Re: Writing to and reading from same file = crash :(

From:

"Tom Serface" <tom.nospam@camaswood.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 17 Sep 2008 09:08:19 -0700

Message-ID:

<BE69BAF3-5A18-4892-8C1D-990D2394DDF2@microsoft.com>

How long (how many characters) are the lines in the file? Is there a chance
that the line is too long. You may try using the version of ReadString that
has a max characters option to see if that helps. Also, if you are using
tabs for a delimiter you may want to put \t rather than trying to embed an
tab character (I assume that's what shows up here as _T(' ') . You could
also step through with the debugger if this happens regularly and see what
the strLine contains when the crash occurs.

Are the file reads and writes synchronized somehow or are they competing for
the same file continuously? There may be a problem with that as well if you
are moving the file pointer around in the same file object (src?) If you
have two file object then there may be a problem with committing the data to
the file (caching?)

Tom

"vorange" <orangepic@yahoo.com> wrote in message
news:9db37258-9758-4800-949d-4ffc380a67c7@i20g2000prf.googlegroups.com...

Hi,
   I am running 2 modaless windows. One which is writing to a file
(opened in share mode), the other reading from that file. After
running for a while successfully (about 30 seconds), my program
crashes.

I have a feeling my program is crashing at the part where I'm trying
to read the file.

Basically I am reading line by line from the file, tokenizing each
line (by its tab) and putting each item (3 numbers separated by tab)
into a CArray. Do you see anything wrong with what's below? :

while(src.ReadString(strLine)
{
   while(AfxExtractSubString(resToken, strLine, s, _T(' ')))
   {
      _stscanf( resToken, _T("%f %lf"), &floatnum, &doublenum );

      // some logic to put each tokenized items into CArray
   }
}

The compiler flags a line from some windows file when it crashed. The
line where it says IAtlStringMgr...etc. Is it related to my code
above or is this telling me the problem is somewhere else?

void Empty() throw()
{
       CStringData* pOldData = GetData();
       IAtlStringMgr* pStringMgr = pOldData->pStringMgr;
       if( pOldData->nDataLength == 0 )
       {
           return;
       }

Thank you

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