ruby is character
#Use a regular expression that matches letters & digits:
def letter?(lookAhead)
lookAhead.match?(/[[:alpha:]]/)
end
def numeric?(lookAhead)
lookAhead.match?(/[[:digit:]]/)
end
#These are called POSIX bracket expressions, and the advantage of them is
#that unicode characters under the given category will match. For example:
'ñ'.match?(/[A-Za-z]/) #=> false
'ñ'.match?(/\w/) #=> false
'ñ'.match?(/[[:alpha:]]/) #=> true
#You can read more in Ruby’s docs for regular expressions.
#https://ruby-doc.org/core/Regexp.html