Regular Expressions 101

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  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
  • A character except: a, b or c
  • A character in the range: a-z
  • A character not in the range: a-z
  • A character in the range: a-z or A-Z
  • Any single character
  • Alternate - match either a or b
  • Any whitespace character
  • Any non-whitespace character
  • Any digit
  • Any non-digit
  • Any word character
  • Any non-word character
  • Match everything enclosed
  • Capture everything enclosed
  • Zero or one of a
  • Zero or more of a
  • One or more of a
  • Exactly 3 of a
  • 3 or more of a
  • Between 3 and 6 of a
  • Start of string
  • End of string
  • A word boundary
  • Non-word boundary

Regular Expression
No Match


Test String



Code Generator

Generated Code

re = /^(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})/im str = ' (one-letter local part) "much.more unusual" "" "very.(),:;<>[]\\".VERY.\\"very@\\\\ \\"very\\".unusual" admin@mailserver1 (local domain name with no TLD) #!$%&\'*+-/=?^_`{}| "()<>[]:,;@\\\\\\"!#$%&\'*+-/=?^_`{}| ~.a" " " (space between the quotes) example@localhost (sent from localhost) (see the List of Internet top-level domains) user@com user@localserver user@[IPv6:2001:db8::1] © ? Invalid email addresses[edit] (no @ character) (only one @ is allowed outside quotation marks) a"b(c)d,e:f;g<h>i[j\\k] (none of the special characters in this local part are allowed outside quotation marks) just"not" (quoted strings must be dot separated or the only element making up the local part) this is"not\\ (spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash) this\\ still\\"not\\\\ (even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes) (double dot before @) with caveat: Gmail lets this through, Email address#Local-part the dots altogether (double dot after @)' subst = 'QuestionText = "$1",' result = str.gsub(re, subst) # Print the result of the substitution puts result

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: