Codecabulary Home / Learn Ruby / Ruby Regexes
Regular Expressions are patterns often used to ensure user input matches specific criteria (e.g. to ensure a user has entered a valid email address).
Patterns in Ruby are specified using /pattern/
/Perl|Python/ # Perl or Python
/\d\d:\d\d:\d\d/ # A time, such as 12:35:56Ruby uses the =~ match operator to match strings against regexes
email = "stupidAOLacct590@aol.com"
email =~ /\d{3}/ # If matches, returns the start position of the match
> 13
email =~ /\d{4}/ # If no match, returns nil
> nil
Since nil is returned for no match, regexes can be used in conditional piping:
email = "brett.shollenberger@gmail.com"
if email =~ /\b[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-z]{2,4}\b/
puts "Logged in."
end
Check out the Regex Cheat Sheet for more info on regular expressions.