re = /^(0\d|1\d|2[0-4]):(0\d|[1-5]\d)(?::(0\d|[1-5]\d))?(?:.(00\d|0[1-9]\d|[1-9]\d{2}))?$/m
str = 'Format : [hours]:[minutes]:[seconds].[milliseconds]
21:21:21.123
21:21:21
21:21'
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html