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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

Substitution
Processing...

Code Generator

Language

Generated Code

import re regex = re.compile(r"^(?:(?: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*$", flags=re.MULTILINE) test_str = (" various protocols (and lack of one):\n" "https://www.youtube.com/watch?v=U9t-slLl30E\n" "http://www.youtube.com/watch?v=U9t-slLl30E\n" "//www.youtube.com/watch?v=U9t-slLl30E\n" "www.youtube.com/watch?v=U9t-slLl30E\n\n" " and for each protocol\n" " various domains:\n" "www.youtube.com/watch?v=U9t-slLl30E\n" "m.youtube.com/watch?v=U9t-slLl30E\n" "music.youtube.com/watch?v=OD3F7J2PeYU\n" "youtube.com/watch?v=U9t-slLl30E\n" "www.youtube-nocookie.com/embed/U9t-slLl30E\n" "youtu.be/U9t-slLl30E\n\n" " and for each domain (despite -nocookie)\n" " various paths:\n" "youtube.com/watch?v=U9t-slLl30E\n" "youtube.com/watch/U9t-slLl30E\n" "youtube.com/v/U9t-slLl30E\n" "youtube.com/embed/U9t-slLl30E\n" "youtube.com/e/U9t-slLl30E\n" "youtube.com/live/9UMxZofMNbA\n" "youtube.com/shorts/gOcxEMJSksg\n" "youtube.com/oembed?url=http%3A//www.youtube.com/watch?v%3DU9t-slLl30E&format=json\n" "youtube.com/attribution_link?a=JdfC0C9V6ZI&u=%2Fwatch%3Fv%3DU9t-slLl30E%26feature%3Dshare\n" "youtube.com/attribution_link?a=8g8kPrPIi-ecwIsS&u=/watch%3Fv%3DU9t-slLl30E%26feature%3Dem-uploademail\n\n" " and for each path\n" " various parameters:\n" "youtube.com/watch?v=U9t-slLl30E\n" "youtube.com/watch?v=U9t-slLl30E&feature=shared\n" "youtube.com/watch?v=U9t-slLl30E&t=1m02s\n" "youtube.com/watch?v=U9t-slLl30E&lc=UgyYsn3aIQWSA19Esi54AaABAg\n" "youtube.com/watch?v=Lo2qQmj0_h4&list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t&index=5&pp=iAQB8AUB\n" " in various order:\n" "youtube.com/watch?feature=shared&v=U9t-slLl30E\n\n" " but not these:\n" "(wrong ID)\n" "youtube.com/watch?v=U$t-slLl30E\n" "(too short ID)\n" "youtube.com/watch?v=U9t-slLl30&t=10\n" "(wrong or deprecated paths)\n" "youtube.com/GitHub?v=U9t-slLl30E\n" "youtube.com/?v=U9t-slLl30E\n" "youtube.com/?vi=U9t-slLl30E\n" "youtube.com/?feature=player_embedded&v=U9t-slLl30E\n" "youtube.com/watch?vi=U9t-slLl30E\n" "youtube.com/vi/U9t-slLl30E\n" "(www.youtube-nocookie.com/embed/ only!)\n" "youtube-nocookie.com/embed/U9t-slLl30E\n" "www.youtube-nocookie.com/watch?v=U9t-slLl30E\n" "http://www.youtube-nocookie.com/v/U9t-slLl30E?version=3&hl=en_US&rel=0\n" "(playlist)\n" "youtube.com/playlist?list=PLmXxqSJJq-yVWpRFGImHYZBQTuBGLjG4t") subst = "https://www.youtube.com/watch?v=XGkm-6yCIio" result = regex.sub(subst, test_str) if result: print(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 Python, please visit: https://docs.python.org/3/library/re.html