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"
"

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"([\.\w\?]+)\s+([\dABCDEF]+) - ([\dABCDEF]+)\s+([\dABCDEF]+)"# let regex = try! NSRegularExpression(pattern: pattern) let testString = #""" .noinit 00001000 - 00001012 13 DATA (1 bytes space 00001013 - 00001013) .ramcode 00001014 - 000017CB 7B8 DATA .bss 000017CC - 00002A6A 129F DATA (1 bytes space 00002A6B - 00002A6B) .data 00002A6C - 00002B35 CA DATA WARNING: Non-dotted segment name DSPSEGMENT2.DRIVER120 DSPSEGMENT2.DRIVER120 00002B36 - 00002B3D 8 DATA .ISOBUFFERS 00002B3E - 00002CBD 180 DATA .uart 00002CBE - 00002DBD 100 DATA (562 bytes space 00002DBE - 00002FEF) .qspidata 00002FF0 - 00002FFF 10 DATA .icache 00003000 - 00003FFF 1000 DATA (20480 bytes space 00004000 - 00008FFF) .rsstack0 00009000 - 000092FF 300 DATA .rsmails0 00009300 - 000096FF 400 DATA .trace 00009700 - 000098FF 200 DATA """# let stringRange = NSRange(location: 0, length: testString.utf16.count) if let firstMatch = regex.firstMatch(in: testString, range: stringRange) { let result: [String] = (1 ..< firstMatch.numberOfRanges).map { (testString as NSString).substring(with: firstMatch.range(at: $0)) } print(result) } else { print("No matches were found.") }

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