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
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

re = /(?:\bdigit-|\s|^)(\d{4})(?=[.?\s]|-digit\b|$)/m str = 'Lorem ipsum 3400-digit, sit amet 5000 consectetur adipisicing elit. Natus, explicabo 6700? Itaque iure ipsum laboriosam, ex nemo delectus iste quia cupiditate digit-9134? Iste nam digit-2456 at voluptate est 8456-digit? At excepturi quis voluptatibus 7500. Lorem ipsum $5000 dolor sit amet consectetur adipisicing elit. Obcaecati tempora dolorum repellat reiciendis cum soluta deserunt ex voluptatibus, nam illum veniam £5550 quidem aperiam sequi, nostrum sed? Quidem eveniet maiores #5550 autem. https://codepen.io/pen/5000/3454 follows either digit- or whitespace and is followed by either ., ?, -digit or whitespace.' # 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