Regular Expressions 101

Save & Share

  • Save new Regex
    ctrl+s
  • Update 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
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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/

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 = "^( *)( *)( *)(['.-])((?!\\4)(?4)+?)((?!\\4|\\5)(?4)++)\\1\\3whale\n" + "(?=.(.))\\6.\\7\\4(?!\\4|\\6)([_\\/])\\3(?!(?11))\\8\\2(?=\\2)\\3\\1_((?=\\4+.).\\5(?!\\6)\\5)(?!.?')\\7\\4\n" + "(?=.\\7)\\6.([,`])\\3{2}(?=.((?!\\8)[_\\/])\\11)\\Q(_\\E.\\4{2}(?!\\.)\\5((?!\\10)(?10)(?!\\4+|\\5|\\6))\\1\\3{3}(\\\\)\n" + "(\\3{3})\\13\\2{2}\\1{1}\\3+(?<=\\S {10})\\4\\1\\3\\|\n" + "\\1(?=\\12)(?12)(?!`,)\\10\\4(\\11{2})\\4\\14\\10\\15\\9\\8\n" + "\\14{2}(?=\\6)['-]\\4(?<!-)\\11\\8\\11\\4\\6\\11\\15\\.-|(?!)"; final String string = " .-' whale\n" + "'--./ / _.---.\n" + "'-, (__..-` \\\n" + " \\ . |\n" + " `,.__. ,__.--/\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