What does :^ in reduce method mean?

Question

I was doing a challenge on Code Wars where I was given an array "numbers" with several (sometimes repeating) integers and I had to return one unique integer. I passed the challenge but when I looked at all the previously submitted solutions, I noticed this reduce method:

def stray (numbers)
  numbers.reduce(&:^)
end

I know what reduce method generally does but I haven't been able to find what the symbol ^ means. Could anyone please let me know its purpose?

Answer 1

The reduce method is used on arrays to combine all elements of that array into a single item.

The reduce method accepts a starting value and a block of code.

What you are using is a shorthand version of reduce which means the following:

numbers.reduce(&:^)

The & character will attempt to call the method on the argument itself when it is used as a last argument of a method call or definition. The ^ character signifies the bitwise XOR operator.

Inject is also an alias for reduce in Ruby.

You can read more here.