jas@druxy.UUCP (12/18/83)
Re: I would have to disagree with chris as to what should be assigned by:
char *in, *out, buf[];
in = buf;
out = &(*in++);
since he forgot the parentheses. Given the parentheses, out SHOULD
be set buf+1; that is, 'in' is incremented BEFORE the & operator is
applied.
-- Dave Olson (fortune!olson)
Dave, I believe you are mistaken. Perhaps we can finally set this question
to rest by explicitly listing the order of operations when evaluating
&(*in++):
1. Evaluate 'in'.
2. Increment 'in'. This is a side effect, which does not affect the
evaluation of the expression &(*in++).
3. Dereference the value produced by step 1. The result is an lvalue
of type char (I am using 'lvalue' as defined by Kernighan and Richie
in section 5 of Appendix A of *The C Programming Language*). The
value of this result is the character pointed to by 'in' before
incrementing, i.e., buf[ 0 ].
4. Take the address of the value produced by step 3. The result has
type 'pointer to char' (or 'char *', if you prefer); its value is
&buf[ 0 ], or buf.
Step 2 seems to be the only real bone of contention. Section 7.2 of
Appendix A of *The C Programming Language* states: "When postfix ++
is applied to an lvalue, the result is *the value of the object referred
to by the lvalue*. *After* the result is noted, the object is
incremented...." (my emphasis). I see no ambiguity in this sentence.
In my opinion, this subject has now been beaten to death, so here's
hoping I've just had the last word ( :-) ).
-- Jim Shankland
ihnp4!druxy!jas