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
  • 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

/
/
gmx

Test String

Code Generator

Language

Generated Code

use strict; my $str = ''; my $regex = qr/(?(DEFINE) (?P<ver>\d+(?:\.\d+)*(?![.\d])) (?P<agent>Mozilla\/(?&ver)) (?P<os>(?&os_windows)|(?&os_linux)|(?&os_macintosh)|(?&os_ios)) (?P<os_windows>Windows[ ]\w+[ ](?&ver)) (?P<os_linux>Linux(?:[ ](?:i686|x86_64))?) (?P<os_macintosh>Macintosh) (?P<os_ios>(?:CPU[ ])?iPhone[ ]OS|CPU[ ]OS.*?like[ ]Mac[ ]OS[ ]X) (?P<device>(?&device_ios)|(?&device_firefox)|(?&device_android)) (?P<device_ios>iPhone|iPad) (?P<device_firefox>Mobile) (?P<device_android>Android(?:[ ](?&ver))?) (?P<browser> (?: (?&browser_ie) | (?&browser_safari) | (?&browser_chrome) | (?&browser_chromium) | (?&browser_firefox) | (?&browser_version) # | (?&browser_nexus) | (?&browser_mobile) | (?&browser_gsa) | (?&browser_quicklook) | (?&browser_opera) ) [ \/] (?: [A-Z\d]+\b(?!\.) | (?&ver) ) ) (?P<browser_safari>(?:Mobile[ ])?Safari) (?P<browser_chrome>Chrome) (?P<browser_chromium>\b\w+\b[ ]Chromium) (?P<browser_firefox>Firefox) (?P<browser_ie>MSIE) (?P<browser_version>Version) (?P<browser_nexus>Nexus[ ]\d+[ ]Build) (?P<browser_mobile>Mobile) (?P<browser_gsa>GSA) (?P<browser_quicklook>QuickLook) (?P<browser_opera>OPR) ) ^ (?:(?=.*?(?P<Agent>(?&agent)))) (?:(?=.*?(?P<OS>(?&os)))) (?:(?=.*?(?P<Device>(?&device))))? (?:(?=.*?(?P<Browser>(?&browser)(?:[ ](?&browser))*)))?/mxp; 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