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From: wsb@boise.Eng.Sun.COM (Walt Brainerd)
Newsgroups: comp.lang.fortran
Subject: Re: Dates for the different versions of FORTRAN?
Summary: Zero trip DO
Message-ID: <140686@sun.Eng.Sun.COM>
Date: 15 Aug 90 15:47:24 GMT
References: <3093.26c6b1cd@cc.curtin.edu.au> <9008151155.AA11309@thep.lu.se>
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In article <9008151155.AA11309@thep.lu.se>, magnus@THEP.LU.SE (Magnus Olsson) writes:
> 
> The later versions of Fortran (IV, 66, 77) are reasonably downward
> compatible with each other, even though there are some discrepancies,
> such as the handling of a degenerate DO loop (DO 10 I=1,0 ...).

The STANDARD Fortran 77 was compatible with the STANDARD Fortran 66
because "zero-trip" DO loops were not legal in Fortran 66.  Although
many compilers allowed them as an extension (e.g., IBM), not all of
them got it wrong.  For example, CDC 1604 Fortran executed a "zero-trip"
DO loop zero times (not once).

Speaking of upward compatibility, I have a copy of the original Fortran
manual for the IBM 704.  It contains a nice example of a complete
Fortran program, almost all of which is completely legal Fortran 90.
One counterexample is a line containing the FREQUENCY statement.
--
Walt Brainerd        Sun Microsystems, Inc.
wsb@eng.sun.com      MS MTV 5-40
                     Mountain View, CA 94043
                     415/336-5991