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 = /^(?!(10|127|169\.254|192\.168|172\.(2[0-9]|1[6-9]|3[0-1])|(25[6-9]|2[6-9][0-9]|[3-9][0-9][0-9]|99[1-9]))\.)[0-9]{1,3}(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/m str = 'Public ranges 1.0.0.0-9.255.255.255 11.0.0.0-100.63.255.255 100.128.0.0-126.255.255.255 128.0.0.0-169.253.255.255 169.255.0.0-172.15.255.255 172.32.0.0-191.255.255.255 192.0.1.0/24 192.0.3.0-192.88.98.255 192.88.100.0-192.167.255.255 192.169.0.0-198.17.255.255 198.20.0.0-198.51.99.255 198.51.101.0-203.0.112.255 203.0.114.0-223.255.255.255 ------OK------ 1.1.1.1 9.255.255.255 11.0.0.0 126.255.255.255 128.0.0.0 169.253.255.255 169.255.0.0 172.15.255.255 172.32.0.0 192.167.255.255 192.169.0.0 -----NOT OK----- 10.0.0.0 10.255.255.255 127.0.0.0 127.255.255.255 169.254.0.255 169.254.255.255 172.16.0.0 172.31.255.255 192.168.0.0 192.168.255.255 Not including test nets ' # 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