Error in previous posting

[Doug Gwyn]

In article <1991Apr4.160608.13628 at mccc.edu> pjh at mccc.edu (Peter J. Holsberg) writes:
>x[i++] *= y; is treated as
>x[i++] = x[i] * y; instead of
>x[i++] = x[i++] * y;
>Where/how is this described?
>Interestingly, very few textbooks mention it at all, probably because
>they introduce assignment operators before side effects.

Strange -- the first textbook I picked up to check this (K&R2) says
almost precisely the same thing as the C standard.  I suggest you
consider using K&R2 (Second Edition of Kernighan & Ritchie's "The C
Programming Language") as your C textbook in place of whatever you
have been using.

In the C standard X3.159-1989, the relevant specification is exactly
where one would think it should be, in section 3.3.16.2 (Compound
Assignment) Semantics.  Since it is quite brief and elegant, I'll
quote it here, even though I think you should look at p.50 of K&R2:

	A compound assignment of the form E1 op= E2 differs from the
	simple assignment expression E1 = E1 op (E2) only in that
	the lvalue E1 is evaluated only once.