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

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"<li><a href=\""(?:(?!#sequence_only).)*\"">(.*)</a>"; string input = @" <!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>"; RegexOptions options = RegexOptions.Multiline; foreach (Match m in Regex.Matches(input, pattern, options)) { Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index); } } }

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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx