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

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = ".*@(\\S+)"; final String string = "From: <email@example.com> FROM name fails\n\n" + "Closed (fixed)\n" + "Project: \n" + "SMTP Authentication Support\n" + "Version: \n" + "6.x-1.0-beta5\n" + "Component: \n" + "Code\n" + "Priority: \n" + "Normal\n" + "Category: \n" + "Bug report\n" + "Assigned: \n" + "José San Martin\n" + "Reporter: \n" + "goose2000\n" + "Created: \n" + "July 8, 2008 - 12:54\n" + "Updated: \n" + "October 5, 2012 - 19:01\n" + "Log in or register to update this issue\n" + "Jump to:\n" + "Most recent attachment\n" + "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:\n\n\n" + " * 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.\n" + " * Unable to send e-mail. Please contact the site admin, if the problem persists.\n\n" + "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?\n\n" + "Using Drupal 6.2.\n\n" + "Thanks.\n\n" + "Files: \n" + "Comment File Size Author\n" + "#25 smtp_279836.patch 694 bytes scttnlsn\n" + "#13 smtp_module_name_patch_279836_01.patch 724 bytes franz\n" + "#6 smtp_module_name_patch_279836_01.patch 724 bytes rfay\n" + "Comments\n" + " goose2000’s picture\n" + "Comment #1goose2000 CreditAttribution: goose2000 commented 8 years ago\n" + "Priority: Critical » Minor\n" + "This seems to be an IIS SMTP issue only. See here:\n\n" + "http://drupal.org/node/33967\n\n" + "Easy work around is to have no 'name' text , just the email address when you configure webform.\n" + "Think it may still be fixable at the code? I set it to 'minor' now.\n\n" + "Working great, one of the best modules around.\n" + "Log in or register to post comments\n" + " quicksketch’s picture\n" + "Comment #2quicksketch CreditAttribution: quicksketch commented 7 years ago\n" + "Title: Email Invalid Address » \"Name\" <email@example.com> FROM name fails\n" + "Project: Webform » SMTP Authentication Support\n" + "Version: 6.x-2.1.1 » 6.x-1.0-beta3\n" + "Moving to the SMTP module.\n\n" + "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.\n\n" + "Any users experiencing this issue, please update with the version of SMTP module you're using."; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html