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

/
/
m

Test String

Code Generator

Language

Generated Code

use strict; my $str = '## Simple recursive caching DNS, UDP port 53 ## unbound.conf -- https://calomel.org # server: access-control: 10.0.0.0/8 allow access-control: 127.0.0.0/8 allow access-control: 192.168.0.0/16 allow cache-max-ttl: 14400 cache-min-ttl: 900 hide-identity: yes hide-version: yes interface: 0.0.0.0 minimal-responses: yes prefetch: yes qname-minimisation: yes rrset-roundrobin: yes use-caps-for-id: yes verbosity: 1 forward-zone: name: "." forward-addr: 8.8.4.4 # Google forward-addr: 8.8.8.8 # Google forward-addr: 37.235.1.174 # FreeDNS forward-addr: 37.235.1.177 # FreeDNS forward-addr: 208.67.222.220 # OpenDNS forward-addr: 208.67.222.222 # OpenDNS forward-addr: 216.146.35.35 # Dyn Public forward-addr: 216.146.36.36 # Dyn Public forward-zone: name: "dns.com" forward-addr: 50.116.23.211 # OpenNIC forward-addr: 64.6.64.6 # Verisign forward-addr: 64.6.65.6 # Verisign forward-addr: 74.82.42.42 # Hurricane Electric forward-addr: 84.200.69.80 # DNS Watch forward-addr: 84.200.70.40 # DNS Watch forward-addr: 91.239.100.100 # censurfridns.dk forward-addr: 109.69.8.51 # puntCAT '; my $regex = qr/forward-zone:[.\s]*name:[\ ".\s]*forward/mp; if ( $str =~ /$regex/ ) { 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