Regular Expressions 101

Save & Share

  • Regex Version: ver. 3
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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

/
/
gmi

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 = "(^127\\.0\\.0\\.1[\\s]+|^0\\.0\\.0\\.0[\\s]+)([0-9a-z_.-]+$)|^([0-9a-z_.-]+$)"; final String string = "# hpHosts - FSA only\n" + "#\n" + "# The following are hosts in the hpHosts database with the FSA classification ONLY.\n" + "#\n" + "127.0.0.1 localhost #IPv4 localhost\n" + "127.0.0.1 localhost\n" + "::1 localhost #IPv6 localhost\n" + "#\n" + "# BAD SITES START HERE\n" + "#\n" + "0.0.0.0 very#badexample.com\n" + "very#badexample.com\n" + "domain@with.com\n" + "doma$in\n" + "AuThedMine.cOm\n" + "domain.0cf\n" + "127.0.0.1 0-0-----------------------------------------------------------0.com\n" + "127.0.0.1 0-google.com\n" + "127.0.0.1 00-lawyer.com\n" + "127.0.0.1 0000.support\n" + "0.01.2.13.3.sydneypropertyinvestors.com\n" + "0.01.2.23.3.sydneypropertyinvestors.com\n" + "000.9.009.09.ekurbani.com\n" + "000.9.019.09.ekurbani.com\n" + "000000-0.000webhostapp.com\n" + "00004563.000webhostapp.com\n" + "000m8ih.wcomhost.com\n" + "000m8n1.wcomhost.com\n" + "000m8pk.wcomhost.com\n" + "000m9w3.wcomhost.com\n" + "000macu.wcomhost.com\n" + "000magu.wcomhost.com\n" + "000map9.wcomhost.com\n" + "000may2.wcomhost.com\n" + "000mhl7.wcomhost.com\n" + "000mhpe.wcomhost.com\n" + "000mhpg.wcomhost.com\n" + "1xbet86.com\n" + "1xbet87.com\n" + "1xbet90.com\n" + "1xbet31.com\n" + "1xbet46.com\n" + "1xbet28.com\n" + "1xbet35.com\n" + "1xbet49.com\n" + "nejakyhost.cz\n" + "0.0.0.0 cnhv.co\n" + "0.0.0.0 coin-hive.com\n" + "0.0.0.0 coinhive.com\n" + "0.0.0.0 authedmine.com\n" + "0.0.0.0 api.jsecoin.com\n" + "0.0.0.0 load.jsecoin.com\n" + "0.0.0.0 server.jsecoin.com\n" + "0.0.0.0 miner.pr0gramm.com\n" + "0.0.0.0 minemytraffic.com\n" + "0.0.0.0 crypto-loot.com\n" + "0.0.0.0 cryptaloot.pro\n" + "0.0.0.0 cryptoloot.pro\n" + "0.0.0.0 coinerra.com\n" + "0.0.0.0 coin-have.com\n" + "0.0.0.0 minero.pw\n" + "0.0.0.0 minero-proxy-01.now.sh\n" + "0.0.0.0 minero-proxy-02.now.sh\n" + "0.0.0.0 minero-proxy-03.now.sh\n" + "0.0.0.0 api.inwemo.c\n" + "127.0.0.1 sfdfsdfsdfsdfsd\n" + "pool.pebblemedia.adhese.com"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | 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