Why does ?A return "A" in ruby

Question

I recently came across this code that calculates "4 * n!"

def moreThanUsual n
    eval [*1..n, 4] * ?*
    # 4 * Math.gamma(n + 1)
end

which made me interested in the ?*, and upon experimentation I saw:

>> ?*
=> "*"
>> ?a
=> "a"
>> ?1
=> "1"
>> ?8
=> "8"
>> ?83
SyntaxError: (irb):32: syntax error, unexpected '?'
    from /usr/local/bin/irb:11:in `<main>'
>> ?ab
SyntaxError: (irb):33: syntax error, unexpected '?'
    from /usr/local/bin/irb:11:in `<main>'

What is this strange operator that only takes one proceeding characterright against it, and changes it into a string?

Yep, it's just short-hand for creating a one-character string in Ruby. Almost no one uses it because it is so obscure. — David Grayson, Jun 27 '16 at 23:02
It's literally the character that takes one character to the right and changes it into a string. — user229044, Jun 27 '16 at 23:04

score 1 · Accepted Answer · answered Jun 27 '16 at 22:58

1

The question mark prefix produces a single character; the one you write right after it.

answered Jun 27 '16 at 22:58

Raffael

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Why does ?A return "A" in ruby

1 Answers1