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

/
/
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 = "^(?:https?:\\/\\/)?(?:www\\.)?[\\d\\w\\.-]+(?:\\.|:)(?:[a-z\\.]{2,6}|\\d+)\\/?.*$"; final String string = "https://regex101.com/\n" + "https://www.variables.sh/complex-regular-expression-examples\n" + "https://search.brave.com/search?q=regex+challenges&source=desktop\n" + "https://web.whatsapp.com/\n" + "https://www.youtube.com/watch?v=fc_RvxTtIwc\n" + "https://text-auditor.netlify.app/\n" + "https://github.com/Dashrath-Sharma\n" + "http://github.com/Dashrath-Sharma\n" + "https://onecompiler.com/javascript/3zqzyu2g4\n" + "http://localhost:3000/\n" + "https://www.codingame.com/clashofcode/clash/report/3342454a92e4c660d772438bac8b2ef73de3c8f\n" + "https://react.dev/learn/thinking-in-react\n" + "https://dapp-world.com/course/introduction-to-solidity-Ynws/working-of-traditional-dapps-compared-to-dapps/reading\n\n" + "http://www.google.com\n" + "https://www.google.com\n" + "http://google.com\n" + "https://google.com\n" + "http://www.google.com/\n" + "https://www.google.com/\n" + "http://google.com/\n" + "https://google.com/\n" + "http://www.google.com/index.html\n" + "https://www.google.com/index.html\n" + "http://google.com/index.html\n" + "https://google.com/index.html\n"; 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