Regular Expressions 101

Save & Share

  • Regex Version: ver. 9
  • 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

/
/
g

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 = "([^\\s=]+)=('?)(\"?)([^>\"']*)\\2\\3"; final String string = " style=\"width: 462px;\" src='data:image/png;base64,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' data-filename=\"Screenshot from 2016-02-09 21:54:47.png\"\n\n\n" + "<tr><td><A HREF=\"brackets.html\" TARGET=\"_top\">Capturing group</A></td>\n" + " <td><TT>(regex)</TT></td>\n" + " <td>Parentheses group the regex between them. They capture the text matched by the regex inside them into a numbered group that can be reused with a numbered backreference. They allow you to apply regex operators to the entire grouped regex.</td>\n" + " <td><TT CLASS=code><SPAN CLASS=\"regexnest1\">(</SPAN><SPAN CLASS=\"regexplain\">abc</SPAN><SPAN CLASS=\"regexnest1\">)</SPAN><SPAN CLASS=\"regexspecial\">{3}</SPAN></TT> matches <TT CLASS=match>abcabcabc</TT>. First group matches <TT CLASS=match>abc</TT>.</td>\n" + "<td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>ECMA<br>extended<br>egrep<br>awk</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td><td class=yes>YES</td></tr>\n\n" + "<tr><td><A HREF=\"brackets.html\" TARGET=\"_top\">Capturing group</A></td>\n" + " <td><TT>\\(regex\\)</TT></td>\n" + " <td>Escaped parentheses group the regex between them. They capture the text matched by the regex inside them into a numbered group that can be reused with a numbered backreference. They allow you to apply regex operators to the entire grouped regex.</td>\n" + " <td><TT CLASS=code><SPAN CLASS=\"regexnest1\">\\(</SPAN><SPAN CLASS=\"regexplain\">abc</SPAN><SPAN CLASS=\"regexnest1\">\\)</SPAN><SPAN CLASS=\"regexplain\">{3}</SPAN></TT> matches <TT CLASS=match>abcabcabc</TT>. First group matches <TT CLASS=match>abc</TT>.</td>\n" + "<td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td>no</td><td class=yes>basic<br>grep</td><td>no</td><td class=yes>YES</td><td>no</td><td class=yes>YES</td><td>no</td><td>no</td><td>no</td><td>no</td></tr>\n\n" + "<tr><td><A HREF=\"brackets.html\" TARGET=\"_top\">Non-capturing group</A></td>\n"; final Pattern pattern = Pattern.compile(regex); 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