On 2009-08-07 13:01:55 -0400, Daniel Keep <daniel.keep.li...@gmail.com> said:
Michel Fortin wrote:
I always wondered why there isn't an XOR logical operator.
binary logical
(a & b) => (a && b)
(a | b) => (a || b)
(a ^ b) => (a ^^ b)
a | b | a ^^ b | a != b
---+---+--------+--------
F | F | F | F
F | T | T | T
T | F | T | T
T | T | F | F
That's why.
For this table to work, a and b need to be boolean values. With && and
||, you have an implicit convertion to boolean, not with !=. So if a ==
1 and b == 2, an hypothetical ^^ would yeild false since both are
converted to true, while != would yield false.
But I have another explanation now. With && and ||, there's always a
chance that the expression on the left won't be evaluated. If that
wasn't the case, the only difference in && vs. &, and || vs. | would be
the automatic convertion to a boolean value. With ^^, you always have
to evaluate both sides, so it's less useful.
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
