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]
  • Character class intersection
    [\w&&[^\d]]
  • 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
Processing...

Test String

Code Generator

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Generated Code

import re regex = re.compile(r"(?<!```html\s*)(<link href=.*?)(?=^\s*$)", flags=re.MULTILINE | re.IGNORECASE | re.DOTALL) test_str = ("\n" "# PATTERNS\n\n" "## Style Blocks (2 patterns)\n" "- ***Matches:***\n" " - All `<style> any code here </style> blocks that aren't preceded by ```css + any amount of optional whitespace\n\n" ">> NOTES FOR THE FOLLOWING PATTERN: \n" " • This requires the `regex` library, not Python's built-in-crap\n" " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" "### Pattern: Old version (would have replaced all punctuation with `punctuation` from the string library)\n" " (?<!```css\\s*)(\\<style\\>[\\sa-z0-9\\-\\.\\[\\{\\]\\}:;#]+\\<\\/style\\>)\n\n" ">> NOTES FOR THE FOLLOWING PATTERN: \n" " • This requires the `regex` library, not Python's built-in-crap\n" " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" "### Pattern: Newest version (much better)\n" " (?<!```css\\s*)(<style>.*?<\\/style>)\n\n" "## This does the same thing but for `<!DOCTYPE html> any code here </html>`\n\n" ">> NOTES FOR THE FOLLOWING PATTERN: \n" " • This requires the `regex` library, not Python's built-in-crap\n" " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" "### Pattern:\n" " (?<!```html\\s*)(<!DOCTYPE html>.*?<\\/html>)\n\n" "## This matches all blocks of code containing `<link href=>` up to, but not including, an empty line\n\n" ">> NOTES FOR THE FOLLOWING PATTERN: \n" " • This requires the `regex` library, not Python's built-in-crap\n" " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" "### Pattern:\n" " (?<!```html\\s*)(<link href=.*?)(?=^\\s*$)\n\n" "<br>\n\n" "(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)(><)\n\n" "<br>\n\n" "# TEST TEXT\n\n" "<br>\n\n" "<style>\n" " .list-group-mine .list-group-item {\n" " background-color: black;\n" " color: white;\n" " border-top: 1px solid #0091b5;\n" " border-left-color: #fff;\n" " border-right-color: #fff;\n" " }\n" " .list-group-mine .list-group-item:hover {\n" " background-color: red;\n" " }\n" "</style>\n\n\n" "```css\n" "<style>\n" " .list-group-mine .list-group-item {\n" " background-color: black;\n" " color: white;\n" " border-top: 1px solid #0091b5;\n" " border-left-color: #fff;\n" " border-right-color: #fff;\n" " }\n" " .list-group-mine .list-group-item:hover {\n" " background-color: red;\n" " }\n" "</style>\n" "```\n\n" "<link href=\"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css\" rel=\"stylesheet\" integrity=\"sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u\" crossorigin=\"anonymous\">\n" "<div class=\"list-group list-group-mine\">\n" " <a class=\"list-group-item\" href=\"https://bit.ly/3SICqay\"><strong>Link to the SO Post</strong></a>\n" " <a class=\"list-group-item\" href=\"/path\"><strong>Item 2</strong></a>\n" " <a class=\"list-group-item\" href=\"/path\"><strong>Item 3</strong></a>\n" "</div>\n\n" "<br>\n\n" "##### Before Bootstrap\n" "<!DOCTYPE html>\n\n" "<html lang=\"en\">\n" " <head>\n" " <title>TABLE</title>\n" " </head>\n" " <body>\n" " <table>\n" " <thead>\n" " <tr>\n" " <th>Name</th>\n" " <th>Number</th>\n" " </tr>\n" " </thead>\n" " <tbody>\n" " <tr>\n" " <td>Malachi</td>\n" " <td>1-555-343-9867</td>\n" " </tr>\n" " <tr>\n" " <td>Steve</td>\n" " <td>1-555-734-8857</td>\n" " </tr>\n" " </tbody>\n" " </table>\n" " </body>\n" "</html>\n\n\n" "</br>\n\n" "<code style=\"color: #f51686; font-weight: bold; font-size: 16pt;\"> The HTML </code>\n\n" "```html\n" " <!DOCTYPE html>\n" " <html lang=\"en\">\n" " <head>\n" " <meta charset=\"UTF-8\" />\n" " <meta http-equiv=\"X-UA-Compatible\" content=\"IE=edge\" />\n" " <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" />\n" " <title>CSS Images</title>\n" " <link rel=\"stylesheet\" href=\"css/style.css\" />\n" " </head>\n\n" " <body>\n" " <div class=\"container\">\n" " <section class=\"hero\">\n" " <figure class=\"profile-pic-figure\">\n" " <img\n" " src=\"img/profile-800x800.png\"\n" " alt=\"profile\"\n" " width=\"800\"\n" " height=\"800\"\n" " title=\"Profile Pic\"\n" " />\n" " <figcaption class=\"offscreen\">Pookie Scrumptious</figcaption>\n" " </figure>\n" " <h1 class=\"h1\">\n" " <span class=\"nowrap\">\n" " Hello 👋\n" " </span>\n" " <span class=\"nowrap\">\n" " I'm Pookie\n" " </span>\n" " </h1>\n" " </section>\n" " </div>\n" " </body>\n" " </html>\n" "```\n\n" "<br>\n\n" "<code style=\"color: #f51686; font-weight: bold; font-size: 16pt;\"> The CSS</code>\n") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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 Python, please visit: https://docs.python.org/3/library/re.html