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From: dmurdoch@watstat.waterloo.edu (Duncan Murdoch)
Newsgroups: comp.lang.pascal
Subject: Re: TP6 - Standard Out got closed
Message-ID: <1991May13.224950.26135@maytag.waterloo.edu>
Date: 13 May 91 22:49:50 GMT
References: <382@galileo.rtn.ca.boeing.com>
Sender: news@maytag.waterloo.edu (News Owner)
Organization: University of Waterloo
Lines: 26

In article <382@galileo.rtn.ca.boeing.com> rfh3273@galileo.rtn.ca.boeing.com (Dick Harrigill) writes:
>I've just experienced a strange error with TP6.  I'm using a function
>that I've successfully used for years to check the existance of a file:
>
> FUNCTION this_file_exists (VAR s:string) : boolean;
> VAR f:file;
> BEGIN
>  {$I-}
>  assign(f,s); reset(f);
>  this_file_exists:=(IOError=0);
>  close(f);
>  {$I+}
> END;
>
>This week, for the first time, passing a bad file name to this file
>somehow closed standard output when the close(f) statement was run.
>A successive statement such as  writeln('Hi')  yeilds a runtime error
>103 - file not open.   

If the file doesn't exist, the Close will fail - this will cause subsequent
I/O requests to be ignored, because you didn't clear IOError.  I imagine
the problem in this case was that you tried a reset on output after
running this function.  It was ignored, so output stayed closed.

Duncan Murdoch
dmurdoch@watstat.wateroo.edu