Living in a state of accord.
I'm Adrian Sutton, otherwise known as AJ.
I'm the CTO at Ephox, coming to grips with what that means and how to do it. I've recently moved over to the UK to help increase Ephox's presence in Europe. You can follow my travel stories at "The Suttons".
In my spare time I'm busy exploring the sights of the UK and Europe.
Contact:
adrian@symphonious.net
+44 7 525 806 170
+1 (650) 292 9659 x717
More Ephox Blogs
While I'm waiting for Eclipse to do an update: What's the one value you can pass to Math.abs(int) and get a negative value from?
Just ran into a bug caused because of it - fortunately it was picked up by the tests even before I checked in.
September 14th, 2006 at 10:46 am
That would be Integer.MIN_VALUE :)
September 14th, 2006 at 10:51 am
Oh, and its not like I figured that one out on my own, was one of the many interesting cases listed in a book I think I’ve mentioned before: Java™ Puzzlers: Traps, Pitfalls, and Corner Cases, by Joshua Bloch, Neal Gafter. If you find this puzzle interesting I highly recommend the book. It’s up on safari - http://search.safaribooksonline.com - you can get a trial account for 2 weeks I think so won’t even cost you anything.
September 14th, 2006 at 11:17 am
Yep, in twos-compliment notation, you can always go one value more negative than you can positive (ie: if you can get to +3, you can get to -4).
September 14th, 2006 at 4:59 pm
And for the nerd in me, it took me ages to understand twos-compliment so i love any chance to explain what’s going on, humour me if you will:
Say we have a number system with only 3 bits using twos-compliment. max number you get is 3, min is -3. the bit pattern for each number is:
000 0
001 1
010 2
011 3
100 -4
101 -3
110 -2
111 -1
two’s complement flips the sign on a number by inverting the bit pattern and then adding one. For example, 2 is 010. flip the bits it becomes 101, add one you get 110, which as the table shows is -2. To show the original problem with an example, -4 is 100. flip the bits and you get 011, add 1 and voila, you get 100.
The other cool (i really am a geek) case is negating 0. 000 flips to 111, we add 1 and we get 1000, but since we only have 3 bits, the leading 1 is lost and we end up with 000. So with twos-complements there are always 2 numbers that when negated will equal themself: 0 and the min.
September 14th, 2006 at 5:02 pm
Gah, hit submit while checking that post. min is -4 not -3.