Regular Expressions 101

Save & Manage Regex

  • Current Version: 1
  • Save & Share
  • Community Library

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
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
Processing...

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"^\[\S+\s+\S+\s+\S+\s+\S+\s+\S+\] \[(\w*:)?error\] (\[pid \d+(:tid \d+)?\] )?\[client (\S+)\] (\w+: )?ModSecurity:(( \[[^]]+\])*)? Access denied"# let regex = try! NSRegularExpression(pattern: pattern) let testString = #"[Sun Nov 08 14:58:57 2015] [error] [client 52.23.156.32] ModSecurity: [file "/etc/httpd/modsecurity.d/99_asl_zzzz_threat_intelligence.conf"] [line "73"] [id "355506"] [rev "1"] [msg "Atomicorp.com WAF Rules: Threat Intelligence Match for Known multi event attacker Source on Atomicorp Threat Intelligence RBL. See this URL for details http://www.atomicrbl.com/lookup"] [severity "ALERT"] Access denied with code 403 (phase 2). RBL lookup of 32.156.23.52.threat5.atomicrbl.com. succeeded at REMOTE_ADDR. [hostname "www.ourdomain.org"] [uri "/robots.txt"] [unique_id "Vj@3kaLy1rMAAAnKrs8AAAAY"]"# let stringRange = NSRange(location: 0, length: testString.utf16.count) if let firstMatch = regex.firstMatch(in: testString, range: stringRange) { let result: [String] = (1 ..< firstMatch.numberOfRanges).map { (testString as NSString).substring(with: firstMatch.range(at: $0)) } print(result) } else { print("No matches were found.") }

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 Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression