comma operator: keep away?

[Doug Gwyn]

In article <19926 at iuvax.cs.indiana.edu> bobmon at iuvax.cs.indiana.edu (RAMontante) writes:
>I find that neither one uses a comma in getc, getchar, putc, putchar, or
>anywhere else, except to separate parameters.

Ok, I picked a bad example.  However, many macros need to accomplish
more than one thing and cannot do so without the aid of some such
trickery as
	((expr1) & 0 | (expr2))
which is more simply expressed as
	(expr1, expr2)

>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)?

No!  A series of statements cannot be used as a subexpression.

Of course -- as I just demonstrated -- there are ways to avoid ever using
a comma operator, but then all you really need is a Turing machine, right?
So why does C provide more than the logical minimum?  It's because it was
designed to be USED for real programming, and matters of convenience are
quite relevant for that.