Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!bobmon
From: bobmon@iuvax.cs.indiana.edu (RAMontante)
Newsgroups: comp.lang.c
Subject: Re: comma operator:  keep away?
Message-ID: <19926@iuvax.cs.indiana.edu>
Date: 22 Apr 89 18:49:56 GMT
References: <19913@iuvax.cs.indiana.edu> <10092@smoke.BRL.MIL>
Reply-To: bobmon@iuvax.cs.indiana.edu (RAMontante)
Organization: malkaryotic
Lines: 23

gwyn@brl.arpa (Doug Gwyn) <10092@smoke.BRL.MIL> :
-	[ me ]
->Is there a circumstance in which the comma operator is required, where
->the compound statement cannot be broken into multiple statements?
-
-You've got to be kidding -- a comma expression is an expression,
-whereas multiple statements are not an expression.  Thus the comma
-operator is useful in contexts where semicolon-terminated statements
-would not be.  Look at the definition of putc() in most implementations
-of <stdio.h> for an example.


"You've got to be kidding?" In fact someone else suggested getchar() as
an example.  Looking at the Turbo C stdio.h, and the ULTRIX v1.7 stdio.h,
I find that neither one uses a comma in getc, getchar, putc, putchar, or
anywhere else, except to separate parameters.

Nonetheless I think I get the idea, but that doesn't mean that the code
wouldn't work without the comma (does it?) -- couldn't the same semantics
be reproduced by a series of statements culminating in the final
expression of the parentheses (presumably for assignment purposes)?

I said "required", not "useful".