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 = #"(?i)(?=(\d)\d)(?<![\d\-\x{2013}\x{2014}%])(?!000|666|9\d\d|\d{3}00|\d{5}0000|\1{9}|012345678|123456789|234567890|098765432|876543210|078051120|219099999)\d{9}(?![\d\-\x{2013}\x{2014}%])(?!\.(?:pdf|docx?|xlsx?|pptx?|zip|jpe?g|png|txt|log)\b)"# let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines) let testString = #################""" ################ ## Must match: ################ 009958881 123454891 is my ssn my ssn is 123454891 my ssn is 123454891 ok? my ssn is 123454891. my ssn is:123454891. # This one sneaks though, but we can live with that, maybe? myssnnumberis123454891ok? ################ ## Must not match: ################ # All-Zero group sequences 231840000 231007289 000877289 # Starting with 9 908780485 # Starting with 666 666780485 # Same number sequences: 222222222 555555555 # Ascending/Descending sequences: 123456789 87654321 # Known invalidated SSN: 219099999 078051120 # File names with common extensions: 123454891.pdf 123454891.xlsx Check the attachment: 123454891.xls, then get back to me. Check the attachment: 123454891.jpeg, then get back to me. # Extra digits: 1123454891 1234548911 # Unsupported boundaries: –123454891 —123454891 %123454891 123454891- 123454891— 123454891% 1-123454891 123454891-1 # Valid SSN with separators: 123-45-4891 098-18-6564 123-45-4848 702-02-0202 001-14-0004 009 95 8881 123-45-4891 is my ssn my ssn is 123-45-4891 my ssn is 123-45-4891 ok? my ssn is 123-45-4891. 123 45 4891 is my ssn my ssn is 123 45 4891 my ssn is 123 45 4891 ok? my ssn is 123 45 4891. my ssn is:123-45-4891. my ssn is:123 45 4891. ss#123-45-4891 ssn123-45-4891 # Emdash separator: 123–45–4891 # Endash separator: 123—45—4891 # Slash separator 123/45/4891 # Telephone 1-234-567-8901 1-234-567-8901 1-234-567-8901 1 (234) 567-8901 12347658901 # Credit card 5500 0000 0000 0004 3400 0000 0000 009 3000 0000 0000 04 5500-1244-2232-0004 3400-1244-0000-009 3000-1244-1234-04 # Random Numbers 1234567890112371298739872891738912738937289d712897381297381927d3128937893d7218947d1892742189duc89789v127c897412987893c12893c79 122-426-389 187-5-43212 187-0-43212 2423-45-6789 # Unsupported boundaries: ssn-123-45-4891 123-45-4891-ssn """################# 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