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From: john@ghostwheel.unm.edu (John Prentice)
Newsgroups: comp.lang.fortran
Subject: Re: Fortran vs. C for numerical work (SUMMARY)
Message-ID: <1990Dec5.183112.2928@ariel.unm.edu>
Date: 5 Dec 90 18:31:12 GMT
References: <1990Dec4.011220.9302@ccu.umanitoba.ca> <26434:Dec404:42:4990@kramden.acf.nyu.edu> <1990Dec4.190148.4026@ariel.unm.edu> <2642@charon.cwi.nl>
Sender: John K. Prentice
Organization: University of New Mexico Math Dept., Albuquerque, NM
Lines: 32

In article <2642@charon.cwi.nl> dik@cwi.nl (Dik T. Winter) writes:
>...  Everything goes through the C preprocessor
>because of machine pecularities (as some parts are written in assembler this
>is necessary).  However, the C preprocessor is also used to avoid compiler
>bugs.

   and after some more comments ...

>3.  Especially if you have a large body of code, be prepared to customize it
>    to every platform you may encounter.  Allow the use of preprocessors to
>    do this (C preprocessor, m4, your own special built macro processor, etc.).
>

For what it is worth, I would second this suggestion.  We used to use a
home grown preprocessor called SAIL which we wrote back in 1972 before such
things were generally available.  Now we use the C preprocessor for this 
(the C preprocessor is pretty limited in capabilities, but it is usually
sufficient.  The big problem with the C preprocessor is that damn near
every one I have used is a little different!  For example, the one that
Borland sends out with their Turbo C and Turbo C++ will left justify every
line of the processed code (dumb!).  The Decus C preprocessor issued by
the C User's Group does the same thing.  Then you find that the Cray C
preprocessor can't handle all the preprocessor constructs listed in 
version 2 of K&R (i.e., the ANSI version).  The Sun versions seem to
pretty much work okay.  All this can be a real pain in using the
C preprocessor however unless you limit yourself to really simple
uses).  We have not had to use the C preprocessor to handle bugs however,
so far we use it mostly to separate machine dependent code (for example,
array constructs for the CM2 versus loops on every other computer).

John Prentice
john@unmfys.unm.edu


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