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

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?<!```html\\s*)(<link href=.*?)(?=^\\s*$)"; final String string = "\n" + "# PATTERNS\n\n" + "## Style Blocks (2 patterns)\n" + "- ***Matches:***\n" + " - All `<style> any code here </style> blocks that aren't preceded by ```css + any amount of optional whitespace\n\n" + ">> NOTES FOR THE FOLLOWING PATTERN: \n" + " • This requires the `regex` library, not Python's built-in-crap\n" + " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" + "### Pattern: Old version (would have replaced all punctuation with `punctuation` from the string library)\n" + " (?<!```css\\s*)(\\<style\\>[\\sa-z0-9\\-\\.\\[\\{\\]\\}:;#]+\\<\\/style\\>)\n\n" + ">> NOTES FOR THE FOLLOWING PATTERN: \n" + " • This requires the `regex` library, not Python's built-in-crap\n" + " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" + "### Pattern: Newest version (much better)\n" + " (?<!```css\\s*)(<style>.*?<\\/style>)\n\n" + "## This does the same thing but for `<!DOCTYPE html> any code here </html>`\n\n" + ">> NOTES FOR THE FOLLOWING PATTERN: \n" + " • This requires the `regex` library, not Python's built-in-crap\n" + " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" + "### Pattern:\n" + " (?<!```html\\s*)(<!DOCTYPE html>.*?<\\/html>)\n\n" + "## This matches all blocks of code containing `<link href=>` up to, but not including, an empty line\n\n" + ">> NOTES FOR THE FOLLOWING PATTERN: \n" + " • This requires the `regex` library, not Python's built-in-crap\n" + " • This requires the `Single Line` (regex101) or `regex.DOTALL` (Python regex) flag\n\n" + "### Pattern:\n" + " (?<!```html\\s*)(<link href=.*?)(?=^\\s*$)\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"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE | Pattern.DOTALL); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html