From mboxrd@z Thu Jan  1 00:00:00 1970
From: Erik Mouw <J.A.K.Mouw@its.tudelft.nl>
To: alasdair@wildcat.demon.co.uk
Cc: 97nv46@skola.kiruna.se, gcc@gcc.gnu.org
Subject: Re: Volatile constants?
Date: Wed, 29 Mar 2000 10:05:00 -0000
Message-id: <200003291805.UAA08004@duteinh.et.tudelft.nl>
References: <14562.16912.888978.578471@wildcat.demon.co.uk>
X-SW-Source: 2000-03/msg00764.html

On Wed, 29 Mar 2000 18:49:04 +0100 (BST), Alasdair Baird wrote:
>  > > #define abs2(x) (x<0 ? -x : x)
>  > 
>  > <nitpick>
>  > You should define this as:
>  > 
>  >   #define abs2(x) ((x) < 0 ? (-x) : (x))
>  > 
>  > Rationale: see what happens with your version if you use abs2(2 - 3). The
>  > extra parentesis enforce the correct operator precedence.
> 
> I think that you might find the following to actually be correct though:
> 
>    #define abs2(x) ((x) < 0 ? -(x) : (x))

Yes, you're absolutely right.


Erik

-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy