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

/
/
gm

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 = "(?P<error_date>^[\\w\\/\\.]+)\\s+(?P<error_time>[\\w\\/\\.\\:]+)\\s+\\*(?P<error_level>\\w+)\\*\\s+\\[((?P<error_ip>[\\d\\.]+)\\s+\\[(?P<error_thread_id>.+)\\]\\s+(?P<error_request_method>\\w+)\\s+(?P<error_urlpath>.+)\\s+(?P<error_req_protocol>.+)|(?P<error_thread>.+?))\\]\\s+(?P<error_message>.+[\\n]?.+)"; final String string = "\n" + "14.05.2021 11:52:20.598 *INFO* [oak-repository-executor-1] com.adobe.granite.repository Service [31211, [org.apache.jackrabbit.oak.api.jmx.SessionMBean]] ServiceEvent REGISTERED\n\n" + "14.05.2021 11:52:22.964 *WARN* [10.153.117.93 [1620993142877] GET /content/ewp-marketing-websites/legal/gl/en/c/prolaw-workspace.html HTTP/1.1] com.tr.emcm.slingmodels.EyeBrowDateModel Error while formatting date: \n" + "java.text.ParseException: Unparseable date: \"\"\n" + " at java.text.DateFormat.parse(DateFormat.java:366)\n" + " at com.tr.emcm.slingmodels.EyeBrowDateModel.setDate(EyeBrowDateModel.java:92)\n" + " at com.tr.emcm.slingmodels.EyeBrowDateModel.lambda$init$2(EyeBrowDateModel.java:72)\n" + "14.05.2021 11:52:22.972 *ERROR* [10.43.32.58 [1620993142925] GET /content/volvo/volvo-financial-services/markets/netherlands/nl-nl/home.html HTTP/1.1] com.volvo.platform.components.controllers.VolvoGroupStandardHeaderComponent RepositoryException Error occured while processing fetchExcelValues/content/volvo/volvo-financial-services/markets/netherlands/nl-nl/jcr:content/header\n" + "javax.jcr.AccessDeniedException: OakAccess0000: Access denied\n" + " at org.apache.jackrabbit.oak.api.CommitFailedException.asRepositoryException(CommitFailedException.java:232)\n" + " at org.apache.jackrabbit.oak.api.CommitFailedException.asRepositoryException(CommitFailedException.java:213)\n" + " at org.apache.jackrabbit.oak.jcr.delegate.SessionDelegate.newRepositoryException(SessionDelegate.java:669)\n" + "14.05.2021 11:52:22.980 *WARN* [10.105.105.19 [1620993142700] GET /content/onehub_nfz/de/de/angebote-und-finanzprodukte/gross-und-sonderkunden/kommunen-und-behoerden.dir.dir.dir.dir.dir.dir.dir.dir.dir.dir.dir.dir.html/__layer/layers/fahrzeugkauf/ansprechpartner-blaulichtfahrzeuge HTTP/1.1] org.apache.sling.caconfig.resource.impl.def.DefaultConfigurationResourceResolvingStrategy Ignoring reference to /conf/vwa-ngw18/settings from /conf/vwa-ngw18/settings - Probably misconfigured as it ends with '/settings'"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); 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