^ operator in Swift

Question

Looking through the hashable protocol, and to make a matrix location struct to conform:

struct MatrixLocation: Hashable {
    let row: Int
    let col: Int
    var hashValue: Int { return row.hashValue ^ col.hashValue }
}

The hash value has the ^ operator.

What is the ^ operator in Swift?

score 2 · Accepted Answer · answered Mar 17 '18 at 02:45

2

^ is the XOR operator in Swift. Basically it compares the bits of the two operands, and for each bit, it sets the corresponding bit of the result to 1 if one of the two input bits is 1, but the other is 0. If both bits are 1 or both bits are 0, it sets the bit in the result to 0.

So if you have 0x49 ^ 0x13, that would be 01001001 XOR 00010011, which would come out to 01011010, or 0x5a.

answered Mar 17 '18 at 02:45

Charles Srstka

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Because it's a quick and easy way to combine the two existing hash values in a way that comes out relatively unique. If you just ORed them you'd end up with a disproportionate number of 1 bits, and if you ANDed them, you'd end up with a disproportionate number of 0 bits. Each bit has a 50/50 chance of being 0 or 1 in an XOR operation, unlike those two. – Charles Srstka Mar 17 '18 at 03:02
3

XOR is quick and easy, but not actually a good choice for combining hash values. Check out [this answer](https://stackoverflow.com/a/27952689/77567) for an example of a much better hash combiner. – rob mayoff Mar 17 '18 at 03:51

^ operator in Swift

1 Answers1