Messages in this thread | | | Date | Wed, 21 Nov 2001 01:57:13 -0500 | From | Stevie O <> | Subject | Re: if (a & X || b & ~Y) in dasd.c |
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At 08:38 PM 11/19/2001 +0100, Peter T. Breuer wrote:
>"bill davidsen wrote:" > > If the code does what I think it does, it works as written. However, I > > usually would throw in parenthesis on something like this to be sure > > that the next person reading the code won't waste time thinking about > >Which is WHY you do not put in parentheses.
<snip snip>
So instead of using extra parentheses, we should include a copy of your response in every potentially ambiguous location instead?
Two C constructs that have bitten me in the glutinous maximus on more than one occasion:
mem_address = mem_base + page_index << 12; // Wrong!
if ( bit_mask & BIT_FLAG == 0) { flag_not_set(); } // Wrong!
Of course C has precedence. It's not always obvious. And the difference between this
x = y + z << 2;
and
x = (y + z) << 2;
is that the 2nd doesn't make me have to remember the relative precedences of + and <<.
-- Stevie-O
REAL kernel hackers use # cat > /vmlinuz and # insmod /dev/stdin
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