Regular Expressions 101

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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 = #"\b(127\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|0?10\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|172\.0?1[6-9]\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|172\.0?2[0-9]\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|172\.0?3[01]\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|192\.168\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|169\.254\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|::1|[fF][cCdD][0-9a-fA-F]{2}(?:[:][0-9a-fA-F]{0,4}){0,7}|[fF][eE][89aAbB][0-9a-fA-F](?:[:][0-9a-fA-F]{0,4}){0,7})(?:\/([789]|1?[0-9]{2}))?\b"# let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines) let testString = ##""" # loopback 127.0.0.0 127.0.0.0000 # only three digits supported here # A 10.0.0.1/10 10.255.22.33 # B 172.17.100.155/32 # C 192.168.1.1 192.168.1.255 # IPv6 fc00:833e:d648:f196:5c6c:1d9a:a14b:0d59 fc01:67e5::6a66:34a7 FC02:5fcf:e093:bb10:ce77:b5c9::/112 fc03:49bd:b7c1:5685:fa0a:87e9::2/128 fc04:::2 hmpf # Public IP addresses 0de9:b022:883f:2c3c:7dba:a184:7576:4531 04e4:e53b:0c2f:2990:27ad:0464:6dd3:b6b3 0319:3b4a:546e:d480:4814:f885:3396:bba2 5394:03f5:606f:273e:e343:d94a:610a:3f2e 63cd:ad1f:7ffb:62c7:cc17:6e20:9b59:2f7d # More "crap" 30.168.1.255.1 127.1 192.168.1.256 -1.2.3.4 1.1.1.1. 3...3 255.255.255.255 0.0.0.0 1.1.1.01 192.99.16.30 # decimal vs. octal mix 172.032.33.33 172.033.33.33 # octal - not supported here 0254.0021.0062.0041 # link-local addresses IPv4 169.254.1.0 169.254.254.255 # link-local addresses IPv6 fe90:1234::/64 feaf:ffff::/128 febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff """## 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