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

/
/
gmx

Test String

Code Generator

Language

Generated Code

use strict; my $str = '0.0.0.0 00.00.00.00 000.000.000.000 1.2.3.4 01.02.03.04 001.002.003.004 11.22.3.44 11.22.03.44 011.022.033.044 23.34.34.5 23.34.34.05 123.234.034.005 1.1.192.168 01.01.192.168 001.001.192.168 text 123.234.34.123 more text text123.234.34.123more text 1.2.3.255 1.2.3.256 255.255.255.255 256.2.3.4 1123.234.34.123 123.234.34.1235 .123.234.34.123 123.234.34.123. not 1.1.168.192 in 1.1.168.192.in-addr.arpa. not 1.14.2.90 in xserver-common_1.14.2.901-2_all.deb 1.2.3.4'; my $regex = qr/\b # Leading marker (?P<byte> # Define a full byte 25[012345] | # the numers 250 - 255 or 2[01234](?P<digit>[0123456789]) | # 200 - 249 or 1(?&digit){2} | # 100 - 199 or #0? # Allow leading zero [1-9](?&digit) | # 10 - 99 or #0{0,2} # Allow leading zeros (?&digit) # 0 - 9 ) # close one full byte (\.(?&byte)){3} # Repeat three more bytes. \b # Trailing marker/mxp; 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