re = /^CTC\sN\+(?:123\d{9}|(?!123)\d{10,12})\/?(EN|FR)?$/m
str = 'CTC N+6534567890/FR
CTC N+123456789012/FR
CTC N+1234567890120/FR
CTC N+1234567890/FR
'
# 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