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
Processing...

Test String

Code Generator

Generated Code

import re regex = re.compile(r""" (?: <\?php (?: [^"'\/<\?]+ | (?: "(?:[^\\"]|\\[\s\S])*" | # '(?:[^\\']|\\[\s\S])*' #| \/\*(?:[^\*]|\*[^\/])*\*\/ | (?:\#|\/\/).+(?:\n|$) | (?: <<<\s* (?: (?:'([a-zA-Z0-9_]+)'\s*?\n)(?:[^\n]*\n)*?\s*\1\s*?;?\s*?(?:\n|$) | (?:([a-zA-Z0-9_]+)\s*?\n)(?:[^\n]*\n)*?\s*\2\s*?;?\s*?(?:\n|$) ) ) ) | (?:[^?]|\?[^>]) )* (?:\?>|$) ) """, flags=re.VERBOSE | re.IGNORECASE) test_str = ("<!--\n" " The PHP masterpage\n" "-->\n" "<?php\n" "$matches = array();\n" "// separates \n" "$re = <<<PREG\n" " /^\n" " \n" " (?:\\\\s*(?:<!--.*?-->))*\n" " <\\\\?php\\\\s*include\\\\s*(\\\\()?\\\\s*([\\\\'\\\\\"])(?:(?!\\\\2).)*(?-i)Master\\\\.php(?i)\\\\2(?(-2)\\\\))\\\\s*;\\\\s*\\\\?>\\\\s*\n" " (?:\\\\s*(?:<!--.*?-->))*\n" " <master\\\\s*src=([\\\\'\\\\\\\"])(?<master_url>.+?)\\\\3\\\\/>(?<content>[\\s\\S]*)\n" " $\n" " /ix\n" "PREG;\n\n\n" "$re = <<<PREG2\n" " /^\n" " \n" " (?:\\\\s*(?:<!--.*?-->))*\n" " <\\\\?php\\\\s*include\\\\s*(\\\\()?\\\\s*([\\\\'\\\\\"])(?:(?!\\\\2).)*(?-i)Master\\\\.php(?i)\\\\2(?(-2)\\\\))\\\\s*;\\\\s*\\\\?>\\\\s*\n" " (?:\\\\s*(?:<!--.*?-->))*\n" " <master\\\\s*src=([\\\\'\\\\\\\"])(?<master_url>.+?)\\\\3\\\\/>(?<content>[\\s\\S]*)\n" " $\n" " /ix\n" "PREG2;\n\n" "$raw = file_get_contents(filter_input(INPUT_SERVER, 'SCRIPT_FILENAME'));\n" "preg_match($re, $raw, $matches);\n\n" "$master = file_get_contents($matches[\"master_url\"]);\n" "$child = $matches[\"content\"];\n\n" "$child_txt = eval2str($child);\n\n" "$master_txt = eval2str($master);\n\n" "$placeholder_xml = new DOMDocument();\n" "@$placeholder_xml->loadHTML($master_txt, LIBXML_NOWARNING);\n\n" "$child_xml = new DOMDocument();\n" "@$child_xml->loadHTML($child_txt, LIBXML_NOWARNING);\n\n" "$child_elems = $child_xml->getElementsByTagName(\"content\");\n\n\n" "foreach($child_elems as $c)\n" "{\n" " $name = $c->getAttribute(\"name\");\n" " $child_map[$name] = $placeholder_xml->importNode($c, true);\n" "}\n\n" "$placeholder_elems = $placeholder_xml->getElementsByTagName(\"placeholder\");\n" "while($placeholder_elems->length > 0)\n" "{\n" " $oldnode = $placeholder_elems->item(0);\n" " $name = $oldnode->getAttribute(\"name\");\n" " \n" " if(!isset($child_map[$name]))\n" " {\n" " $newnode = $placeholder_xml->createElement(\"content\");\n" " $attr = $placeholder_xml->createAttribute(\"name\");\n" " $attr->value = $name;\n" " $newnode->appendChild($attr);\n" " $child_map[$name] = $newnode;\n" " }\n" " $newnode = $child_map[$name];\n" " \n" " $parent = $oldnode->parentNode;\n" " \n" " $parent->replaceChild($newnode, $oldnode);\n" " $placeholder_elems = $placeholder_xml->getElementsByTagName(\"placeholder\"); // \n" "}\n\n" "die($placeholder_xml->saveHTML()); // to end execution of the remaining code in the calling file\n" "/*\n\n" "*/\n" "function eval2str($code)\n" "{\n" " ob_start();\n" " eval(\"?>$code\");\n" " return ob_get_clean();\n" "}\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