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
  • 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
No Match

/
/
g

Test String

Code Generator

Language

Generated Code

const regex = /^([^\s]+)\s([^\s]+)\s([^\s]+)\s([^\s]+)\s+(?<server>[^\s]+)\s+\*(?<task>[^\s]+\:)\s+([^\s]+)\s+([^\s]+)\s+([^\s]+)\s+\%(?<status>[^\s]+)\s+(?<task1>[^\s]+)\s+(?<action>[^\s]+\')\s+\w+\s+\w+\:\s+(?<src_mac>[^\s]+)\s+\w+\s+\w+\:\s+(?<dest_mac>[^\s]+)\s+\w+\s\'\w+\'\s+(?<tast2>)\w+\s+\'(?<action2>[^\s]+)\s+\w+\s+\'\w+\'\s+\w+\s+\w+\s+\'(?<timesec>[^\s]+)\s+\w+/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('^([^\\s]+)\\s([^\\s]+)\\s([^\\s]+)\\s([^\\s]+)\\s+(?<server>[^\\s]+)\\s+\\*(?<task>[^\\s]+\\:)\\s+([^\\s]+)\\s+([^\\s]+)\\s+([^\\s]+)\\s+\\%(?<status>[^\\s]+)\\s+(?<task1>[^\\s]+)\\s+(?<action>[^\\s]+\\\')\\s+\\w+\\s+\\w+\\:\\s+(?<src_mac>[^\\s]+)\\s+\\w+\\s+\\w+\\:\\s+(?<dest_mac>[^\\s]+)\\s+\\w+\\s\\\'\\w+\\\'\\s+(?<tast2>)\\w+\\s+\\\'(?<action2>[^\\s]+)\\s+\\w+\\s+\\\'\\w+\\\'\\s+\\w+\\s+\\w+\\s+\\\'(?<timesec>[^\\s]+)\\s+\\w+', 'g') const str = `Feb 27 16:41:39 10.128.5.5 tc-cl-wlc01: *apfReceiveTask: Feb 27 16:41:38.944: %APF-3-NO_FRAMED_IP_ADDRESS: [PA]apf_radius.c:2456 'AcctStop' clt MAC: 14:32:d1:c9:43:58 AP MAC: c0:25:5c:60:ab:f0 Role 'Local' PemState 'START' SSID 'CPS' Connected for '126' secs`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions