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

r"
"
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

use strict; my $str = 'nospmiS maC retroper lanruoJ teertS llaW edulcni repapswen eht fo inmula elbatoN lmths .7665401-09.snruT .sweN-ehT/sweN/40/11/5002/swen/903repap/egarots/aidem/moc .swenned .www .aidem//:ptth .0891 ni nesohc saw eman tnerruc sti erofeb sweN etatS nretsaE dna sweN egelloC s\'rehcaeT demaner saw repap ehT .repapswen yliad a evah ot yrtnuoc eht ni seitisrevinu tsellams eht fo eno si dna 2999031 .1-sserp-lles-ot-setov-draob-aidem-tneduts/seirots-pot/moc .enilnonaxetyliad .www//:ptth sserp gnitnirp repapswen nwo sti nur ot setatS detinU eht ni seitisrevinu eerht ylno fo eno si ytisrevinU sionillI nretsaE'; my $regex = qr/(?=[a-zA-Z0-9\/ \.\-]+\/\/:ptth) \./mp; my $subst = '.'; my $result = $str =~ s/$regex/$subst/rg; print "The result of the substitution is' $result\n";

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