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

r"
"

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 = "(?i):/([^:]+)(?=/lib/neo4j-kernel-\\S+\\.jar)"; final String string = " java -cp /var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/concurrentlinkedhashmap-lru-1.4.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/lucene-core-3.6.2.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-backup-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cluster-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-com-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-consistency-check-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-csv-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cypher-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cypher-compiler-1.9-2.0.4.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cypher-compiler-2.0-2.0.4.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cypher-compiler-2.1-2.1.8.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-cypher-compiler-2.2-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-graph-algo-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-graph-matching-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-ha-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-import-tool-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-io-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-jmx-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-kernel-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-lucene-index-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-management-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-primitive-collections-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-query-logging-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-shell-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-udc-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/neo4j-unsafe-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/netty-3.6.3.Final.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/opencsv-2.3.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/org.apache.servicemix.bundles.jline-0.9.94_1.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/parboiled-core-1.1.7.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/parboiled-scala_2.10-1.1.7.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/scala-library-2.10.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/server-api-2.2.5.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/lib/slf4j-api-1.7.7.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/bcprov-jdk16-140.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-beanutils-1.8.3.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-compiler-2.6.1.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-configuration-1.10.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-digester-2.1.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-io-2.4.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-lang-2.6.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/commons-logging-1.1.1.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jackson-core-asl-1.9.13.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jackson-jaxrs-1.9.13.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jackson-mapper-asl-1.9.13.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/janino-2.6.1.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/javax.servlet-api-3.1.0.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jcl-over-slf4j-1.7.7.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jersey-core-1.19.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jersey-multipart-1.19.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jersey-server-1.19.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jersey-servlet-1.19.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jetty-http-9.2.4.v20141103.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/system/lib/jetty-io-9.2.4.v20141103.jar:/var/www/neo4j-ent/neo4j-enterprise-2.2.5/syste\n"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (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