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

/
/
g

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'Lines which should be partially or fully matched: http:www.google.com/ http//www.google.com/ http://www.google.com/ ://www.google.com/ www.google.com/ www.google.com:8000 www.google.com/?key=value github.io www.google.com/abc/def/ijk#123 www.google.com/abc/def/ijk?v=123123123 www.google.com/abc/def/watch?v=1231231231 https://www.youtube.com/channel/UCgeu2xe0XRscaKyvBt3WgmQ http://www.google.com/?key=value http://www.youtube.com/ However, it should skip (do not match lines) which contain youtube video ID): http://www.youtube.com/watch?v=B5Gj78s6H7w&feature=youtu.be https://www.youtube.com/embed/y19EaW2X7ac music.youtube.com/embed/y19EaW2X7ac https://www.youtube.com/watch?v=B5Gj78s6H7w&feature=youtu.be https://www.youtube.com/watch?feature=youtu.be&v=B5Gj78s6H7w https://www.youtu.be/B5Gj78s6H7w&feature=youtu.be https://www.youtu.be/B5Gj78s6H7w '; my $regex = qr/(?i)(?(DEFINE)(?<proto>(?:https?:)?\/\/)(?<port>:[0-9]{2,5})(?<tld>(?:a(?:[cd]|e(?:ro)?|[fgil-oqr]|s(?:ia)?|[tuwxz])|b(?:[abd-h]|iz?|[jl-oq-tvwyz])|c(?:at?|[cdf-ik-n]|o(?:m|op)?|[ru-z])|d[ejkmoz]|e[ceghr-u]|f[i-kmor]|g[abd-il-np-uwy]|h[kmnrtu]|i(?:[delm]|n(?:fo|t)?|[oq-t])|j(?:[em]|o(?:bs)?|p)|k[eg-imnprwyz]|l[a-cikr-vy]|m(?:[ac-hk]|lc?|[mn]|o(?:bi)?|[p-t]|u(?:seum)?|[v-z])|n(?:a(?:me)?|c|et?|[fgilopruz])|o(?:m|rg)|p(?:[ae-hk-n]|ost|ro?|[stwy])|qa|r[eosuw]|s(?:[a-eg-or]|t(?:udio)?|[uvx-z])|t(?:[cd]|el|[f-hj-p]|r(?:avel)?|[tvwz])|u[agkmsyz]|v[aceginu]|w[fs]|y[et]|z[amw]))(?<path>(\/(?:[a-z0-9+%-]\.?)+)*\/?)(?<query>\?[a-z+&$_.-][a-z0-9;:@&%=+\/.-]*)(?<hash>\#[a-z_.-][a-z0-9+$%_.-]*)(?<subdomain>[a-z0-9\-\.]+\.)(?<yt_domain>(?:www\.)?(?:youtube\.com|youtu\.be)\/)(?<yt_hash>(?:[\w-]{10,12})+)(?<yt_video>(?&proto)?(?&yt_domain)+(?:watch)?(?:\/embed\/|\?v=)+(?&yt_hash)+))((?&yt_video).*(*SKIP)(*FAIL)|(?&proto)?(?&subdomain)(?&tld)(?&port)?(?&path)?(?&query)?(?&hash)?)/p; 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