Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!yale!cmcl2!stealth.acf.nyu.edu!brnstnd
From: brnstnd@stealth.acf.nyu.edu
Newsgroups: comp.lang.misc
Subject: Re: NOT Educating FORTRAN programmers to use C
Message-ID: <9738@stealth.acf.nyu.edu>
Date: 23 Jan 90 18:46:28 GMT
References: <17036@megaron.cs.arizona.edu> <14203@lambda.UUCP>
Reply-To: brnstnd@stealth.acf.nyu.edu (Dan Bernstein)
Distribution: usa
Organization: IR
Lines: 38

In article <14203@lambda.UUCP> jlg@lambda.UUCP (Jim Giles) writes:
> From article <17036@megaron.cs.arizona.edu>, by gudeman@cs.arizona.edu (David Gudeman):
> You just made it.  In C there is _NO_DIFFERENCE_ between a pointer and
> an array.  In these other languages, there _IS_ a difference!

The only problem with aliasing is parallel optimization. C compilers for
vector machines provide directives to indicate that arrays x and y don't
overlap. Fortran doesn't even have a standard way to specify extensions.

> Also, as a less important point, C doesn't let me declare array arguments
> to procedures if they are multidimensional and the array bounds in each
> dimension may change from call to call.

Hopefully the next ANSI C will allow foo(m,a) int m; char a[][m]. As is,
it's some extra work for the programmer and, as you point out, probably
some missed optimizations.

  [ parentheses ]

If you really want to force evaluation order, use a temporary variable.
C's as-if optimization is logical and powerful; if a compiler provides
as many inline mathematical functions as Fortran, it can optimize them
just as well.

  [ assignment as an expression ]

I've found C's expressions to be useful syntactic devices. Sometimes
I've wished for even more: something analogous to a = b the same way
that a++ is analogous to ++a. I find it difficult to believe that the
presence of these operators decreases productivity.

The only thing about C that bothers me is its control structures. Any
language that doesn't terminate all its control structures should throw
out its syntax and commit suicide (pun not intended). There aren't any
named loops or multilevel breaks. It's not worth leaving C for that
non-Fortran called Fortran 8X (90, whatever), but it's a pain.

---Dan