re = /(^[A-Za-z][A-Za-z0-9\.\-\_]+$)|(^[\w\-\.\+]+@([\w-]+\.)+[\w-]{2,4}$)/m
str = 'User1.2.3
simpleuser123
simpleuser_123
simpleuser-123
1baduser
.baduser
_baduser
1bob-is.great_999+456@gmail.com'
# 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