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

/
/
gmi

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = ##"^(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?))(,(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?)))*\s(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?))(,(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?)))*\s(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?))(,(((\*|(\d\d?))(\/\d\d?)?)|(\d\d?\-\d\d?)))*\s(\?|(((\*|(\d\d?L?))(\/\d\d?)?)|(\d\d?L?\-\d\d?L?)|L|(\d\d?W))(,(((\*|(\d\d?L?))(\/\d\d?)?)|(\d\d?L?\-\d\d?L?)|L|(\d\d?W)))*)\s(((\*|(\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))(\/\d\d?)?)|((\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)\-(\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)))(,(((\*|(\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))(\/\d\d?)?)|((\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)\-(\d|10|11|12|JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC))))*\s(((\*|([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?)(\/\d\d?)?)|(([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?\-([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?)|([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?#([1-5]))(,(((\*|([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?)(\/\d\d?)?)|(([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?\-([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?)|([0-7]|MON|TUE|WED|THU|FRI|SAT|SUN)L?#([1-5])))*$"## let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .caseInsensitive]) let testString = ##""" * * * * * * * * * * * * * * * * * * 3 * * * * * 3 * * * * * 3 * * * * * 3 * * * * * 3 * * * * * 5/15 * * * * * 5/15 * * * * * 5/15 * * * * * 5/15 * * * * * 5/15 * * * * * 7,19 * * * * * 7,19 * * * * * 7,19 * * * * * 2-45 * * * * * 2-4 * * * * * 42-45 * * * * * 42-45 * * * * * 42-45 * * * * * 42-45 * * * * * 42-63 * * * * * 0 3 * * * * 0 3 * * * * 0 0/15 * * * * 0 0/15 * * * * 0 0/15 * * * * 0 0/15 * * * * 0 7,19 * * * * 0 7,19 * * * * 0 * 3 * * * 0 * 3 * * * 0 * 3 * * * 0 * 0/15 * * * 0 * 0/15 * * * 0 * 0/15 * * * 0 * 0/15 * * * 0 * 0/15 * * * 0 * 7,19 * * * 0 * 7,19 * * * 0 * 7,19 * * * 0 1 * * * * 0 0 * * * * 0 * * 3 * * 0 * * 3 * * 0 * * 3 * * 0 * * 3 * * 0 0 0 1/15 * * 0 0 0 1/15 * * 0 0 0 1/15 * * 0 0 0 1/15 * * 0 0 0 7,19 * * 0 0 0 7,19 * * 0 0 0 7,19 * * 0 0 0 7,19 * * 0 0 0 L * * 0 0 0 L * * 0 0 0 3L * * 0 0 0 3L * * 0 0 0 9W * * 0 0 0 9W * * 0 0 0 9W * * 0 0 0 9W * * 0 0 0 9X */2 * 0 0 0 9#2 * * 0 0 0 1 5 * 0 0 0 1 5/2 * 0 0 0 1 5/2 * 0 0 0 1 5/10 * 0 0 0 1 3,7,12 * 0 0 0 1 3,7,12 * 0 0 0 1 3,7,12 * 0 0 0 1 MAR,JUL,DEC * 0 0 0 1 MAR,JUL,DEC * 0 0 0 1 MAR,JUL,DEC * 0 0 0 1 ? * 0 0 0 * * 3 0 0 0 * * 3 0 0 0 * * 3 0 0 0 * * 3 0 0 0 * * 3/2 0 0 0 * * 3/2 0 0 0 * * 3/2 0 0 0 * * 3/2 0 0 0 * * 1,5,7 0 0 0 * * 1,5,7 0 0 0 * * 1,5,7 0 0 0 * * MON,FRI,SUN 0 0 0 * * MON,FRI,SUN 0 0 0 * * MON,FRI,SUN 0 0 0 * * 5L 0 0 0 * * 5L 0 0 0 * * 5L 0 0 0 * * FRIL 0 0 0 * * 5W 0 0 0 * * 5?3 0 0 0 * * 0 0 0 0 * * 0L 0 0 0 * * 0#2 0 0 0 * * 7 0 0 0 * * 7L 0 0 0 * * 7#2 0 0 0 * * 5#3 0 0 0 * * 5#3 0 0 0 * * 7#1 0 0 0 * * 7#1 0 0 0 * * 3#5 0 0 0 * * WED#5 * * 5-1 * * * """## 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