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

/
/
gm

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"VSID_W_MAX_TRAN_DT.+?=(?=\s) (?<VSID_W_MAX_TRAN_DT>[^\s]+)"# let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines) let testString = #""" VMID_COUNT =========== 20,588,655 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed Table.+.+?(?=\.)\W*(opcode_tedc_cs_gmr_id_delta)\W.+?(?=,+)\,\s+numRows\=+(?<LogTime>[^\,]+) Loading data to table gmr.opcode_tedc_cs_gmr_id_delta Table gmr.opcode_tedc_cs_gmr_id_delta stats: [numFiles=5, numRows=8986691, totalSize=937732401, rawDataSize=928745710] 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 997 100 997 0 0 114k 0 --:--:-- --:--:-- --:--:-- 162k 0 0 0 397 0 0 1650 0 --:--:-- --:--:-- --:--:-- 1650 VSID_W_MAX_TRAN_DT ========== 9,070,691 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 997 100 997 0 0 108k 0 --:--:-- --:--:-- --:--:-- 139k 0 0 0 403 0 0 944 0 --:--:-- --:--:-- --:--:-- 944 NON_PSP_VSID_COUNT =========== 39,869,169 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 997 100 997 0 0 112k 0 --:--:-- --:--:-- --:--:-- 162k 0 0 0 398 0 0 7223 0 --:--:-- --:--:-- --:--:-- 7223 PSP_VSID_COUNT =========== 45,083 sendmail: warning: inet_protocols: disabling IPv6 name/address support: Address family not supported by protocol postdrop: warning: inet_protocols: disabling IPv6 name/address support: Address family not supported by protocol [send_coll_stats.sh:] Sent e-mail with collection stats /jobs/prod/proclib/CMLS_HADOOP_proc_v02.ksh: line 75: print: command not found /jobs/prod/proclib/CMLS_trailer.ksh: line 9: print: command not found """# let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } print(result)

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