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From: donn@utah-cs.UUCP (Donn Seeley)
Newsgroups: net.lang.f77
Subject: Re: (do) while loops
Message-ID: <3505@utah-cs.UUCP>
Date: Sun, 27-Oct-85 01:00:47 EST
Article-I.D.: utah-cs.3505
Posted: Sun Oct 27 01:00:47 1985
Date-Received: Tue, 29-Oct-85 00:56:27 EST
References: <144@oberon.UUCP>
Organization: University of Utah CS Dept
Lines: 27


	From: mcooper@oberon.UUCP (Michael Cooper)

	My question is: doesn't Unix (ANSI) f77 support a (do) while
	statement?  ...

This is really two questions: (1) Does the ANSI standard define
DO-WHILE loops (or '!' comments or DEFINE-FILE or zillions of I/O
parameters or QIO calls)?  Ans.:  No.  (2) Does Unix f77 support this?
Ans.:  Unix f77 compilers which are descendants of the original AT&T
Feldman/Weinberger compiler support very few syntax extensions; in
particular they recognize only the DO loop which is defined in the ANSI
standard.  Some manufacturers (Convex is one, I'm told; DEC, curiously,
is not) advertise 'VMS-compatible' Unix compilers, which presumably
accept DO-WHILE and other extensions.  My perception is that these
manufacturers are in the minority.

Moral: if your VMS compiler has a flag to turn off non-ANSI extensions,
use it or be prepared to use VMS forever.  I'm not sure whether to
blame the ANSI committee for not adopting these extensions or DEC for
adding them (and I'm not familiar enough with the history of the
standard to know whether these extensions were considered)...

Fortran-8x will probably support QIO calls,

Donn Seeley    University of Utah CS Dept    donn@utah-cs.arpa
40 46' 6"N 111 50' 34"W    (801) 581-5668    decvax!utah-cs!donn