Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • 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

/
/
gm

Test String

Code Generator

Language

Generated Code

$re = '/^((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,}\.?((xn--)?([a-z0-9\-.]{1,61}|[a-z0-9-]{0,30})\.[a-z-1-9]{2,})$/m'; $str = '1c.ru 222.ru g.com 111.222.22.2 2.eu localhost 54.ru ya.ru www.pmmp.eiiil 129.0.0.100 127.0.0.1 22.22.22.220000 xn--b1aaa6i.xn--s1ak sub.mkyong-info.com mkyong.com.au g.co www.mk.mk.com www.pl.bluemedia-testserver.ts.twisto.wtf wwww.wwww.wwww.ww.w.wwww.www.ee https://regex101.com/r/sP0rLU/1/ foodemo.net bar.ba.test.co.uk www.demo.com http://foo.co.uk/ g.com g-.com com.g -g.com xn--d1ai6ai.xn--p1ai xn--fsqu00a.xn--com xn--stackoverflow.com stackoverflow.xn--com stackoverflow.co.uk google.com.au xn--b1aaaaaaaaaaaa96a.xn--b1aaaaaaaaaaaaa2vvc -0-0o.com a.net 0-0o.com 0-oz.co.uk 0-tension.com.br 0-wh-ao14-0.com-com.net a-1234567890-1234567890-1234567890-1234567890-1234567890-1234-z.eu.us a-1234567890-1234567890-1234567890-1234567890-1234567890-12345-z.eu.us (too long) List of valid domain names: www.google.com google.com mkyong123.com mkyong-info.com sub.mkyong.com sub.mkyong-info.com mkyong.com.au g.co mkyong.t.t.co List of invalid domain: mkyong.t.t.c mkyong,com '; preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0); // Print the entire match result var_dump($matches);

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 PHP, please visit: http://php.net/manual/en/ref.pcre.php