Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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 = 'https://www.facebook.com/hung.le054 https://www.facebook.com/groups/j2team.community/?ref=nf_target&fref=nf&__xts__%5B0%5D=68.ARCufAkDYLfgBw09Ctl9HKUd8wMYIaATKYHE-9guWWpCGu86iH8k0p4Qx8BxlXEEJMW8shzzodIckx0qvnBg94kwMe3uOIPnjE9s6neoXwFX8kBJsWBpF-Ej8oXpGdiIu6sf9cg9tyeq&__tn__=C-R https://www.facebook.com/NoExit.GoEXID/?hc_ref=ARQCFBLI4l-ciKCPEGazrn4_8WTxAulTr9a7XgMTgi_OKA_Iad1-hMzdD2z0snaq3BE&fref=nf&__xts__%5B0%5D=68.ARAUlT1DqV2wkn3VWI7belmtRn5k9XXk05WUw1Gl88lm2CDjGSmYX0zI_p8A19EG2w6iWF3t0gZN-GurkpGl05KGdS5Xv8lC__sOmlxD8Jz5CrhOjbz1ThvYtiZA3yzk4P66-V5BjDty&__tn__=kCH-R https://www.facebook.com/profile.php?id=100010004806283&fref=pb&hc_location=friends_tab'; my $regex = qr/(?<=profile\.php\?id\=)(?<id>[0-9]+)|(?:(?<=\.com)|(?<=\.me)|(?<=\.co)|(?<=\.us))(?:(?:\/groups\/|\/)(?!profile\.php)(?<username>[\w\.\_]+))/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