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

/
/
gi

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 = "(on|date)*\\s*\\,*(mon|tue|wed|thu|fri|sat)\\,*\\s*([0-9]{2,4}|([0-9]{2}:*){1,3})\\s+(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\\s+([0-9]{2,4}|([0-9]{2}:*){1,3})\\s+(([0-9]{2}:*){1,3}|[0-9]{2,4})\\s*((\\+|\\-)+(([0-9]{2}:*){1,3}|[0-9]{2,4}))*\n"; final String string = "From ilug-admin@linux.ie Wed Aug 21 13:33:23 2002\n" + "Return-Path: <ilug-admin@linux.ie>\n" + "Delivered-To: yyyy@localhost.netnoteinc.com\n" + "Received: from localhost (localhost [127.0.0.1])\n" + " by phobos.labs.netnoteinc.com (Postfix) with ESMTP id E0EBC43C34\n" + " for <jm@localhost>; Wed, 21 Aug 2002 08:33:21 -0400 (EDT)\n" + "Received: from phobos [127.0.0.1]\n" + " by localhost with IMAP (fetchmail-5.9.0)\n" + " for jm@localhost (single-drop); Wed, 21 Aug 2002 13:33:21 +0100 (IST)\n" + "Received: from lugh.tuatha.org (root@lugh.tuatha.org [194.125.145.45]) by\n" + " dogma.slashnull.org (8.11.6/8.11.6) with ESMTP id g7LCYUZ24675 for\n" + " <jm-ilug@jmason.org>; Wed, 21 Aug 2002 13:34:30 +0100\n" + "Received: from lugh (root@localhost [127.0.0.1]) by lugh.tuatha.org\n" + " (8.9.3/8.9.3) with ESMTP id NAA29496; Wed, 21 Aug 2002 13:33:16 +0100\n" + "X-Authentication-Warning: lugh.tuatha.org: Host root@localhost [127.0.0.1]\n" + " claimed to be lugh\n" + "Received: from salmon.maths.tcd.ie (mmdf@salmon.maths.tcd.ie\n" + " [134.226.81.11]) by lugh.tuatha.org (8.9.3/8.9.3) with SMTP id NAA29463\n" + " for <ilug@linux.ie>; Wed, 21 Aug 2002 13:33:07 +0100\n" + "Received: from walton.maths.tcd.ie by salmon.maths.tcd.ie with SMTP id\n" + " <aa96976@salmon>; 21 Aug 2002 13:33:06 +0100 (BST)\n" + "To: ilug@linux.ie\n" + "Subject: Re: [ILUG] URGENT: Cant get a skrew out... PLEASE HELP!\n" + "X-It'S: all good\n" + "X-Wigglefluff: fuddtastic\n" + "X-Zippy: When this load is DONE I think I'll wash it AGAIN..\n" + "In-Reply-To: Your message of\n" + " \"Wed, 21 Aug 2002 12:42:17 BST.\"\n" + " <BCEFLMCEIJHPCPLGADJICEDPCAAA.kialllists@redpie.com>\n" + "Date: Wed, 21 Aug 2002 13:33:06 +0100\n" + "From: Niall Brady <bradyn@maths.tcd.ie>\n" + "Message-Id: <200208211333.aa96976@salmon.maths.tcd.ie>\n" + "Sender: ilug-admin@linux.ie\n" + "Errors-To: ilug-admin@linux.ie\n" + "X-Mailman-Version: 1.1\n" + "Precedence: bulk\n" + "List-Id: Irish Linux Users' Group <ilug.linux.ie>\n" + "X-Beenthere: ilug@linux.ie\n\n" + "On Wed, 21 Aug 2002 12:42:17 BST, Kiall Mac Innes said:\n" + ">Hi i have a phillips head skrew thats holding a circut board together i need\n" + ">to take it out ASAP and nothing will work, the threads on the skrew are\n" + ">almost completly gone, its is a very small skrew that i have to use a\n" + ">percision skrewdriver set to remove the skrews any help would be\n" + ">appreaciated...\n\n" + "Get a very, *very* small set of drill bits. Start drilling right\n" + "through the center of the head, at a slow speed so you don't pop\n" + "off and through the board! Once you have a bit of an indent in,\n" + "increase the speed a little bit.\n\n" + "If you've made a deepish indent, and the head doesn't pop off, use\n" + "the next largest drill bit you have. Repeat until happy.\n\n" + "Eventually the head should just pop off, allowing you to lift the\n" + "board off over the shaft of the screw... then ye can take out the\n" + "rest fairly easily with a pliers or whatnot.\n\n" + "-- \n" + " Niall\n\n" + "-- \n" + "Irish Linux Users' Group: ilug@linux.ie\n" + "http://www.linux.ie/mailman/listinfo/ilug for (un)subscription information.\n" + "List maintainer: listmaster@linux.ie\n\n"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE); final Matcher matcher = pattern.matcher(string); while (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