Regular Expressions 101

Save & Share

  • Regex Version: ver. 9
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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 = ' <li id="ctl00_LeftNavigation1_LeftMenu_ctl00_ListItem1" class="starLink"><a href=\'/CheatSheet.aspx\'>Regex Cheat Sheet</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl02_ListItem1"><a href=\'/Search.aspx\'>Search</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl03_ListItem1"><a href=\'/RETester.aspx\'>Regex Tester</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl04_ListItem1"><a href=\'/DisplayPatterns.aspx\'>Browse Expressions</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl05_ListItem1"><a href=\'/Add.aspx\'>Add Regex</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl06_ListItem1"><a href=\'/UserPatterns.aspx\'>Manage My Expressions</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl07_ListItem1"><a href=\'/Contributors.aspx\'>Contributors</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl11_ListItem1"><a href=\'/Resources.aspx\'>Regex Resources</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl12_ListItem1"><a href=\'/WebServices.asmx\'>Web Services</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl13_ListItem1"><a href=\'http://lakequincy.com/advertisers/publisherinfo/regExLib.aspx\'>Advertise</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl14_ListItem1"><a href=\'/Contact.aspx\'>Contact Us</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl15_ListItem1"><a href=\'/Register.aspx\'>Register</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl16_ListItem1" class="rssLink"><a href=\'http://feeds.feedburner.com/Regexlibcom-RecentPatterns\'>Recent Expressions</a></li> <li id="ctl00_LeftNavigation1_LeftMenu_ctl17_ListItem1" class="rssLink"><a href=\'http://feeds.feedburner.com/Regexlibcom-RecentComments\'>Recent Comments</a></li>'; my $regex = qr/<[^>]*>/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