Regular Expressions 101

Save & Manage Regex

  • Current Version: 3
  • Save & Share
  • Community Library

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
Sponsors
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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"Authentication-results:.+?sender IP.+\R?.+?mailfrom=(.+?);", flags=re.UNICODE) test_str = ("Return-path: <JaneSmith@SomeDummyCo.com>\n" "Received: from ms11p00im-qufv17093501.mac.com ([17.58.36.64])\n" " by ms24534.mac.com\n" " (Oracle Communications Messaging Server 8.0.1.3.20170906 64bit (built Sep 6\n" " 2017)) with ESMTP id <0PE4008Z5RC0PLA0@ms24534.mac.com> for\n" " JohnDoe@icloud.com; Mon, 27 Aug 2018 17:31:12 +0000 (GMT)\n" "Original-recipient: rfc822;JohnDoe@icloud.com\n" "Received: from NAM04-SN1-obe.outbound.protection.outlook.com\n" " (mail-eopbgr700137.outbound.protection.outlook.com [40.107.70.137])\n" " by ms11p00im-qufv17093501.me.com\n" " (Oracle Communications Messaging Server 8.0.2.2.20180531 64bit (built May 31\n" " 2018)) with ESMTPS id <0PE400K2IRBZ4F00@ms11p00im-qufv17093501.me.com> for\n" " JohnDoe@icloud.com (ORCPT JohnDoe@icloud.com); Mon,\n" " 27 Aug 2018 17:31:12 +0000 (GMT)\n" "X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0\n" " clxscore=1005 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0\n" " bulkscore=0 classifier=clx:Deliver adjust=0 reason=mlx scancount=1\n" " engine=8.0.1-1807170000 definitions=main-1808270184\n" "X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,,\n" " definitions=2018-08-27_07:,, signatures=0\n" "Authentication-results: ms11p00im-qufv10093201.me.com; dmarc=none\n" " header.from=apoemail.us\n" "Authentication-results: ms11p00im-qufv10113901.me.com; spf=pass\n" " (ms11p00im-qufv10113901.me.com: domain of JaneSmith@SomeDummyCo.com designates\n" " 40.107.70.137 as permitted sender) smtp.mailfrom=JaneSmith@SomeDummyCo.com\n" "Received-SPF: pass (ms11p00im-qufv10113901.me.com: domain of\n" " JaneSmith@SomeDummyCo.com designates 40.107.70.137 as permitted sender)\n" " receiver=ms11p00im-qufv10113901.me.com; client-ip=40.107.70.137;\n" " helo=NAM04-SN1-obe.outbound.protection.outlook.com;\n" " envelope-from=JaneSmith@SomeDummyCo.com\n" "Authentication-results: ms11p00im-qufv17063001.me.com; dkim=pass (1024-bit key)\n" " header.d=NETORGFT744019.onmicrosoft.com\n" " header.i=@NETORGFT744019.onmicrosoft.com header.b=fYoFciKN\n" "DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;\n" " d=NETORGFT744019.onmicrosoft.com; s=selector1-apoemail-us;\n" " h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;\n" " bh=ZUfrOM+P5LAWsuKD/Lnb58GuE4orISbImwlBF3a/vyc=;\n" " b=fYoFciKNtylrXwhibBhDmgiw70cFEaUP4XADRpc2cfX3M/4o94Uc7kMGMdo7wj1KqH/d/ShRSn1YX36qzEnW5yA26XIloXj/bt7iZX2LN5boJlI6OaE6DFUIKivm2Cfvl4Q9wckPQRot76ogx/NeYCwfJvD/OgGybwJWjoLQQJo=\n" "Received: from DM3PR19MB0521.namprd19.prod.outlook.com (10.164.248.145)\n" " by DM3PR19MB0825.namprd19.prod.outlook.com (10.166.164.151)\n" " with Microsoft SMTP Server\n" " (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384)\n" " id 15.20.1080.14; Mon, 27 Aug 2018 17:31:09 +0000\n" "Received: from DM3PR19MB0521.namprd19.prod.outlook.com\n" " ([fe80::69c8:8da3:dc38:8caa]) by DM3PR19MB0521.namprd19.prod.outlook.com\n" " ([fe80::69c8:8da3:dc38:8caa%5]) with mapi id 15.20.1080.015; Mon,\n" " 27 Aug 2018 17:31:09 +0000\n" "From: John Doe <JaneSmith@SomeDummyCo.com>\n" "To: John Doe <JohnDoe@icloud.com>\n" "Subject: AutoResponder - Acme Inc - New Client Questionnaire - - Steven\n" " Plain Text TEST 03/12/1971\n" "Thread-topic: AutoResponder - Acme Inc - New Client Questionnaire - -\n" " Steven Plain Text TEST 03/12/1971\n" "Thread-index: AQHUPiu+8RdF6Tdpg0SO88Zlg/iLzQ==\n" "Date: Mon, 27 Aug 2018 17:31:09 +0000\n" "Message-id: <D7A99F58.1E1AA%JaneSmith@SomeDummyCo.com>\n" "Accept-Language: en-US\n" "Content-language: en-US\n" "X-MS-Has-Attach:\n" "Authentication-results: spf=none (sender IP is )\n" " smtp.mailfrom=JaneSmith@SomeDummyCo.com;\n" "X-Originating-IP: [98.195.128.79]\n" "X-Microsoft-Exchange-Diagnostics:\n") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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 Python, please visit: https://docs.python.org/3/library/re.html