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

re = /^(?:(?: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*$/m str = ' various protocols (and lack of one): https://www.youtube.com/watch?v=U9t-slLl30E http://www.youtube.com/watch?v=U9t-slLl30E //www.youtube.com/watch?v=U9t-slLl30E www.youtube.com/watch?v=U9t-slLl30E and for each protocol various domains: www.youtube.com/watch?v=U9t-slLl30E m.youtube.com/watch?v=U9t-slLl30E music.youtube.com/watch?v=OD3F7J2PeYU youtube.com/watch?v=U9t-slLl30E www.youtube-nocookie.com/embed/U9t-slLl30E youtu.be/U9t-slLl30E and for each domain (despite -nocookie) various paths: youtube.com/watch?v=U9t-slLl30E youtube.com/watch/U9t-slLl30E youtube.com/v/U9t-slLl30E youtube.com/embed/U9t-slLl30E youtube.com/e/U9t-slLl30E youtube.com/live/9UMxZofMNbA youtube.com/shorts/gOcxEMJSksg youtube.com/oembed?url=http%3A//www.youtube.com/watch?v%3DU9t-slLl30E&format=json youtube.com/attribution_link?a=JdfC0C9V6ZI&u=%2Fwatch%3Fv%3DU9t-slLl30E%26feature%3Dshare youtube.com/attribution_link?a=8g8kPrPIi-ecwIsS&u=/watch%3Fv%3DU9t-slLl30E%26feature%3Dem-uploademail and for each path various parameters: youtube.com/watch?v=U9t-slLl30E youtube.com/watch?v=U9t-slLl30E&feature=shared youtube.com/watch?v=U9t-slLl30E&t=1m02s youtube.com/watch?v=U9t-slLl30E&lc=UgyYsn3aIQWSA19Esi54AaABAg youtube.com/watch?v=Lo2qQmj0_h4&list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t&index=5&pp=iAQB8AUB in various order: youtube.com/watch?feature=shared&v=U9t-slLl30E but not these: (wrong ID) youtube.com/watch?v=U$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' subst = 'https://www.youtube.com/watch?v=XGkm-6yCIio' result = str.gsub(re, subst) # Print the result of the substitution puts result

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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html