In languages like C (and not Perl) where it sometimes makes sense to use this method for swapping values, it will work just fine even if the values are the same. I'm unsure what you mean by "overlap." To see that it will work, try it with all four combinations of 2 bits:

 A | B | A = A^B | B = A^B | A = A^B | A | B 
===|===|=========|=========|=========|===|===
 0 | 0 | 0 = 0^0 | 0 = 0^0 | 0 = 0^0 | 0 | 0
---+---+---------+---------+---------+---+---
 0 | 1 | 1 = 0^1 | 0 = 1^1 | 1 = 1^0 | 1 | 0
---+---+---------+---------+---------+---+---
 1 | 0 | 1 = 1^0 | 1 = 1^0 | 0 = 1^1 | 0 | 1
---+---+---------+---------+---------+---+---
 1 | 1 | 0 = 1^1 | 1 = 0^1 | 1 = 0^1 | 1 | 1
[download]

See? It works fine even when the values are equal.

But, don't do it in perl!

-sauoq
"My two cents aren't worth a dime.";

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