C / C++ / MFC

18-Jul-02 2:54

Hi,

I want to overwrite 32 caracters in a text file...
For the moment I do :

CStdioFile newFile;
//
// Open in Read/Write mode, etc...
//
newFile.SeekToBegin();
for(i = 0; i < 9; i++) {  // set pointer position to 9th line (32 caracters)
   if(!newFile.ReadString(str, MAX_BUFFER_SIZE)) {
      MessageBox("End of file prematurely detected");
      return;
   }
}
newFile.WriteString(strCRC + "\n");  // overwrite the 9th line (32 caracters)
newFile.Close();

but this doesn't work... Confused | :confused:

I try to understand... Anybody can help me ?
Thanks in advance.

Hello World!!! Smile | :)

from Raphaël

Anonymous18-Jul-02 3:04

18-Jul-02 3:04

I don't know what arguments do You pass in the Open() method, but it could be a matter of open mode if You used
CFile::modeRead
instead of
CFile::modeReadWrite

...just guessing...

Krzysztof Szczech
[ CoY0te ]

Raphael Kindt18-Jul-02 3:08

18-Jul-02 3:08

I use this:

CFileException exc;
if(!newFile.Open(strFileName, CFile::modeCreate | CFile::modeReadWrite | CFile::typeText, &exc) ) {
  exc.ReportError();
  return;
}

Next, I fill the file... And then I try to overwrite the same file.

Hello World!!! Smile | :)

from Raphaël

Anonymous18-Jul-02 3:26

18-Jul-02 3:26

Sorry, I've missed that Read/Write in Your source code.
But the problem is quite strange. I doubt I'll be able to help, but please take a look at my question above (about CMenu), maybe You could help me with this.

[ CoY0te ]

Fredrik Skog18-Jul-02 3:29

18-Jul-02 3:29

Shouldn't you add modeNoTruncate to the flags?
If you use modeCreate only, then the file will be truncated to zero length.

Cheers,
Fredrik

<right>Sonork ID: 100.11430:PhatBoy

"Felix qui potuit rerum cognoscere causas."

Raphael Kindt18-Jul-02 3:39

18-Jul-02 3:39

I don't have to add this flag because I fill the file with caracters first (after his creation), and then I overwrite it.
Thus, initially empty or not it's not a problem.

Hello World!!! Smile | :)

from Raphaël

Fredrik Skog18-Jul-02 3:43

18-Jul-02 3:43

Then what is your problem? You are a bit unclear.
Do you get exceptions, if so, what do they say?

Cheers,
Fredrik

<right>Sonork ID: 100.11430:PhatBoy

"Felix qui potuit rerum cognoscere causas."

Raphael Kindt18-Jul-02 3:52

18-Jul-02 3:52

I don't have any Error or Warning and no more exceptions...
My goal is simply a partial rewriting of a text file. Thus some line change but keep the same number of caracters...
My question is: How to do that? Confused | :confused:

Hello World!!! Smile | :)

from Raphaël

Fredrik Skog18-Jul-02 4:01

18-Jul-02 4:01

You had code for that, right?
So I ask again: what part is not working?

Cheers,
Fredrik

<right>Sonork ID: 100.11430:PhatBoy

"Felix qui potuit rerum cognoscere causas."

Fredrik Skog18-Jul-02 4:16

18-Jul-02 4:16

An idea: can't you just append the CRC to the end of the file? (::SeekToEnd() and then ::Write())

Cheers,
Fredrik

<right>Sonork ID: 100.11430:PhatBoy

"Felix qui potuit rerum cognoscere causas."

Raphael Kindt18-Jul-02 4:32

18-Jul-02 4:32

No I must respect the RBT file format (it's a text file) because this file is used by another program (who program the Flash component of an electronic board)...
yeap... OMG | :OMG:

Hello World!!! Smile | :)

from Raphaël

Raphael Kindt18-Jul-02 4:13

18-Jul-02 4:13

The code:

CStdioFile newFile;
CFileException exc;
if(!newFile.Open(strFileName, CFile::modeCreate | CFile::modeReadWrite | CFile::typeText, &exc) ) {
   exc.ReportError();
   return;
}
//
// I fill the file here... then I compute the Checksum
//
newFile.SeekToBegin();
for(i = 0; i < 9; i++) {  // set pointer position to 9th line (32 caracters)
   if(!newFile.ReadString(str, MAX_BUFFER_SIZE)) {
      MessageBox("End of file prematurely detected");
      return;
   }
}
newFile.WriteString(strCRC + "\n");  // rewrite the 9th line (32 caracters)
newFile.Close();

Compilation is OK...
Finaly the 9th line (of the file) is not rewrited. Why?

Hello World!!! Smile | :)

from Raphaël

Raphael Kindt18-Jul-02 4:48

18-Jul-02 4:48

I change my method... I'll create a buffer then I'll copy this buffer inside the file...

Thanks neverthless

Hello World!!! Smile | :)

from Raphaël

Bill Wilson18-Jul-02 8:42

Bill Wilson

18-Jul-02 8:42

The code above positions to the start of the 10th line. It reads the first 9. If you really want to position to the 9th line, try for (i=0;i<8 ...

Raphael Kindt18-Jul-02 21:05

Change the length of bitmap image arbitrary?

18-Jul-02 21:05

Yes but my first line is the 0th line... Thus that's OK because the 9th line is the 10th in the reality (As you say)... Wink | ;)

But, concerning the overwriting of a file, my conclusion is that "that doesn't work" because you must be at the end of the file, and thus you can only Add line to a file (in the end). The reason is that the Write and Read methods are both sequential. What's strange is that no error was detected (for the compilation and execution). Moreover is that in the watch window, during the debug, the pointeur to the file shows well that he wrote(overwrote). But after the execution, when I open the file, no modification was found.... Strange... but it's the live... Smile | :)

Thanks...

Hello World!!! Smile | :)

from Raphaël

chen18-Jul-02 2:39

chen

18-Jul-02 2:39

Hi,

I meet one problem, That is, i have a bmp image displayed under
a ruler. Now the ruler can be resized with the changes of the x-axis and/or y-axis. I would like to see the bmp image also changed in length or height when the ruler is changed.
But
how to change the length of the bmp image displayed on a button
arbitrary? Is there any method for doing this?

Thanks in advance!

chen

Re: Change the length of bitmap image arbitrary?

includeh1018-Jul-02 5:04

includeh10

18-Jul-02 5:04

how do u display ur bitmap? use BitBlt?
if use StretchBlt, u can do u want.

includeh10

Re: Change the length of bitmap image arbitrary?

chen18-Jul-02 19:58

chen

18-Jul-02 19:58

Thanks for your reply.
But there is no StretchBlt() function in my used CDib class, where
can i find a proper one of this function?

Thanks in advance!

chen

Cwaitcursor and onpaint messages

Anonymous18-Jul-02 2:12

18-Jul-02 2:12

Hi,

I have a dialog based application, in which when the user clicks a particular button, a time consuming process gets executed. Till the process completes, the user should not be allowed to operate any other button on the dialog.
Step 1
So, in the handle for the button click I add code like:
OnButton()
{
CWaitCursor myCursor;
//Long processing
}
But now, if the application is minimized, it cannot be seen again, ie the dialog becomes completely unresponsive.

Step2

So I created a thread to do the long processing. But the problem is I have to wait for the thread to finish before exiting the button handle...

Step 3
Then to be able to process message, after the AfxBeginThread, I added a message loop. Now the final code looks like:
OnButton()
{
AfxBegindThread()
while( WaitForSingleObjecT(handle, 2) = timeout || getmessage())
{
dispatchmessage()
}
}

But still this does not seem to work. Can any one help me with this?

Thanks !

ActiveMovie4

Anonymous18-Jul-02 2:11