coding style for who.c

Allan Clark allanc at
Mon Mar 13 19:19:47 UTC 2006

On 3/14/06, Rob Landley <rob at> wrote:
> On Monday 13 March 2006 1:54 pm, Robin Farine wrote:
> > On Sunday March 12 2006 06:24, Rob Landley wrote:
> > > If one of them is a constant, it emits no warning.
> >
> > Indeed. I could not reproduce any gcc warning with 'if (a & b)', 'a'
> > and 'b' being constants or variables. Must be due to a mistake
> > while picking mushrooms.
> It might have produced a warning on older versions.
> if (a & b) doesn't work quite like if (a && b), but it's not the obvious
> error
> that if (a = b) tends to be.  If you restrict yourself to logic values
> rather
> than arbitrary numbers, and don't mind losing the short circuit behavior,
> then something if (a==b & c==d) will in fact work as expected.

(Rob gets two copies, reply/reply-all typo that compilers don't catch)

In large projects that actually use code-inspection, and hunt/kill
warnings,  double-parenthesis

    if (( a = b )) ...

... and LHS constants:

    if (NULL == (fd = open (... )) )

... tend to show "yeah, I meant that when I wrote that, it's not a coding
typo" even if they don't add obvious readability.  In addition
(double-parens) to quieting the warning, or (NULL == x) using the compiler
to avoid (a = 0) errors, this coding style lets us skim quickly to things we
need to question. it's not a bad habit, BB or otherwise :)

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