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

r"
"
gm

Test String

Code Generator

Language

Generated Code

re = /<li><a href=\"(?:(?!#sequence_only).)*\">(.*)<\/a>/m str = ' <!DOCTYPE html> <!-- The following setting enables collapsible lists --> <p> <a href="#human">Human</a></p> <p class="collapse-section"> <a class="collapsed collapse-toggle" data-toggle="collapse" href=#mammals>Mammals</a> <div class="collapse" id="mammals"> <ul> <li><a href="#alpaca">Alpaca</a> <li><a href="#armadillo">Armadillo</a> <li><a href="#sequence_only">Armadillo</a> (sequence only) <li><a href="#baboon">Baboon</a> <li><a href="#bison">Bison</a> <li><a href="#bonobo">Bonobo</a> <li><a href="#brown_kiwi">Brown kiwi</a> <li><a href="#bushbaby">Bushbaby</a> <li><a href="#sequence_only">Bushbaby</a> (sequence only) <li><a href="#cat">Cat</a> <li><a href="#chimp">Chimpanzee</a> <li><a href="#chinese_hamster">Chinese hamster</a> <li><a href="#chinese_pangolin">Chinese pangolin</a> <li><a href="#cow">Cow</a> <li><a href="#crab-eating_macaque">Crab-eating_macaque</a> <div class="gbFooterCopyright"> &copy; 2017 The Regents of the University of California. All Rights Reserved. <br> <a href="https://genome.ucsc.edu/conditions.html">Conditions of Use</a> </div>' # 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