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

/
/
gm

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 = "((asia|europe|us|australia)|((north|south)(america|africa)))-((east|west|central|north|south)|((north|south)(east)))([0-9]{1,2})"; final String string = "(east|west|central|north)?(north|south)?(east)[0-9]{1,2}\n" + "(east|west|central|north)(north|south)(east)[0-9]{1,2}\n\n" + "(north|south)(america)\n\n" + "FireStore Regions\n" + "us-west1 oregon\n" + "us-west2 Los Angeles\n" + "us-west3 Tuz Gölü şehri\n" + "us-west4 Las Vegas\n" + "northamerica-northeast1 Montreal\n" + "northafrica-west3\n" + "southafrica-east1\n" + "us-east1 Güney Carolina\n" + "us-east4 Kuzey Virginia\n" + "southamerica-east1 Sao Paulo\n" + "europe-west2 Londra\n" + "europe-west4\n" + "europe-west3 Frankfurt\n" + "europe-central2 Varşova\n" + "europe-west6 Zürih\n" + "asia-south1 Bombay\n" + "asia-southeast1 Singapur\n" + "asia-southeast2 Cakarta\n" + "asia-east2 Hong Kong\n" + "asia-east1 Tayvan\n" + "asia-northeast1 Tokyo\n" + "asia-northeast2 Osaka\n" + "asia-northeast3 Seul\n" + "australia-southeast1 Sidney\n" + "australia-southeast2\n\n" + "australia-southeast\n\n" + "Function Regions\n\n" + "asia-east1 (Tayvan)\n" + "asia-east2 (Hong Kong)\n" + "asia-northeast1 (Tokyo)\n" + "asia-northeast2 (Osaka)\n" + "europe-west1 (Belçika) \n" + "europe-west2 (Londra)\n" + "us-central1 (Iowa)\n" + "us-east1 (Güney Karolina)\n" + "us-east4 (Kuzey Virginia)\n" + "us-west1 (Oregon)\n" + "asia-northeast3 (Seul)\n" + "asia-southeast1 (Singapur)\n" + "asia-southeast2 (Cakarta)\n" + "asia-south1 (Mumbai)\n" + "australia-southeast1 (Sidney)\n" + "europe-central2 (Varşova)\n" + "europe-west3 (Frankfurt)\n" + "europe-west6 (Zürih) \n" + "northamerica-northeast1 (Montreal) \n" + "southamerica-east1 (Sao Paulo) \n" + "us-west2 (Los Angeles)\n" + "us-west3 (Salt Lake City)\n" + "us-west4 (Las Vegas)\n\n\n" + "asia-east1 (Tayvan) us-west2 (Los Angeles) europe-west1 (Belçika)\n" + "us-west3 (Salt Lake City) asia-northeast1 (Tokyo) southamerica-east1 (Sao Paulo)\n" + "us-west4 (Las Vegas) asia-east2 (Hong Kong) northamerica-northeast1 (Montreal)\n" + "europe-west2 (Londra) asia-south1 (Mumbai) europe-west3 (Frankfurt)\n" + "us-central1 (Iowa) europe-central2 (Varşova) europe-west6 (Zürih)\n" + "us-east1 (Güney Karolina)\n" + "asia-northeast3 (Seul)\n" + "us-east4 (Kuzey Virginia)\n" + "australia-southeast1 (Sidney)\n" + "us-west1 (Oregon)\n" + "asia-southeast2 (Cakarta)\n" + "asia-southeast1 (Singapur)"; 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