Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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

/
/
g

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"<img src="(?<SRC>[^"]+)" width="(?<WIDTH>[^"]*)" alt="(?<ALT>[^"]*)" title="(?<TITLE>[^"]*)" \/>"# let regex = try! NSRegularExpression(pattern: pattern) let testString = ##""" --- creation date: 2023-01-06 20:04 description: A test file modification date: 2023-01-14 10:17 obsidianUIMode: source tags: - programming --- This is the child file # Embed2 Your modes, all markdown ones: **1** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="The Asexual Flag" title="The Asexual Flag" /> **2** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="" title="" /> 3 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="The Asexual Flag" title="The Asexual Flag" /> 4 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="The Asexual Flag" title="The Asexual Flag" /> // Wikilink-embeds: **5** ![](001%20assets/AsexualPrideFlag.png) 6 ![](001%20assets/AsexualPrideFlag.svg) // Wikilink-embeds with names: **7** <img src="001%20assets/AsexualPrideFlag.png" width="" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> 8 <img src="001%20assets/AsexualPrideFlag.svg" width="" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> // Wikilink-embeds with sizing **9** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="" title="" /> 10 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="" title="" /> // Wikilink-embeds with sizing and names **11** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> 12 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> // Markdown-embeds: **13** ![](001%20assets/AsexualPrideFlag.png) 14 ![](001%20assets/AsexualPrideFlag.svg) // Markdown-embeds with names: **15** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> 16 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> // Markdown-embeds with sizing **17** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="" title="" /> 18 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="" title="" /> // Markdown-embeds with sizing and names **19** <img src="001%20assets/AsexualPrideFlag.png" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> 20 <img src="001%20assets/AsexualPrideFlag.svg" width="100" alt="Asexual Pride Flag" title="Asexual Pride Flag" /> All images with at **bolded numbers** are PNG's, all others SVG's. # EOF """## 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