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

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "\\b(?:https?:\\/\\/)?[\\w-\\.$~!&'()*+,;=:%-]{3,50}:([\\w-\\.%$^#&'()*+,;=:%-]{3,50})@[a-zA-Z0-9.-]+(?:\\.[a-zA-Z]{2,})?\\b"; final String string = "### rgmz example\n" + "@----__-2as-2:password@----__-2as-2.com\n" + "### From test cases\n" + "var (\n" + " validPattern = \" https://kaNydBSAodo87dSAFtsd7.com:1234@qYY3SylY7fHP \"\n" + " validPattern2 = `<p><a href=\"http://username:password@127.0.0.1\">http://username:password@127.0.0.1</a></p>`\n" + " invalidPattern = \"https://kaNydBSAodo87dsm9asuiSAFtsd7.com.1234@qYY3SylY7fHP\"\n" + " keyword = \"uri\"\n" + ")\n" + "### examples from chatgpt\n" + "1. `https://user.name:pa$$word123@sub.example.com` \n" + "2. `http://u$er_name:my%p@$$word@api.dev.localhost` \n" + "3. `https://12345:67890@my-app.server123.co.uk` \n" + "4. `http://user~!name:pass.word@some-long-subdomain.example.org` \n" + "5. `https://_:__@localhost` \n" + "6. `https://admin:admin123@192.168.1.1` \n" + "7. `http://test-user:complex!password#123@server.example.io` \n" + "8. `https://valid_user:!valid-password@simple-host.co` \n" + "9. `http://username_with.dots:password_with-dashes@domain.with.subdomain.net` \n" + "10. `https://username:password@127.0.0.1:8080` \n" + "11. `http://user:pass@----__-2as-2` \n" + "12. `https://user@localhost` \n" + "13. `http://user:pass@:invalidhost` \n" + "14. `https://:passwordonly@hostname.com` \n" + "15. `ftp://username:password@hostname.com` \n" + "16. `https://user:password@hostname_with_underscores.com` \n" + "17. `http://user@:missingpassword.com` \n" + "18. `https://missingcolonpassword@hostname.com` \n" + "19. `http://user:password@-invalid-hostname.com` \n" + "20. `https://user:password@host..com` "; 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