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

Substitution

Processing...

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^(?:(?:https?:)?\/\/)?(?:(?:(?:www|m(?:usic)?)\.)?youtu(?:\.be|be\.com)\/(?:shorts\/|live\/|v\/|e(?:mbed)?\/|watch(?:\/|\?(?:\S+=\S+&)*v=)|oembed\?url=https?%3A\/\/(?:www|m(?:usic)?)\.youtube\.com\/watch\?(?:\S+=\S+&)*v%3D|attribution_link\?(?:\S+=\S+&)*u=(?:\/|%2F)watch(?:\?|%3F)v(?:=|%3D))?|www\.youtube-nocookie\.com\/embed\/)([\w-]{11})[\?&#]?\S*$"; string substitution = @"https://www.youtube.com/watch?v=XGkm-6yCIio"; string input = @" various protocols (and lack of one): https://www.youtube.com/watch?v=U9t-slLl30E http://www.youtube.com/watch?v=U9t-slLl30E //www.youtube.com/watch?v=U9t-slLl30E www.youtube.com/watch?v=U9t-slLl30E and for each protocol various domains: www.youtube.com/watch?v=U9t-slLl30E m.youtube.com/watch?v=U9t-slLl30E music.youtube.com/watch?v=OD3F7J2PeYU youtube.com/watch?v=U9t-slLl30E www.youtube-nocookie.com/embed/U9t-slLl30E youtu.be/U9t-slLl30E and for each domain (despite -nocookie) various paths: youtube.com/watch?v=U9t-slLl30E youtube.com/watch/U9t-slLl30E youtube.com/v/U9t-slLl30E youtube.com/embed/U9t-slLl30E youtube.com/e/U9t-slLl30E youtube.com/live/9UMxZofMNbA youtube.com/shorts/gOcxEMJSksg youtube.com/oembed?url=http%3A//www.youtube.com/watch?v%3DU9t-slLl30E&format=json youtube.com/attribution_link?a=JdfC0C9V6ZI&u=%2Fwatch%3Fv%3DU9t-slLl30E%26feature%3Dshare youtube.com/attribution_link?a=8g8kPrPIi-ecwIsS&u=/watch%3Fv%3DU9t-slLl30E%26feature%3Dem-uploademail and for each path various parameters: youtube.com/watch?v=U9t-slLl30E youtube.com/watch?v=U9t-slLl30E&feature=shared youtube.com/watch?v=U9t-slLl30E&t=1m02s youtube.com/watch?v=U9t-slLl30E&lc=UgyYsn3aIQWSA19Esi54AaABAg youtube.com/watch?v=Lo2qQmj0_h4&list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t&index=5&pp=iAQB8AUB in various order: youtube.com/watch?feature=shared&v=U9t-slLl30E but not these: (wrong ID) youtube.com/watch?v=U$t-slLl30E (too short ID) youtube.com/watch?v=U9t-slLl30&t=10 (wrong or deprecated paths) youtube.com/GitHub?v=U9t-slLl30E youtube.com/?v=U9t-slLl30E youtube.com/?vi=U9t-slLl30E youtube.com/?feature=player_embedded&v=U9t-slLl30E youtube.com/watch?vi=U9t-slLl30E youtube.com/vi/U9t-slLl30E (www.youtube-nocookie.com/embed/ only!) youtube-nocookie.com/embed/U9t-slLl30E www.youtube-nocookie.com/watch?v=U9t-slLl30E http://www.youtube-nocookie.com/v/U9t-slLl30E?version=3&hl=en_US&rel=0 (playlist) youtube.com/playlist?list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t"; 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