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

Substitution
Processing...

Code Generator

Language

Generated Code

import re regex = re.compile(r""" (?(DEFINE) (?<tagName> [a-z][a-z\d]*+ (?=[>\s/]) ) (?<tagAttr> (?> [^>"']++ | " [^"]*+ " | ' [^']*+ ' )*+ ) ) < (li|/ul) /?+ (?=[>\s/]) ((?&tagAttr)) > ((?: [^<]++ | < /?+ (?!(?:li|ul)(?=[>\s/])) (?&tagName) (?&tagAttr) > #any tag except <li> and <ul> | < (?! /?+ (?&tagName) ) #not tag )*) (?= < (?:li|/ul) (?=[>\s/]) (?&tagAttr) ) #check for nested <li> and <ul> """, flags=re.DOTALL | re.IGNORECASE | re.VERBOSE | re.UNICODE) test_str = ("<ul>\n" " <li fhgfhfg ghgfhfghhfgh= ghghg=\"...\" a = 'ghghg'>dfdsfsd\n" " <ul>\n" " <li>111</li>\n" " <li/>2222\n" " <li>mmmmm</li>\n" " </ul>\n" " <li>dfdsfdsfsdf <b class=\"...\"><br/>fgdfgd<i></b><!-- dfdf--><li>\n" " <li>\n" " <li>dsfsdfsdfdsf\n" "</ul>\n\n") subst = "<$3$4>$5</LI>\\r" result = regex.sub(subst, test_str) if result: print(result)

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