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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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 = 'Correct: 01/01/2000 01/Jan/2000 31/01/2000 31/Jan/2000 31.Jan.2000 31-Jan-2000 01/1/2000 x form 01/Jan/2000 01/1/01 x form 01/Jan/01 29/02/2000 x date 29/Feb/2000 28/02/2001 28/Feb/2001 30/04/2000 30/Apr/2000 31/07/2000 31/Jul/2000 31/08/2000 31/Aug/2000 01/12/2000 01/Dec/2000 31-01-8888 ? 02/Jan-1984 1.1.0 x form 10.11.12 all catched as x form 0,0,0 test 31.100.1952 32/03/18 1.2.3 123.2.12 _22.02.18_ 22-02-18test 22/02-18 22//02/18 22 02-18 22:02:18 1,2,3 False: 32/01/2000 x form 32/Jan/2000 01/15/2000 x form 29/02/2001 x date 29/Feb/2001 29/02/1900 x date 31/04/2000 x date 31/Apr/2000 31/09/2000 x date 31/Sep/2000 1.2.3-4 1-2-3.4 10.10.10.10 2w4w6 ... falls on the date of 10.11.12. ... it.10.11.12 has some type - there should be a whitespace but ....'; my $regex = qr/(?<!\d[- \/.])(?<!\d)(3[01]|[12][0-9]|0?[1-9])[- \/.](1[012]|0?[1-9])[- \/.](?:\d{2})?(\d?\d)(?![- \/.]?\d)/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