Re: man 3 switch

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On 11/16/09 13:54, quoth Rick Stevens:
> On 11/14/2009 01:55 PM, Frank Cox wrote:
>> On Sat, 14 Nov 2009 14:50:57 -0500
>> Steven W. Orr wrote:
>>> There's nothing wrong with perl having all kinds of perldoc pages.
>>> But perl
>>> comes from one place. C, OTOH could come from lots of places besides
>>> FSF and
>>> the switch statement in gcc may not be exactly the same as the switch
>>> statement in some other dialect.
>> As C is an ISO standard, I sincerely doubt there would be any
>> difference in the
>> syntax and behaviour of the keywords between C compilers on any Unix-like
>> operating system.
> Incorrect.  C, for example, does not guarantee the order of evaluation
> of arithmetic operators of equal precedence in the same statement (in
> other words, is something like "a + b + c" evaluated left to right, or
> right to left?).  This can have significant effects if some of the
> operands have "side effects"
> Another example is that a null pointer (or the value "NUL") is not
> necessarily zero, only that it is guaranteed to not point at any valid
> datum.
> C allows quite a bit of leeway to the compiler implementation.

I think I disagree on this one. We jumped from standardization of keywords to
how operators perform. I quote from page 53 of K&R: Table of Precedence and
Associativity of Operators: a + b + c *always* goes from left to right. K&R is
not the standard, but does the standard say otherwise? Lots of things are up
to the compiler writer, but I'd be surprised if this was one of them. Sometime
people worry about things like

a++ + b++ + c++

but even there, the precedence and the associativity are defined. In this case

a++ + b++ + c++

becomes (in psuedo stack code):

a b +
c +

because binary + is lower precedence than ++.


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steveo at

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