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From: peters@yang.earlham.edu
Newsgroups: comp.lang.pascal,comp.os.msdos.programmer
Subject: Re: Statusof a msdos file after dos error
Message-ID: <6032@yang.earlham.edu>
Date: 14 Dec 90 11:03:05 GMT
References: <2350@bnlux0.bnl.gov>
Organization: Earlham College, Richmond, Indiana
Lines: 28

In article <2350@bnlux0.bnl.gov>, kushmer@bnlux0.bnl.gov (christopher kushmerick) write> After a file has been opened (Via assign, reset/rewrite) what is its 
> Here is the exact situation:
> 
> turbo pascal 5.0
> 
> I open a file. the reset/rewite occurs with success.
> 
> Now I do an operation, and it fails, perhas, for example, because the
> user took the diskette out of the drive. What is the status of the file?
> Do I have to close it? Can I close it? should I close it?
> 
> Chris Kushmerick
> kushmer@bnlux0.bnl.gov    <===Try this one first
> kushmerick@pofvax.sunysb.edu 

The answer depends on whether you opened the file with reset or rewrite.
If you opened it with reset, to read it, then a failed operation will leave
the file uncorrupted (unless the failure is due to a dog eating the physical
disk, etc.).  If you opened it with rewrite or append, to write to it, then
the chances are very good that any write/ln's performed between the opening
of the file and the failed operation did not make it to the disk.  In TP,
closing a file is the way to insure that writes are flushed from the buffer
and sent to the disk.  Verify this by opening a file with rewrite, sending
some text to the file with write/ln, and watching the light on the disk drive;
it will not glow until the close command is processed.

Peter Suber.  Depts. of Philosophy, Computer Science.  Earlham College.
Richmond, Indiana 47374.  317-983-1214.  peters@earlham.bitnet.