My ISP was unable to accept mail from me this weekend, so
I could read the postings, but could not respond. I'm
still catching up.
> > (1*(2+3))*(5-4) = 5
> > OR
> > (1*(2+3))*(4-5) = -5
> >
>
> Good question. This might be 'implementation dependent'...
> But I think 5-4 would be be the standard
> way: apply MINUS to pop() = 5 and pop() = 4 => (- 5 4) = 5 - 4
>
>
> Hans
This is governed by the rules of association. The simplest
ambiguous case is
3 - 1 - 1
which could have a result of 3 or 1, depending on the order done.
My copy of "The C Programming Language" has a marker on page 49,
where the 15 different types of operators are listed, together
with their precedence and direction of association.
In general, I think that anyone who depends upon this table
should be taken out and shot. However, there are common
idioms that depend on the fact that comparison (==, > and
the like) bind more tightly than && and ||, so you will see
if (x == 0 || x == 1)
Of course, this is question about precedence, not association.
I will never knowingly give a problem that depends on
knowledge of this kind of factoid, or upon the direction
of association, as I can't keep them straight myself.
You should sprinkle enough parenthesis that the reader
or compiler is never in doubt about your intentions.
- jeff parker
