Comments on: Tips and tricks for bitwise arithmetic http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/ Stay curious! Fri, 29 Aug 2008 05:08:07 +0000 http://wordpress.org/?v=2.2.2 By: salman http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14220 salman Fri, 15 Feb 2008 22:14:47 +0000 http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14220 by the way nice article. by the way nice article.

]]> By: salman http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14219 salman Fri, 15 Feb 2008 22:14:06 +0000 http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14219 i would wish you would write the following line sum(o.valid = 1 * i.value) as valid_value, as sum((o.valid = 1) * i.value) as valid_value, because for some programming lang '*' has greater precedence than '='. the expression becomes sum(o.valid = (1 * i.value)) as valid_value, it just seems confusing. P.S. if i put my foot in mouth, just give me a shout. i would wish you would write the following line

sum(o.valid = 1 * i.value) as valid_value,

as

sum((o.valid = 1) * i.value) as valid_value,

because for some programming lang ‘*’
has greater precedence than ‘=’.
the expression becomes

sum(o.valid = (1 * i.value)) as valid_value,
it just seems confusing.

P.S. if i put my foot in mouth, just give me a shout.

]]> By: salman http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14218 salman Fri, 15 Feb 2008 22:09:53 +0000 http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-14218 set @bitset = case when @number & @bit 0 then 1 else 0 end; — bad! set @bitset = (@number & @bit) / @bit; — good! could these also be written as set @bitset = ((@number & @bit) = @bit); — better? we avoid an expensive division. Is there any particular reason for the division? set @bitset = case when @number & @bit 0 then 1 else 0 end; — bad!
set @bitset = (@number & @bit) / @bit; — good!

could these also be written as

set @bitset = ((@number & @bit) = @bit); — better? we avoid an expensive division.

Is there any particular reason for the division?

]]> By: James Curran http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-4613 James Curran Mon, 26 Feb 2007 17:18:29 +0000 http://www.xaprb.com/blog/2005/09/28/bitwise-arithmetic/#comment-4613 <p>It should be noted that "if (number & mask != 0)" is merely "confusing, Bad practice!" only if mask represent a single bit of mutually exclusive flags. If "mask" can have several bits set, then it's just plain wrong.</p> It should be noted that “if (number & mask != 0)” is merely “confusing, Bad practice!” only if mask represent a single bit of mutually exclusive flags.

If “mask” can have several bits set, then it’s just plain wrong.

]]>