re = /^(?!.{51,})(\w+\s+\w+ ?)$/m
str = 'firstname lastname
first name last name
123456789 1234567890123456789012345678901234567890
123456789 12345678901234567890123456789012345678901'
# 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