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

/
/
g

Test String

Code Generator

Language

Generated Code

use strict; my $str = '<row Id="1394" PostTypeId="2" ParentId="1390" CreationDate="2008-08-04T16:38:03.667" Score="16" Body="&lt;p&gt;Not sure how credible &lt;a href=&quot;http://www.builderau.com.au/program/windows/soa/Getting-started-with-Windows-Server-2008-Core-edition/0,339024644,339288700,00.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this source is&lt;/a&gt;, but:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA; &lt;p&gt;The Windows Server 2008 Core edition can:&lt;/p&gt;&#xA; &#xA; &lt;ul&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the file server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the Hyper-V virtualization server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the Directory Services role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the DHCP server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the IIS Web server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the DNS server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run Active Directory Lightweight Directory Services.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run the print server role.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;/ul&gt;&#xA; &#xA; &lt;p&gt;The Windows Server 2008 Core edition cannot:&lt;/p&gt;&#xA; &#xA; &lt;ul&gt;&#xA; &lt;li&gt;&lt;p&gt;Run a SQL Server.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run an Exchange Server.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run Internet Explorer.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run Windows Explorer.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Host a remote desktop session.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;li&gt;&lt;p&gt;Run MMC snap-in consoles locally.&lt;/p&gt;&lt;/li&gt;&#xA; &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="91" LastEditorUserId="1" LastEditorDisplayName="Jeff Atwood" LastEditDate="2008-08-27T13:02:50.273" LastActivityDate="2008-08-27T13:02:50.273" CommentCount="1" /> '; my $regex = qr/^<row Id="([^"]*)" PostTypeId="([^"]*)" ParentId="([^"]*)" CreationDate="([^"]*)" Score="([^"]*)" Body="([^"]*)" OwnerUserId="([^"]*)" LastEditorUserId="([^"]*)" LastEditorDisplayName="([^"]*)" LastEditDate="([^"]*)" LastActivityDate="([^"]*)" CommentCount="([^"]*)"?.*$>/p; 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