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From: cunniff@hpfcso.HP.COM (Ross Cunniff)
Newsgroups: comp.lang.fortran
Subject: Re: another side effect question
Message-ID: <9080006@hpfcso.HP.COM>
Date: 21 Aug 90 15:18:45 GMT
References: <968@nikhefh.nikhef.nl>
Organization: Hewlett-Packard, Fort Collins, CO, USA
Lines: 22

> Speaking of internal I/O, how come you can't do list-directed formatting
> in an internal I/O statement (or, if you can, how long has this been
> true so I can bitch to a vendor)?

Well, most venders do allow it; however, FORTRAN 77 disallows it because
FORTRAN 77 never made clear how list-directed I/O was to be done.
Specifically, it is impossible to know how many digits a vendor may
choose to print, how many spaces (or other separators) the vendor may
choose to use, etc., etc.  Why they didn't specify this is beyond
me (that old 'Prior Art' thing, probably.  They didn't want to break
all the existing implementations out there...)

The result of this unpredictability is that you can never know if
your list-directed output will fit in the string you give for
internal I/O.  This doesn't seem to bother those vendors and
users who have been doing it all this time.

> Peter da Silva

				Ross Cunniff
				Hewlett-Packard Colorado Language Lab
				cunniff@hpfcla.hp.com