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 = 'from s32.hekko.net.com by s32.hekko.net.com with LMTP id 0KRkJkxRu1qDS1AAbRxtZA for <john@gmail.com>; Wed, 28 Mar 2018 10:24:44 +0200 Return-path: <johnsfather@onet.com> Envelope-to: john@gmail.com Delivery-date: Wed, 28 Mar 2018 10:24:44 +0200 from smtpo114.poczta.onet.com ([213.180.149.147]) by s32.hekko.net.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from <johnsfather@onet.com>) id 1f16Nv-00057D-Sj for john@gmail.com; Wed, 28 Mar 2018 10:24:44 +0200 from pmq4v.m5r2.onet (pmq4v.m5r2.onet [30.174.32.60]) by smtp.poczta.onet.com (Onet) with ESMTP id 40B2Bw16y9zqtBg4 for <john@gmail.com>; Wed, 28 Mar 2018 10:24:40 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=onet.com; s=2011; t=1522235480; bh=6YEU3a1jv48GQ33zI1zre2Sf05w2DqLyMQhJ7UmYfyM=; h=From:To:Date:Subject:From; b=svf7rTDJFp7gUMQFA6GShG07bYFIpsSaxPOvdXYad/2ln6x+BGE4z4OoIfqBgpGhE 2n43jucpTRvw7mdT33vor7NXnI6mMXjLZjJp6J4cOpxGLnuAnSEo0G/xLWirIgFmm4 TojYv7tx5z/PugqZc/c59WzApn14FEhmVSrC+1IE= Content-Type: multipart/alternative; boundary="===============2073168411==" MIME-Version: 1.0 from [37.47.10.237] by pma4v.m5r2.onet via HTTP id 201803281024458192010001; Wed, 28 Mar 2018 10:24:40 +0200'; my $regex = qr/(by ).*(with)/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