
   for( i = 0;   i < 10;i++ )
   // For the range of 0 to 20 you can use
      printf( "  %6d\n", rand()%20 );

	return nRetCode;
}

Величие не Бога может быть недооценена.

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

C^hris L^osinger21-Jan-10 19:25

C^hris L^osinger

21-Jan-10 19:25

if i had to do this, i'd use a std::set to keep track of numbers that have been generated.

std::set < int > foo;
for (int i=0;i<20;i++)
{
    int z = rand() % 100;
    if (foo.find(z) == foo.end())
    {
        foo.insert(z);
        TRACE("+%d\n", z);
    }
    else
    {
        TRACE("skip %d\n", z);
    }
}

image processing toolkits | batch image processing

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

Le@rner21-Jan-10 19:31

Le@rner

21-Jan-10 19:31

error generated

error C2039: 'set' : is not a member of 'std'

To accomplish great things, we must not only act, but also dream;
not only plan, but also believe.

Re: Generate Random Number between min and max range and where numbers can't repeat themselves.

Rajesh R Subramanian21-Jan-10 19:34

Rajesh R Subramanian

21-Jan-10 19:34

Le@rner wrote:
error C2039: 'set' : is not a member of 'std'

You should #include <set>

“Follow your bliss.” – Joseph Campbell

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.