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

/
/
gimx

Test String

Code Generator

Language

Generated Code

use strict; my $str = '{"menu": { "header": "SVG Viewer", "items": [ {"id": "Open"}, {"id": "OpenNew", "label": "Open New"}, null, {"id": "ZoomIn", "label": "Zoom In"}, {"id": "ZoomOut", "label": "Zoom Out"}, {"id": "OriginalView", "label": "Original View"}, null, {"id": "Quality"}, {"id": "Pause"}, {"id": "Mute"}, null, {"id": "Find", "label": "Find..."}, {"id": "FindAgain", "label": "Find Again"}, {"id": "Copy"}, {"id": "CopyAgain", "label": "Copy Again"}, {"id": "CopySVG", "label": "Copy SVG"}, {"id": "ViewSVG", "label": "View SVG"}, {"id": "ViewSource", "label": "View Source"}, {"id": "SaveAs", "label": "Save As"}, null, {"id": "Help"}, {"id": "About", "label": "About Adobe CVG Viewer..."} ], "test": [ "Some value", 4, null,{} ], "empty_array":[-0.34E+4] }}'; my $regex = qr/(?(DEFINE) (?<quote>['"]) (?<pair> (?> \w+ |(?: (?<pairQuote>(?&quote))[^'"]+?\k<pairQuote> ) ) \s*\: ) (?<string> (?<stringQuote>(?&quote))[\S\s]*?(?<!\\)\k<stringQuote> ) (?<integer>\-?\d+(?:\.\d+)?(?:e[-+]\d+)?) (?<scalar>true|false|null|(?&integer)) (?<elements> \s*(?&value) (?(R&array)|(?>(?:\s*\,(?&elements))|\s*)) ) (?<array>\[(?>(?&elements)|\s*)\]) (?<value> (?&object) |(?&string) |(?&scalar) |(?&array) ) (?<members> \s*(?&pair)\s*(?&value) (?(R&object)|(?>(?:\s*\,(?&members))|\s*)) ) (?<object>\{(?&members)?\}) ) \A(?&object)\Z/imxp; 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