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

Substitution

Processing...

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"<ref\s+((?:group|follow|extends)\s*=(?:(?!name\s*=)[\s\S])*)?name\s*=\s*(?:""\s*([^""](?:(?!\s*\/>|\s*""\s*>|\s+(?:group|follow|extends)).)*?)\s*""|'\s*([^'""](?:(?!\s*\/>|\s*'>|\s+(?:group|follow|extends)).)*?)\s*'|([^""](?:(?!\s*\/>|\s*>|\s+(?:group|follow|extends)).)*))(\s+(?:group|follow|extends)\s*=(?:(?!\s*\/>|""\s*>|'\s*>)[\s\S])*)*\s*(?:(\/)|)>"; string substitution = @"<ref $1name=""$2$3$4""$5${6:+ /:}>"; string input = @"<ref name=Test1 /><ref name=Test2 /> <ref name=Bad 1 /><ref name=Bad 2 /> <ref name=""Test 3""/> <ref name=""Test 4"" /> <ref name=Test5>Foo</ref> <ref name=""Test 6"">Foo</ref> <ref name=Test7>Foo </ref> <ref name = Test8 > Foo </ref> <ref name = Test9 > Foo </ref> <ref name=""Test 10"">Foo </ref> <ref name = ""Test 11"" > Foo </ref> <ref name = Test12 > Foo </ref> <ref name = Test13 /> <ref name = ""Test 14"" /> <ref name = Test15 /> <ref name = ""Test 16"" /> <ref name = Test17 /> <ref name = ""Test 18"" /> <ref name=""Test/19"" /> ==A heading== <ref name = ""Test/20"" /> <ref name = ""Test 21""/> <ref name = ""Test / 22""/> <ref name = ""Test > 23""/> <ref name=""Te>st/ 23.1""/> <ref name ="" Test 24 ""/> <ref name='Test/ 25' /> <ref name='Test/ 26'> Foo </ref> <ref name='Te>st/ 27' /> <ref name = "" Test 28 "" >Foo</ref> <ref name='Test ""29""' /> - This one is expected to produce invalid XML ""'Test ""29""'""; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: ""'Test ""2 9""'"" <ref name = ""Test 30"" > <ref name = ""Test 31""> <ref name = ""Test 32"" /> <ref name = ""Test 33""/> <ref name = Test34 > <ref name = Test35> <ref name = Test36 /> <ref name = Test37/> <ref name = "" Test 38 ""/> <ref name = "" Test 39 "" /> <ref name='Test 40'/> <ref name=AAA/> <ref name=""BBB AAA BBB"" /> <ref name=""This ""isjustnot"" valid""/> - This one is expected to produce invalid XML ""This ""isjustnot"" valid""; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: ""This ""is just not"" valid"". <ref name=""This 'actually is' valid""/> <ref name='But this ""is also"" a problem' /> (or will be after our "" substitution) <ref name=apostrophe's /> <ref name=""more apostrophe's"" /> <ref name='this's bad, but we can fix it!' /> <ref name='this is okay'/> <ref name=""'this is dumb'""/> <ref name=""this is 'less' dumb"" /> <ref name=""what about 'this case'""/> <ref name=""'or this' one"" /> <ref name=""foo"" group=""bar""/> <ref name=""foo"" group=""bar"" /> <ref group=""bar"" name=""foo"" /> <ref name='foo' group='bar'/> <ref name='foo' group='bar' /> <ref group='bar' name='foo' /> <ref name=foo group=bar/> <ref name=foo group=bar /> <ref group=bar name=foo/> <ref name=""foo"" follow=""bar"" /> <ref name='foo' follow='bar'/> <ref name=foo follow=bar/> <ref name=""foo"" extends=""bar"" /> <ref name='foo' extends='bar'/> <ref name=foo extends=bar/> <ref name='foo' group=""bar"" extends=baz follow=""quux quux"" /> <ref group=""bar"" name='foo' extends=baz follow=""quux quux"" /> <ref group=""bar"" extends=baz name='foo' follow=""quux quux"" /> <ref group=""bar"" extends=baz follow=""quux quux"" name='foo' /> <ref group=""bar"" extends=baz name=foo follow=""quux quux"" /> <ref group=""bar"" extends=baz name=""foo's foo"" follow=""quux quux"" /> <ref group=""bar's > / bar"" extends=baz name='foos > / foo' follow=""quux quux"" /> <ref group= ""bar's > / bar"" extends= baz name= ' foos > / foo ' follow= ""quux > quux"" /> <ref name=""foos > / foo"" group=""bar's > / bar"" extends=baz follow=""quux quux""/> <ref name = ' foos > / foo ' group = ""bar's > / bar"" extends =baz follow ="" quux quux "" /> <ref name=""foos > / foo"" group=""bar's > / bar"" extends=baz follow='quux quux'/> "; RegexOptions options = RegexOptions.Multiline; Regex regex = new Regex(pattern, options); string result = regex.Replace(input, substitution); } }

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