RE: C and side-effects

From: Robert M. Love (
Date: Wed May 03 2000 - 18:45:01 EST

> Rik van Riel wrote:
> > I'm not that good at C, mas aren't expressions with side-effects
> > ill-defined? How can we be sure (short of tracking the gcc
> > mailing lists) that i will be incremented after the left part of
> > the test?
> Because it is defined in the C standard?
> Rik

maybe im reading the thread wrong, but Cesar is saying the code
        while ((mm->swap_cnt << 2 * (i + 1) < max_cnt) && i++ < 10)
does not guarentee that the expression to the left of && occurs prior to
"i++" -- and he is Right,
because the C standard does *not* specify this. proof is in K&R, where they
explicitly mention compiler design or optimization can change compound
statement ordering in the resulting machine code. thus, i agree an
alternative should be considered in the kernel.

Robert Love

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