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

/
/
umg

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{L}\\p{M}\\p{N}!#$%&'*+/=?^`\\{|\\}~-]|[\\p{L}\\p{M}\\p{N}!#$%&'*+/=?^`\\{|\\}~-](?:[\\p{L}\\p{M}\\p{N}!#$%&'*+/=?^`\\{|\\}~-]|\\.(?!\\.)){0,62}[\\p{L}\\p{M}\\p{N}!#$%&'*+/=?^`\\{|\\}~-])@(?:[\\p{L}\\p{M}\\p{N}]|[\\p{L}\\p{M}\\p{N}][\\p{L}\\p{M}\\p{N}_-]{0,61}[\\p{L}\\p{M}\\p{N}])(?:\\.(?:[\\p{L}\\p{M}\\p{N}]|[\\p{L}\\p{M}\\p{N}][\\p{L}\\p{M}\\p{N}_-]{0,61}[\\p{L}\\p{M}\\p{N}]))+\\.?$"; final String string = "VALID_SUPPORTED\n\n" + "-hello@world.co\n" + "hello.world@co.co\n" + "simple@example.com\n" + "underscore@in_domain.net\n" + "simple@example.com.\n" + "very.common@example.com\n" + "संपर्क@डाटामेल.भारत\n" + "disposable.style.email.with+symbol@example.com\n" + "медведь@с-балалайкой.рф\n" + "other.email-with-hyphen@example.com\n" + "fully-qualified-domain@example.com.\n" + "user.name+tag+sorting@example.com\n" + "Pelé@example.com\n" + "x@example.com\n" + "example-indeed@strange-example.com\n" + "test/test@test.com\n" + "böb@example.com\n" + "BÖB@gmail.com\n" + "example@s.example\n" + "mailhost!username@example.org\n" + "user%example.com@example.org\n" + "user-@example.org\n" + "20401@some.email\n\n" + "MAYBE_VALID_MAYBE_SUPPORTED\n\n" + "domain.end.with.nums@no.good.127\n" + "mason@日本.com\n" + "user@example.😀\n" + "☹️@hello.world\n\n" + "VALID_UNSUPPORTED\n\n" + "hns@neel\n" + "admin@mailserver1\n" + "\" \"@example.org\n" + "\"john..doe\"@example.org\n" + "\"very.(),:;<>[]\\\".VERY.\\\"very@\\\\ \\\"very\\\".unusual\"@strange.example.com\n" + "postmaster@[123.123.123.123]\n" + "postmaster@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334]\n\n" + "INVALID\n\n" + "hello..world@co.co\n" + "hello@world-.co\n" + "hello@.world.co\n" + "Abc.example.com\n" + "A@b@c@example.com\n" + "a\"b(c)d,e:f;g<h>i[j\\k]l@example.com\n" + "just\"not\"right@example.com\n" + "this is\"not\\allowed@example.com\n" + "this\\ still\\\"not\\\\allowed@example.com\n" + "1234567890123456789012345678901234567890123456789012345678901234+x@example.com\n" + "i_like_underscore@but_its_not_allowed_in_this_part.example.com\n" + "QA[icon]CHOCOLATE[icon]@test.com"; final Pattern pattern = Pattern.compile(regex, Pattern.UNICODE_CASE | 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