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

/
/
gm

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'snake_case PascalCase 2PascalCase streamIOIO gREATERDtha modeADFAFdsADFads aBabcABCDabcABC modeADFdsADFads streamIO aBCabcABCabcA aBCabcA aabcABC deviceSNS pathASNs dscpCP awsVPC deviceID gREA1 gREAt gREAtREAt aABC modeADFsADFads modeADFads createAMode createBMode contextHTMLParser ibsReleaseTestVerificationRegressioNSuite hELLO camelCA camel01CC01 camelCa_1 aabc123 a ab abc abcd abcde camelCasecamelCasecamelCasecamelCasecamelCasecamelCase aG alphabet cP3 a1 a1G a123 camelCase lThan30DaysCount lessThan30DaysCount lessThan30DaysCountA greaterThan30LessThan60DaysCount greaterThan60LessThan90DaysCount greaterThan90DaysCount pascalCase pascal2Case pascalCaseA pascal2CaseA modeA mode2A mode2A2 mode2A2A madeEasy wonderFul andMe htmlParser h aaA camel01C camel01c01 camel01C01 camel0a1c1 camel0a1C1 camel0ac1b1C1 camelC camelC1 camelCa1 ibsReleaseTestVerificationRegressionSuite ibsReleaseTestVerificationRegressioN xmlHttpRequest newCustomerId innerStopwatch supportsIpv6OnIos youTubeImporter youtubeImporter affine3D'; my $regex = qr/^[a-z][a-z0-9]*(([A-Z][a-z0-9]+)*[A-Z]?|([a-z0-9]+[A-Z])*|[A-Z])$/mp; 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