Regular Expressions 101

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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

/
/
gmis

Test String

Code Generator

Language

Generated Code

re = /(?<!```html\s*)(<link href=.*?)(?=^\s*$)/mi str = ' # PATTERNS ## Style Blocks (2 patterns) - ***Matches:*** - All `<style> any code here </style> blocks that aren\'t preceded by ```css + any amount of optional whitespace >> NOTES FOR THE FOLLOWING PATTERN: • This requires the `regex` library, not Python\'s built-in-crap • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag ### Pattern: Old version (would have replaced all punctuation with `punctuation` from the string library) (?<!```css\\s*)(\\<style\\>[\\sa-z0-9\\-\\.\\[\\{\\]\\}:;#]+\\<\\/style\\>) >> NOTES FOR THE FOLLOWING PATTERN: • This requires the `regex` library, not Python\'s built-in-crap • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag ### Pattern: Newest version (much better) (?<!```css\\s*)(<style>.*?<\\/style>) ## This does the same thing but for `<!DOCTYPE html> any code here </html>` >> NOTES FOR THE FOLLOWING PATTERN: • This requires the `regex` library, not Python\'s built-in-crap • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag ### Pattern: (?<!```html\\s*)(<!DOCTYPE html>.*?<\\/html>) ## This matches all blocks of code containing `<link href=>` up to, but not including, an empty line >> NOTES FOR THE FOLLOWING PATTERN: • This requires the `regex` library, not Python\'s built-in-crap • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag ### Pattern: (?<!```html\\s*)(<link href=.*?)(?=^\\s*$) <br> (><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><) <br> # TEST TEXT <br> <style> .list-group-mine .list-group-item { background-color: black; color: white; border-top: 1px solid #0091b5; border-left-color: #fff; border-right-color: #fff; } .list-group-mine .list-group-item:hover { background-color: red; } </style> ```css <style> .list-group-mine .list-group-item { background-color: black; color: white; border-top: 1px solid #0091b5; border-left-color: #fff; border-right-color: #fff; } .list-group-mine .list-group-item:hover { background-color: red; } </style> ``` <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous"> <div class="list-group list-group-mine"> <a class="list-group-item" href="https://bit.ly/3SICqay"><strong>Link to the SO Post</strong></a> <a class="list-group-item" href="/path"><strong>Item 2</strong></a> <a class="list-group-item" href="/path"><strong>Item 3</strong></a> </div> <br> ##### Before Bootstrap <!DOCTYPE html> <html lang="en"> <head> <title>TABLE</title> </head> <body> <table> <thead> <tr> <th>Name</th> <th>Number</th> </tr> </thead> <tbody> <tr> <td>Malachi</td> <td>1-555-343-9867</td> </tr> <tr> <td>Steve</td> <td>1-555-734-8857</td> </tr> </tbody> </table> </body> </html> </br> <code style="color: #f51686; font-weight: bold; font-size: 16pt;"> The HTML </code> ```html <!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" /> <title>CSS Images</title> <link rel="stylesheet" href="css/style.css" /> </head> <body> <div class="container"> <section class="hero"> <figure class="profile-pic-figure"> <img src="img/profile-800x800.png" alt="profile" width="800" height="800" title="Profile Pic" /> <figcaption class="offscreen">Pookie Scrumptious</figcaption> </figure> <h1 class="h1"> <span class="nowrap"> Hello 👋 </span> <span class="nowrap"> I\'m Pookie </span> </h1> </section> </div> </body> </html> ``` <br> <code style="color: #f51686; font-weight: bold; font-size: 16pt;"> The CSS</code> ' # 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