Swift 1.2 (Xcode 6.3) removed xor '^' operator for Bool value?

Question

This sample code on Xcode 6.3 ...

var str1 = ""
var str2 = ""
if str1.isEmpty ^ str2.isEmpty {
  // do something.
}

displays the following error.

'^' is unavailable: use the '!=' operator instead

I cannot find the spec in Apple documentation. Is this specification (and I'll have to lump it)?

I cannot find it in http://swiftdoc.org/ neither in the header files, so probably yes. — Dániel Nagy, Apr 10 '15 at 07:32
Yes. I know it. Currently the link of release notes is dead link, so I wanted to know if it is a specification's change. — Mitsuaki Ishimoto, Apr 10 '15 at 10:29
IMO Swift should have a "^^" operator because "!=" is not nearly as intuitive. Read: "one but not the other" vs. "is not equal to". "!=" works, but it's more obscure. — David James, Mar 31 '19 at 12:01

score 30 · Answer 1 · answered Apr 10 '15 at 07:39

30

Assuming you are trying to use a logical XOR, a != should serve your purpose. The ^ is a bitwise XOR. So makes sense that Apple removed it for bool values.

answered Apr 10 '15 at 07:39

lostInTransit

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So how do you apply XOR to three booleans simultaneously? – jowie Nov 13 '15 at 11:31
7

@jowie xor has no definition for more than two elements at the same time, how would you expect it to work? – Daniel Nov 26 '15 at 08:02
6

@jowie (a != b) != c should do it. – Tim Vermeulen Dec 28 '15 at 08:25
4

@jowie XOR is associative. `(a ⊕ b) ⊕ c` = `a ⊕ (b ⊕ c)`, so you can pick either one – Alexander Jan 19 '17 at 11:41

score 14 · Accepted Answer · answered Apr 10 '15 at 14:02

It's clearly intentional:

$ echo ':print_module Swift' | swift -deprecated-integrated-repl | fgrep "use the '!=' operator instead"

shows:

@availability(*, unavailable, message="use the '!=' operator instead") func ^=(inout lhs: Bool, rhs: Bool)
@availability(*, unavailable, message="use the '!=' operator instead") func ^(lhs: Bool, rhs: Bool) -> Bool

Swift 1.2 (Xcode 6.3) removed xor '^' operator for Bool value?

2 Answers2

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