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From: a228arig@cdfb.utoronto (Tak Ariga)
Newsgroups: comp.sys.apple
Subject: Finding if a file exists on a disk in Applesoft BASIC.
Message-ID: <8704190657.AA12796@cdfb.toronto.edu>
Date: Sun, 19-Apr-87 01:57:40 EST
Article-I.D.: cdfb.8704190657.AA12796
Posted: Sun Apr 19 01:57:40 1987
Date-Received: Tue, 21-Apr-87 00:43:54 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 27


Can anyone inform me how I can find out if a given file exists on the
disk or not through a BASIC (or a ML routine) program?  I have this
simple data base program that I wrote, and I don't want to overwrite
files.

Right now, I am using VERIFY to see if the file name exists.  If it doesn't
exists (the desired case), it causes an error.  I use ONERR GOTO and use
an error handling routine to deal with it.  The problem is, it seems to
clear some GOSUB stacks, and when it encounters a RETURN, it comes back
with 'RETURN WITHOUT GOSUB ERROR', even though it was within a subroutine.
I know this is a VERY bad way of doing things, but I wrote it when I was
still in high school and knew very little of programming, and the only
way I could figure out how to do it.

I imagine I have to read the VTOC nicely, but I don't know how to do that.
Help please.  Thanks.

--Tak

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