Re: swapping two numbers

[David Westbrook]

Michael R. Wolf wrote:

I was digging through some old code and came across a proof that I had done
that you can swap two numbers in place (i.e. without using an external
temporary value).
Of course, in Perl, we can just do this:
($x, $y) = ($y, $x)
 

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)