Hi Colin

As I read your problem, you are dealing with a formatted file (whatever format, in records).

In my implementation (Lahey) I am able to use REWIND(#) to completely rewind the open file (# is allocated in the OPEN).
Most of the following operations must surely be standard conforming ?!

BACKSPACE(#) 'rewinds' the open file one record - from the start of the current record to the start of the previous record.
That is, if you have just READ a record from that file, and you BACKSPACE your next read will be the same record.

You can skip a record by doing a dummy read: READ(#,*) ! Reading no variable.
As far as I am aware, even a list-directed write will only form one record in a 'formatted' file type.

You can repeat the BACKSPACE or dummy reads in a DO loop to accommodate particular needs.

I hope I have not misread what you you were seeking.
I am sure that others will correct any real or apparant error in this Email.



Kind regards to all

Gaz


-----Original Message-----
From: Colin Millar [mailto:[log in to unmask]]
Sent: Thursday, 20 February 2003 9:14 PM
To: [log in to unmask]
Subject: Backspace and file position.


Hello all,

I am relatively new to programming, and my only language is F90. As I
understand the backspace function, the current position in the file must be
known, say n. And then the file is rewound to its first record, and n-1
successive reads performed. So I was wondering if there was an intrinsic
routine to access the current file position for use later, or would it be
easier to encase the read statement in a routine with a SAVE attributed
integer, say count, and use count as an index?

One other query, if you would be so kind as to help, is why you cannot use
backspace to skip over a record written using list-directed formatting. I
am using sequential access, with position set to default ('ASIS'). I am
under the impression that a record corresponds to a line on an ASCII file,
and when writing using list directed output, all data is written to the one
record. With this understanding I see no difference between explicit
formatting and list-directed formatting, with concerns to backspace. Is my
understanding a bit confused? Any help would be appreciated.

Thanks in advance,

Colin Millar.

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Colin P Millar Tel: +44 (0)1224 876544
Fisheries Scientist Direct: +44 (0)1224 295507
Fisheries Research Services Fax: +44 (0)1224 295511
Marine Laboratory, PO Box 101
375 Victoria Road, Torry [log in to unmask]
Aberdeen AB11 9DB www.marlab.ac.uk
UK

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