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

/
/
gmx

Test String

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r""" A\s+change\s+to\s+ (?:(?:sub)?headings?|tariff\s+item) \s+\d[0-9.]* (?:\s+through\s+\d[0-9.]*)? \s+from(?:(?:,?\s+(?:sub)?headings?\s+\d[0-9.]*)+(?:\s+or\s+\d[0-9.]*)*\s+or)? \s+any\s+other\s+(?:heading|chapter)\. """ test_str = ("A change to headings 0101 through 0106 from any other chapter.\n" "A change to subheadings 0712.20 through 0712.39 from any other chapter.\n" "A change to heading 0903 from any other chapter.\n" "A change to subheading 1806.20 from any other heading.\n" "A change to subheading 1207.99 from any other chapter.\n" "A change to heading 4302 from any other heading.\n" "A change to subheading 4105.10 from heading 4102 or any other chapter.\n" "A change to subheading 4105.30 from heading 4102, subheading 4105.10 or any other chapter.\n" "A change to subheading 4106.21 from subheading 4103.10 or any other chapter.\n" "A change to subheading 4106.22 from subheadings 4103.10 or 4106.21 or any other chapter.\n" "A change to tariff item 7304.41.30 from subheading 7304.49 or any other chapter.") matches = re.finditer(regex, test_str, re.MULTILINE | re.VERBOSE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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