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

~
~
mg

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'youtube.com/watch?v=DFYRQ_zQ-gk www.youtube.com/watch?v=DFYRQ_zQ-gk https://youtube.com/watch?v=DFYRQ_zQ-gk https://www.youtube.com/watch?v=DFYRQ_zQ-gk https://www.youtube.com/watch?v=DFYRQ_zQ-gk&feature=feedrec_grec_index https://www.youtube.com/watch?v=DFYRQ_zQ-gk#t=0m10s https://www.youtube.com/?feature=player_embedded&v=DFYRQ_zQ-gk https://www.youtube.com/watch?feature=player_embedded&v=DFYRQ_zQ-gk https://www.youtube.com/UCucW7UIJh8FHbv2O0jW8skw?v=DFYRQ_zQ-gk#t=0m10s https://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&amp;hl=en_US&amp;rel=0 https://www.youtube.com/e/DFYRQ_zQ-gk?fs=1&amp;hl=en_US&amp;rel=0 https://www.youtube.com/embed/DFYRQ_zQ-gk?rel=0 https://www.youtube.com/user/UCucW7UIJh8FHbv2O0jW8skw#p/u/11/DFYRQ_zQ-gk?rel=0 https://www.youtube.com/UCucW7UIJh8FHbv2O0jW8skw#p/c/54B8C800269D7C1B/0/DFYRQ_zQ-gk?rel=0 m.youtube.com/watch?v=DFYRQ_zQ-gk //m.youtube.com/watch?v=DFYRQ_zQ-gk https://m.youtube.com/watch?v=DFYRQ_zQ-gk youtu.be/DFYRQ_zQ-gk https://youtu.be/DFYRQ_zQ-gk https://youtu.be/DFYRQ_zQ-gk?t=2s https://youtu.be/DFYRQ_zQ-gk?list=PLelYX5BVrtO0sWvnTSdvot21pjlKTNVeU https://youtube-nocookie.com/watch?v=DFYRQ_zQ-gk?t=2s <iframe width="480" height="270" src="https://www.youtube.com/embed/DFYRQ_zQ-gk?feature=oembed" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> in text youtube.com/watch?v=DFYRQ_zQ-gk in text DFYRQ_zQ-gk /watch?v=DFYRQ_zQ-gk https://www.youtubee.com/watch?v=DFYRQ_zQ-gk https://notyoutube.com/watch?v=DFYRQ_zQ-gk '; my $regex = qr~(?:^|\W)(?:youtube(?:-nocookie)?\.com/(?:.*[?&]v=|v/|e(?:mbed)?/|[^/]+/.+/)|youtu\.be/)([\w-]+)~mp; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

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 Perl, please visit: http://perldoc.perl.org/perlre.html