Re: [BUG] Bad #define, nonportable C, missing {}

Alexander Viro (viro@math.psu.edu)
Thu, 22 Nov 2001 07:03:28 -0500 (EST)


On Thu, 22 Nov 2001, Horst von Brand wrote:

> Stevie O <stevie@qrpff.net> said:

> > But x++ is postincrement though. That means the value of 'x' is inserted,
> > and after the expression is evaluated, x is incremented. Right?
>
> Nope. x++ increments x sometime (not defined when) after taking the value.
>
> x = x++ % y
>
> is wrong: There is just one sequence point at the end of the expression,
> and x is modified twice in between (++ and =).

Or look at it that way: both
tmp = x % y; x++; x = tmp;
and
tmp = x % y; x = tmp; x++;
are possible interpretations with different results. And as usual, compiler
is allowed to do literally anything whenever it sees such beast.

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