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

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^([ \t]*)</head"; string input = @"<!DOCTYPE html><html class=""no-js"" lang=""es-ES""><head> <meta charset=""utf-8"" /> <meta name=""viewport"" content=""width=device-width, initial-scale=1.0"" /> <title></title> <meta name=""description"" content=""blog de programación""/> <meta property=""og:locale"" content=""es_ES"" /> <meta property=""og:type"" content=""website"" /> <meta property=""og:title"" content="" /> <meta property=""og:description"" content=""blog de programación"" /> <meta property=""og:url"" content="" /> <meta property=""og:site_name"" content="" /> <meta name=""robots"" content=""index, follow"" /> <!-- This site is being optimized with the Bob Bolt SEO Premium Extension™ v0.9.7 Platinum Edition Pro. --> </head><body><div class=""row"" id=""head""> <section id=""web""> </section></div> <script src=""/bolt-public/view/js/jquery-1.11.2.min.js""></script> <script src=""https://cdn.rawgit.com/google/code-prettify/master/loader/run_prettify.js?skin=sons-of-obsidian""></script><script type=""text/javascript"" src=""/js/main.1445862200.js""></script></body></html>"; RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnoreCase; Match m = Regex.Match(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