Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • 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
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Code Generator

Language

Generated Code

re = /(?(DEFINE) (?<EXPR> (?&EA) (?&EB) ) (?<EA> \( (?&EXPR) \) | (?&ANY) | (?&PREFIX) (?&EXPR) ) (?<EB> # EXPR beta (?&INFIX) (?&EXPR) | (?&POSTFIX) | ) # Operators (?<INFIX>[+*\/-^]) (?<PREFIX>[+-]) (?<POSTFIX>) # Literals (?<ANY> (?&INT)|(?&STRING)|(?&BOOL)| (?&PROP)|(?&FUNC) ) (?<FUNC> =>\s*\( ((?&EXPR)(,\s*(?&EXPR))*)? \)\s* ({(?&EXPR)}|(?&EXPR)) ) (?<PROP> (?<PALPHA> ([A-Za-z$_][\w$]*)(\( ((?&EXPR)(,\s*(?&EXPR))*)? \))? ) (\.(?&PALPHA))* ) (?<BOOL>true|false) (?<STRING> (["'])([^"\\]|\\.)*?\g{-2} ) (?<INT>\d+) ) ^(?&EXPR)$/xm str = '2+2*(3^5) "halo"+"howjuicavocad" foo.bar(baz).hello => (arg) arg+2' # 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