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

/
/
mixg

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"(?(DEFINE) (?<tagnames> @CUSTOM-AT-1 | @CUSTOM-AT-2) (?<number> -? (?= [1-9]|0(?!\d) ) \d+ (\.\d+)? ([eE] [+-]? \d+)? ) (?<boolean> true | false | null ) (?<string> \"" ([^\""\\\\]* | \\\\ [\""\\\\bfnrt\/] | \\\\ u [0-9a-f]{4} )* \"" ) (?<array> \[ (?: (?&json) (?: , (?&json) )* )? \s* \] ) (?<pair> \s* (?&string) \s* : (?&json) ) (?<object> \{ (?: (?&pair) (?: , (?&pair) )* )? \s* \} ) (?<fieldname> [a-zA-Z0-9\_\-]+ ) (?<json> \s* (?: (?&number) | (?&boolean) | (?&string) | (?&array) | (?&object) ) ) (?<fieldlist> (?: (?&fieldname) (?: , (?&fieldname) )+ )+ ) ) (?<actiontag> (?&tagnames) ) (?:\= (?'params' (?: (?'match_list'(?&fieldlist)) | (?'match_json'(?&json)) | (?'match_string'(?:[[:alnum:]\_\-]+)) ) ) )"; string input = @"@FIELDLIST=field_1,field_2 @STRING=""Bar"" @JSON={""foo"":""bar""} @CUSTOM-AT-2={""strict"":true, ""targets"":[""field_3"", ""field_7""], ""title"":""Custom Title"", ""message"":""This is a custom message""} @CUSTOM-AT-1={""strict"":true, ""targets"":[""field_3"", ""field_7""], ""title"":""Custom Title"", ""message"":""This is a custom message""}"; RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace; 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