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

re = /(?<=<!-- Template Nav Start -->[\n])([\n\s\S]*?)(?=[\s\n]*?<!-- Template Nav End -->)/m str = '<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta property="og:site_name" content="WD Proposal"> <meta property="og:title" content="Your new outdoor living space."> <meta property="og:image" content="https://www.WhitmerDecks.com/Proposal/eProposal/img/wdLogoName.png"> <meta property="og:description" content="Here you can view the proposal from Whitmer Decks, LLC"> </meta> <!-- General scripts & styles --> <link rel="stylesheet" href="css/styles.css"> <link rel="stylesheet" href="css/cwBootstrap.css"> <script src="js/cwBootstrap.js" defer></script> <!-- Google Fonts --> <link href="https://fonts.googleapis.com/css?family=Roboto:300,400,500,700&display=swap" rel="stylesheet"> <!-- Page title and end of general head --> <title>WD Proposal</title> <!-- Page specific scripts and styles --> <script src="js/about.js" defer></script> </head> <body> <!-- Template Nav Start --> <nav> <ul> <li><a href="index.html">Home</a></li> <li><a href="about.html">About</a></li> <li>Item X</li> <li>Item Y</li> </ul> </nav> <!-- Template Nav End --> <p> The about page </p> </body> </html>' # Print the match result str.scan(re) do |match| puts match.to_s end

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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html