Re: [Exim] more 4.11 problems :-/

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Συντάκτης: Philip Hazel
Ημερομηνία:  
Προς: Kevin P. Fleming
Υ/ο: exim-users
Αντικείμενο: Re: [Exim] more 4.11 problems :-/
On Mon, 16 Dec 2002, Kevin P. Fleming wrote:

> Not to beat a dead horse there, but I think the operative word here is
> "evaluation". The ++ and -- operators are not part of the "evaluation" of the
> condition, at least not in the strictest sense of that word.


I think you will find that they are. The value of the condition is the
value of the expression, and these operators are part of the expression.
The value of ++x is the incremented value of the variable x. It has a
value; therefore, there is an "evaluation". A quote from the standard:

"The result is the new value of the operand after incrementation. The
expression ++E is equivalent to (E+=1)."

> I could be way off base here, in which case never mind...


I'm afraid I'm sure that you are way off base. Here's a longer quote
from the Standard:

"Unlike the bitwise binary & operator, the && operator guarantees
left-to-right evaluation; there is a sequence point after the evaluation
of the first operand. If the first operand compares equal to 0, the
second operand is not evaluated."

... and in the discussion of the ++ operator: "The side effect of updating
the stored value of the operand shall occur between the previous and the next
sequence points."

> I'd bet it could work either way legally.


I beg to differ, I'm afraid.

Regards,
Philip

--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.