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

r"
"
gsm

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"([A-Z][a-z]{2} [A-Z][a-z]{2} \d{2} \d{2}:\d{2}:\d{2} CET \d{4})\n(/dev.*?) ==> (.*?)\n.*?\n(\d*) bytes .*? copied, (.*?) s, (.*?) (.*?s\n)(.*?)Exit status: (\d*)\n"# let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .dotMatchesLineSeparators]) let testString = #""" Thu Feb 11 15:01:37 CET 2021 /dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000 1+0 records in 1+0 records out 512 bytes (512 B) copied, 0.00383015 s, 134 kB/s Command being timed: "dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync" User time (seconds): 0.00 System time (seconds): 0.00 Percent of CPU this job got: 25% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 812 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 252 Voluntary context switches: 4 Involuntary context switches: 1 Swaps: 0 File system inputs: 0 File system outputs: 8 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 Thu Feb 11 16:02:17 CET 2021 /dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000 1+0 records in 1+0 records out 512 bytes (512 B) copied, 0.00275458 s, 186 kB/s Command being timed: "dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync" User time (seconds): 0.00 System time (seconds): 0.00 Percent of CPU this job got: 33% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 816 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 253 Voluntary context switches: 4 Involuntary context switches: 1 Swaps: 0 File system inputs: 0 File system outputs: 8 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 Thu Feb 11 17:02:26 CET 2021 /dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000 1+0 records in 1+0 records out 512 bytes (512 B) copied, 0.00323523 s, 158 kB/s Command being timed: "dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync" User time (seconds): 0.00 System time (seconds): 0.00 Percent of CPU this job got: 25% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 820 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 252 Voluntary context switches: 4 Involuntary context switches: 1 Swaps: 0 File system inputs: 0 File system outputs: 8 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 """# 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