Question Mark Operator

Ruby has a question mark (?) operator that works like so

> ?a
=> "a"
> ?\s
=> " "
> ??
=> "?"
> ?a + ?b + ?c
=> "abc"

It essentially creates single character strings. At least in Ruby 1.9+ it does. In versions of Ruby before 1.9, the ? operator could be used to get the ascii character code of the operand character.

h/t Josh Davey

source