Re: "Interesting" C behaviours

From: Malcolm (malcolm_at_55bank.freeserve.co.uk)
Date: 11/27/04 

Date: Sat, 27 Nov 2004 06:51:06 -0000

"Rennie deGraaf" <ca.ucalgary.cpsc@degraaf> wrote
> In the last few days, I have discovered two "interesting" behaviours of
> the C language, both of which are apparently correct. Could someone
> please explain the reasoning behind them?
>
> 1. The operators '^', '&', and '|' have lower precedance than '==',
> '!=', '>=", etc.
>
You'd have to ask K and R about this. The problem is that the language was
designed by two people in a back room somewhere, and once set, the
precedence rules are very difficult to change.
>
> 2. In C99, the expression 'a%b' where a<0 and b>0 will return a negative
> result (K&R lets this be machine dependent).
>
That would probably be driven by architecture. The idea is that a % b would
compile to a single machine instruction (on K and R's original platform).
Just a guess, but I suspect this is the motivation.

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