Thou shalt have no other gods before the ANSI C standard

From: D. J. Bernstein (djb_at_cr.yp.to)
Date: 02/02/05 

Date: Wed, 2 Feb 2005 21:19:27 +0000 (UTC)

Douglas A. Gwyn wrote:
> The fact is, using calloc to initialize non-integer values is *wrong*

Are you next going to claim that every program using POSIX system calls
is ``wrong''? After all, the C standard doesn't guarantee they'll work!

Perhaps your response will be that the C spec and the POSIX spec are
equally worshipped in your religion. Well, suppose I write a C program
that runs perl---which isn't guaranteed to work by either spec. Is that
program ``wrong''?

I'll readily agree that the all-0-bytes representation of NULL isn't
guaranteed by the C standard. I'll also agree that there was, once upon
a time, an obscure C implementation that, for silly reasons, used a
different representation of NULL. But this doesn't mean that programs
relying on the all-0-bytes representation are ``wrong.'' It simply means
that they won't work with goofy implementations of C.

> and every competent C programmer knows it

The vast majority of C programmers are writing code for PCs, Macs, Suns,
etc., running Windows, Linux, MacOS, BSD, etc., all of which guarantee

   * an all-0-bytes representation of NULL,
   * 8-bit char,
   * 16-bit short,
   * 32-bit int (the 286 is dead), and
   * IEEE single-precision 32-bit float (UNICOS is dead),

among other things. Taking advantage of these guarantees is convenient
for the programmer and doesn't sacrifice any real-world portability.

---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago

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