Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!BRL.MIL!phil
From: phil@BRL.MIL (Phil Dykstra)
Newsgroups: comp.sys.sgi
Subject: Re:  Fortran bug?
Message-ID: <8912041433.aa29614@SPARK.BRL.MIL>
Date: 4 Dec 89 19:33:54 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 23

> K&R state that blank, tab, nl and comments are treated
> collectively as "white space" character. (K&R 1978, p.179)

Sure enough, I just looked and both the original and 2nd edition
state this.  However, the early Unix C compilers (and even most
current ones) would replace comments by nothing at all rather than
by a space [to be precise, the C preprocessor would do this].  This
behavior was/is often exploited for token concatenation.

ANSI adopted the original spec that comment = whitespace and thus
provided the new '##' operator for concatenation.

Note that one of the actions of the GNU C compiler "-traditional"
flag is to:

        * In the preprocessor, comments  convert  to  nothing  at
          all,  rather  than to a space.  This allows traditional
          token concatenation.

So, SGI is just following the convention that most UNIX C compilers do.
Strict ANSI compilers however will not do this.

- Phil