On Sun, Jun 25, 2006 at 12:31:19AM -0700, Larry Rosler wrote:
From: Philippe BooK Bruhat
Sent: Saturday, June 24, 2006 04:10
To: fwp@perl.org
Subject: Re: swapping two numbers
Le vendredi 23 juin 2006 ? 17:40, Samy Kamkar ?crivait:
Although x could overflow in this case, where
Although x could overflow in this case, where it wouldn't with an xor,
right?
Leonid Grinberg wrote:
not in-place cause it's 3 lines, but does not use an external temporay
value, and should be language-independent:
x = x + y
y = x - y
x = x - y
(IIRC my high school BASIC teacher taught
On Jun 23, 2006, at 5:01 PM, David Westbrook wrote:
Michael R. Wolf wrote:
not in-place cause it's 3 lines, but does not use an external
temporay value, and should be language-independent:
x = x + y
y = x - y
x = x - y
(IIRC my high school BASIC teacher taught us that)
This works:
Le vendredi 23 juin 2006 à 17:40, Samy Kamkar écrivait:
Although x could overflow in this case, where it wouldn't with an xor,
right?
I've quickly tried to overflow it, but I didn't manage to break it.
It looks like even if you overflow x with the first addition, you
cross the border in the
M I was digging through some old code and came across a proof that I
had done
M that you can swap two numbers in place (i.e. without using an
external
M temporary value).
M Of course, in Perl, we can just do this:
M ($x, $y) = ($y, $x)
M But I was challenged (at a GSLUG meeting) to do it in
