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

r"
"

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'From: <email@example.com> FROM name fails Closed (fixed) Project: SMTP Authentication Support Version: 6.x-1.0-beta5 Component: Code Priority: Normal Category: Bug report Assigned: José San Martin Reporter: goose2000 Created: July 8, 2008 - 12:54 Updated: October 5, 2012 - 19:01 Log in or register to update this issue Jump to: Most recent attachment Hi, my development site is running on IIS with SMTP server. Mail is working fine when creating new users or getting a password reset. I have built a webform and upon submitting I\'ll get this error: * warning: mail() [function.mail]: SMTP server response: 501 5.5.4 Invalid Address in C:\\Inetpub\\wwwroot\\BHI_dev\\includes\\mail.inc on line 193. * Unable to send e-mail. Please contact the site admin, if the problem persists. The address I use in my testing are in fact completely valid. Seems like webform is not playing nice with the core somehow. Further ideas? Using Drupal 6.2. Thanks. Files: Comment File Size Author #25 smtp_279836.patch 694 bytes scttnlsn #13 smtp_module_name_patch_279836_01.patch 724 bytes franz #6 smtp_module_name_patch_279836_01.patch 724 bytes rfay Comments goose2000’s picture Comment #1goose2000 CreditAttribution: goose2000 commented 8 years ago Priority: Critical » Minor This seems to be an IIS SMTP issue only. See here: http://drupal.org/node/33967 Easy work around is to have no \'name\' text , just the email address when you configure webform. Think it may still be fixable at the code? I set it to \'minor\' now. Working great, one of the best modules around. Log in or register to post comments quicksketch’s picture Comment #2quicksketch CreditAttribution: quicksketch commented 7 years ago Title: Email Invalid Address » "Name" <email@example.com> FROM name fails Project: Webform » SMTP Authentication Support Version: 6.x-2.1.1 » 6.x-1.0-beta3 Moving to the SMTP module. To summarize, Webform users have not been able to send e-mails when using the SMTP module and the FROM e-mail addresses are formatted as "First Last" <email@example.com>. The name is properly mime_header_encoded when necessary. Any users experiencing this issue, please update with the version of SMTP module you\'re using.'; my $regex = qr/.*@(\S+)/p; if ( $str =~ /$regex/ ) { 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