Portable Languages (was: Expression sequencing query)

[Jason Zions]

dik at mcvax.uucp (Dik T. Winter) writes:
> And so should it.  Once I required the expression (A - B) - C evaluated
> exactly that way.  It didn't do so.  However, after removing the
> parenthesis it was evaluated the way I wanted.  Counterintuitive?

Not counterintuitive - BROKEN. Although C may rearrange the order of
evaluation with respect to + * & ^ and |, it may not do so w.r.t. operators
which aren't associative and commutative.

Rearranging (A - B) - C is just plain wrong.

References:
H&S Section 7.11, page 190
K&R Section 2.12, page 49

Note that both references state that reordering is permitted only for the
associative and commutative operators; they do not mention the names of the
operators for which reordering is forbidden.
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