Re: [FWP] Golf (7 strokes is par!)

[Ariel Scolnicov <ariels@compugen.co.il>]

Jeff Pinyan <jeffp@crusoe.net> writes:

> Challenge: determine if $_ is an integral power of 2 (1,2,4,8,16,...)
> 
>   if (YOUR CODE HERE) { print "$_ is a power of 2" }
> 
> I have it down to 7 characters.  Can anyone beat that?
> 

I can equalise, having read K&R, and assuming it's "unless" not "if":

print"$_ is a power of 2"unless$_&$_-1;

Anybody have a reference for this trick which predates K&R (1st ed.)?

-- 
Ariel Scolnicov        |"GCAAGAATTGAACTGTAG"            | ariels@compugen.co.il
Compugen Ltd.          |Tel: +972-2-6795059 (Jerusalem)	\ We recycle all our Hz
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