Regular Expressions 101

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  • 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
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Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"(?=(?:^(?:\d\d\d\d-(?:0[1-9]|10|11|12)-(?:0[1-9]|1[0-9]|2[0-8])|\d\d\d\d-(?:0[13-9]|10|11|12)-(?:29|30)|\d\d\d\d-(?:0[13578]|10|12)-31|(?:\d\d[2468][048]|\d\d0[48]|\d\d[13579][26])-02-29|(?:[02468][048]00|[13579][26]00)-02-29)T(?:(?:0[0-9]|1[0-9]|2[0-3]):(?:[0-5][0-9]):(?:[0-5][0-9]))(?:\.\d\d\d)?(?:Z|[\+\-](?:0[0-9]|1[012]):00|\+0[34569]:30|\+10:30|-0[39]:30|\+1[34]:00|\+0[58]:45|\+12:45)$)|^(?:1972|198[1235]|199[2347]|2012|2015)-06-30T23:59:60Z$|^(?:197[2-9]|1987|1989|199[058]|2005|2008|2016)-12-31T23:59:60Z$)(?!.*-00:00$)^(\d\d\d\d)-(\d\d)-(\d\d)T(\d\d):(\d\d):(\d\d)(?:\.(\d\d\d))?((Z)|([\+\-])(\d\d):(\d\d))$", flags=re.MULTILINE) test_str = ("Strong Matcher for ISO 8601 / RFC 3339 Date Times; rejects bad TZ offsets, illegal times (Museum of Bad Data)\n" "See below for expanded matcher\n\n" "```\n" "// accept: Exemplars\n" "2008-02-03T04:05:06.007Z\n" "2008-02-03T04:05:06Z\n" "0000-01-01T00:00:00.000Z\n" "0000-02-29T04:05:06.007Z\n" "9999-12-31T23:59:59.999Z\n" "9999-12-31T23:59:59Z\n" "2008-02-03T04:05:06.007+12:45\n" "2008-02-03T04:05:06+03:30\n" "0000-01-01T00:00:00.007-09:30\n" "0000-02-29T04:05:06.007+14:00\n" "9999-12-31T23:59:59.999+12:00\n" "9999-12-31T23:59:59-12:00\n" "// accept: Leap day, year is multiple of four\n" "0004-02-29T04:05:06.007Z\n" "0008-02-29T04:05:06.007Z\n" "0012-02-29T04:05:06.007Z\n" "0016-02-29T04:05:06.007Z\n" "0020-02-29T04:05:06.007Z\n" "0024-02-29T04:05:06.007Z\n" "0028-02-29T04:05:06.007Z\n" "0032-02-29T04:05:06.007Z\n" "0036-02-29T04:05:06.007Z\n" "0040-02-29T04:05:06.007Z\n" "0044-02-29T04:05:06.007Z\n" "0048-02-29T04:05:06.007Z\n" "0052-02-29T04:05:06.007Z\n" "0056-02-29T04:05:06.007Z\n" "0060-02-29T04:05:06.007Z\n" "0064-02-29T04:05:06.007Z\n" "0068-02-29T04:05:06.007Z\n" "0072-02-29T04:05:06.007Z\n" "0076-02-29T04:05:06.007Z\n" "0080-02-29T04:05:06.007Z\n" "0084-02-29T04:05:06.007Z\n" "0088-02-29T04:05:06.007Z\n" "0092-02-29T04:05:06.007Z\n" "0096-02-29T04:05:06.007Z\n" "1560-02-29T04:05:06.007Z\n" "2004-02-29T04:05:06.007Z\n" "2008-02-29T04:05:06.007Z\n" "2012-02-29T04:05:06.007Z\n" "2016-02-29T04:05:06.007Z\n" "2020-02-29T04:05:06.007Z\n" "2024-02-29T04:05:06.007Z\n" "2028-02-29T04:05:06.007Z\n" "2032-02-29T04:05:06.007Z\n" "2036-02-29T04:05:06.007Z\n" "2040-02-29T04:05:06.007Z\n" "2044-02-29T04:05:06.007Z\n" "9996-02-29T04:05:06.007Z\n" "// accept: Leap day, year is Multiple of 400\n" "0000-02-29T04:05:06.007Z\n" "0400-02-29T04:05:06.007Z\n" "0800-02-29T04:05:06.007Z\n" "1200-02-29T04:05:06.007Z\n" "1600-02-29T04:05:06.007Z\n" "2000-02-29T04:05:06.007Z\n" "2400-02-29T04:05:06.007Z\n" "2800-02-29T04:05:06.007Z\n" "3200-02-29T04:05:06.007Z\n" "3600-02-29T04:05:06.007Z\n" "4000-02-29T04:05:06.007Z\n" "4400-02-29T04:05:06.007Z\n" "4800-02-29T04:05:06.007Z\n" "5200-02-29T04:05:06.007Z\n" "5600-02-29T04:05:06.007Z\n" "6000-02-29T04:05:06.007Z\n" "6400-02-29T04:05:06.007Z\n" "6800-02-29T04:05:06.007Z\n" "7200-02-29T04:05:06.007Z\n" "7600-02-29T04:05:06.007Z\n" "8000-02-29T04:05:06.007Z\n" "8400-02-29T04:05:06.007Z\n" "8800-02-29T04:05:06.007Z\n" "9200-02-29T04:05:06.007Z\n" "9600-02-29T04:05:06.007Z\n" "// accept: Day in range for month\n" "2008-01-30T04:05:06.007Z\n" "2008-03-30T04:05:06.007Z\n" "2008-04-30T04:05:06.007Z\n" "2008-05-30T04:05:06.007Z\n" "2008-06-30T04:05:06.007Z\n" "2008-07-30T04:05:06.007Z\n" "2008-08-30T04:05:06.007Z\n" "2008-09-30T04:05:06.007Z\n" "2008-10-30T04:05:06.007Z\n" "2008-11-30T04:05:06.007Z\n" "2008-12-30T04:05:06.007Z\n" "2008-01-31T04:05:06.007Z\n" "2008-03-31T04:05:06.007Z\n" "2008-05-31T04:05:06.007Z\n" "2008-07-31T04:05:06.007Z\n" "2008-08-31T04:05:06.007Z\n" "2008-10-31T04:05:06.007Z\n" "2008-12-31T04:05:06.007Z\n" "// accept: had leap second\n" "1972-06-30T23:59:60Z\n" "1981-06-30T23:59:60Z\n" "1982-06-30T23:59:60Z\n" "1983-06-30T23:59:60Z\n" "1985-06-30T23:59:60Z\n" "1992-06-30T23:59:60Z\n" "1993-06-30T23:59:60Z\n" "1994-06-30T23:59:60Z\n" "1997-06-30T23:59:60Z\n" "2012-06-30T23:59:60Z\n" "2015-06-30T23:59:60Z\n" "1972-12-31T23:59:60Z\n" "1973-12-31T23:59:60Z\n" "1974-12-31T23:59:60Z\n" "1975-12-31T23:59:60Z\n" "1976-12-31T23:59:60Z\n" "1977-12-31T23:59:60Z\n" "1978-12-31T23:59:60Z\n" "1979-12-31T23:59:60Z\n" "1987-12-31T23:59:60Z\n" "1989-12-31T23:59:60Z\n" "1990-12-31T23:59:60Z\n" "1995-12-31T23:59:60Z\n" "1998-12-31T23:59:60Z\n" "2005-12-31T23:59:60Z\n" "2008-12-31T23:59:60Z\n" "2016-12-31T23:59:60Z\n" "// REJECT: Year out of range\n" "10000-02-29T04:05:06.007Z\n" "// REJECT: Month out of range\n" "2008-00-30T04:05:06.007Z\n" "2008-13-30T04:05:06.007Z\n" "2008-14-30T04:05:06.007Z\n" "2008-20-30T04:05:06.007Z\n" "// REJECT: Day out of range for month\n" "2008-02-30T04:05:06.007Z\n" "2008-04-31T04:05:06.007Z\n" "2008-06-31T04:05:06.007Z\n" "2008-09-31T04:05:06.007Z\n" "2008-11-31T04:05:06.007Z\n" "2008-02-31T04:05:06.007Z\n" "// REJECT: Day out of range\n" "2008-12-32T04:05:06.007Z\n" "2008-12-99T04:05:06.007Z\n" "2008-12-00T04:05:06.007Z\n" "// REJECT: Hour out of range\n" "2008-12-08T60:05:06.007Z\n" "2008-12-08T99:05:06.007Z\n" "// REJECT: Minute out of range\n" "2008-12-08T04:60:06.007Z\n" "2008-12-08T04:99:06.007Z\n" "// REJECT: Seconds out of range\n" "9999-12-31T59:59:61.999Z\n" "2008-02-03T04:05:61.999Z\n" "2008-02-03T04:05:61Z\n" "// REJECT: Negative dates not accepted\n" "-2000-02-29T04:05:06.007Z\n" "-0400-02-29T04:05:06.007Z\n" "-0100-02-29T04:05:06.007Z\n" "-0004-02-29T04:05:06.007Z\n" "// REJECT: stray characters\n" " 2008-12-31T04:05:06.007Z\n" "2008-12-31T04:05:06.007Z \n" "2008-12-31T04:05:06.007 Z\n" "// REJECT: Malformed\n" "2008-02-0304:05:06.007Z\n" "20080203T040506.007Z\n" "2008-02-03T04:05:06007Z\n" "2008-02-03T04:05:06.7Z\n" "2008-02-03T04:05:06.07Z\n" "2008-02-03T04:05:06.0007Z\n" "2008-02-03T04:05:06\n" "2008-02-03T04:05:06.Z\n" "// REJECT: no leap second\n" "1973-06-30T23:59:60Z\n" "1974-06-30T23:59:60Z\n" "1975-06-30T23:59:60Z\n" "1976-06-30T23:59:60Z\n" "1977-06-30T23:59:60Z\n" "1978-06-30T23:59:60Z\n" "1979-06-30T23:59:60Z\n" "1980-06-30T23:59:60Z\n" "1984-06-30T23:59:60Z\n" "1986-06-30T23:59:60Z\n" "1987-06-30T23:59:60Z\n" "1988-06-30T23:59:60Z\n" "1989-06-30T23:59:60Z\n" "1990-06-30T23:59:60Z\n" "1991-06-30T23:59:60Z\n" "1995-06-30T23:59:60Z\n" "1996-06-30T23:59:60Z\n" "1998-06-30T23:59:60Z\n" "1999-06-30T23:59:60Z\n" "2000-06-30T23:59:60Z\n" "2001-06-30T23:59:60Z\n" "2002-06-30T23:59:60Z\n" "2003-06-30T23:59:60Z\n" "2004-06-30T23:59:60Z\n" "2005-06-30T23:59:60Z\n" "2006-06-30T23:59:60Z\n" "2007-06-30T23:59:60Z\n" "2008-06-30T23:59:60Z\n" "2009-06-30T23:59:60Z\n" "2010-06-30T23:59:60Z\n" "2011-06-30T23:59:60Z\n" "2013-06-30T23:59:60Z\n" "2014-06-30T23:59:60Z\n" "2016-06-30T23:59:60Z\n" "2017-06-30T23:59:60Z\n" "2018-06-30T23:59:60Z\n" "2019-06-30T23:59:60Z\n" "2020-06-30T23:59:60Z\n" "2021-06-30T23:59:60Z\n" "2022-06-30T23:59:60Z\n" "2023-06-30T23:59:60Z\n" "1980-12-31T23:59:60Z\n" "1981-12-31T23:59:60Z\n" "1982-12-31T23:59:60Z\n" "1983-12-31T23:59:60Z\n" "1984-12-31T23:59:60Z\n" "1985-12-31T23:59:60Z\n" "1986-12-31T23:59:60Z\n" "1988-12-31T23:59:60Z\n" "1991-12-31T23:59:60Z\n" "1992-12-31T23:59:60Z\n" "1993-12-31T23:59:60Z\n" "1994-12-31T23:59:60Z\n" "1996-12-31T23:59:60Z\n" "1997-12-31T23:59:60Z\n" "1999-12-31T23:59:60Z\n" "2000-12-31T23:59:60Z\n" "2001-12-31T23:59:60Z\n" "2002-12-31T23:59:60Z\n" "2003-12-31T23:59:60Z\n" "2004-12-31T23:59:60Z\n" "2006-12-31T23:59:60Z\n" "2007-12-31T23:59:60Z\n" "2009-12-31T23:59:60Z\n" "2010-12-31T23:59:60Z\n" "2011-12-31T23:59:60Z\n" "2012-12-31T23:59:60Z\n" "2013-12-31T23:59:60Z\n" "2014-12-31T23:59:60Z\n" "2015-12-31T23:59:60Z\n" "2017-12-31T23:59:60Z\n" "2018-12-31T23:59:60Z\n" "2019-12-31T23:59:60Z\n" "2020-12-31T23:59:60Z\n" "2021-12-31T23:59:60Z\n" "2022-12-31T23:59:60Z\n" "2023-12-31T23:59:60Z\n" "// REJECT: assumes no future leap seconds\n" "2024-12-31T23:59:60Z\n" "2099-12-31T23:59:60Z\n" "9999-12-31T23:59:60Z\n" "// REJECT: leap seconds only in UTC format\n" "2005-12-31T23:59:60+00:00\n" "2008-12-31T23:59:60+00:00\n" "// REJECT: Not a leap day, year is not a multiple of four\n" "0101-02-29T04:05:06.007Z\n" "0102-02-29T04:05:06.007Z\n" "0103-02-29T04:05:06.007Z\n" "1537-02-29T04:05:06.007Z\n" "1538-02-29T04:05:06.007Z\n" "2001-02-29T04:05:06.007Z\n" "2002-02-29T04:05:06.007Z\n" "2003-02-29T04:05:06.007Z\n" "2021-02-29T04:05:06.007Z\n" "2022-02-29T04:05:06.007Z\n" "2023-02-29T04:05:06.007Z\n" "2025-02-29T04:05:06.007Z\n" "2026-02-29T04:05:06.007Z\n" "2027-02-29T04:05:06.007Z\n" "2029-02-29T04:05:06.007Z\n" "2030-02-29T04:05:06.007Z\n" "2031-02-29T04:05:06.007Z\n" "2033-02-29T04:05:06.007Z\n" "2034-02-29T04:05:06.007Z\n" "2035-02-29T04:05:06.007Z\n" "2037-02-29T04:05:06.007Z\n" "2038-02-29T04:05:06.007Z\n" "2039-02-29T04:05:06.007Z\n" "2041-02-29T04:05:06.007Z\n" "2042-02-29T04:05:06.007Z\n" "2043-02-29T04:05:06.007Z\n" "9997-02-29T04:05:06.007Z\n" "9998-02-29T04:05:06.007Z\n" "9999-02-29T04:05:06.007Z\n" "// REJECT: Not a leap day, year is a multiple of 100 but not 400\n" "0100-02-29T04:05:06.007Z\n" "0200-02-29T04:05:06.007Z\n" "0300-02-29T04:05:06.007Z\n" "0500-02-29T04:05:06.007Z\n" "0600-02-29T04:05:06.007Z\n" "0700-02-29T04:05:06.007Z\n" "0900-02-29T04:05:06.007Z\n" "1000-02-29T04:05:06.007Z\n" "1100-02-29T04:05:06.007Z\n" "1500-02-29T04:05:06.007Z\n" "2100-02-29T04:05:06.007Z\n" "2200-02-29T04:05:06.007Z\n" "2300-02-29T04:05:06.007Z\n" "2500-02-29T04:05:06.007Z\n" "2600-02-29T04:05:06.007Z\n" "2700-02-29T04:05:06.007Z\n" "2900-02-29T04:05:06.007Z\n" "3000-02-29T04:05:06.007Z\n" "3100-02-29T04:05:06.007Z\n" "3300-02-29T04:05:06.007Z\n" "3400-02-29T04:05:06.007Z\n" "3500-02-29T04:05:06.007Z\n" "3700-02-29T04:05:06.007Z\n" "```\n\n" "```\n" "(?=\n" " (?:^\n" " (?: # All non-leap-second YYYY-MM-DD parts:\n" " (?:\\d\\d\\d\\d-(?:0[1-9] |10|11|12)-(?:0[1-9]|1[0-9]|2[0-8])) # Days 01-28\n" " | (?:\\d\\d\\d\\d-(?:0[13-9] |10|11|12)-(29|30)) # Days 29+30\n" " | (?:\\d\\d\\d\\d-(?:0[13578]|10 |12)-31) # Day 31\n" " | (?:\\d\\d[2468][048]|\\d\\d0[48]|\\d\\d[13579][26])-02-29 # leap years not divisible by 100\n" " | (?:[02468][048]00|[13579][26]00)-02-29 # leap years divisible by 400\n" " )\n" " T\n" " (?:(?:0[0-9]|1[0-9]|2[0-3]):(?:[0-5][0-9]):(?:[0-5][0-9])) # time part\n" " (?:\\.\\d\\d\\d)? # ms part (optional)\n" " (?:Z|[\\+\\-](?:0[0-9]|1[012]):00|\\+0[34569]:30|\\+10:30|-0[39]:30|\\+1[34]:00|\\+0[58]:45|\\+12:45)\n" " $)\n" " |^(?:1972 |198[1235]|199[2347]|2012|2015 )-06-30T23:59:60Z$ # all june leapsecs\n" " |^(?:197[2-9]|1987|1989|199[058] |2005|2008|2016)-12-31T23:59:60Z$ # all december leapsecs\n" ")\n" "(?!.*-00:00$) # if given a -00:00 offset reject unconditionally, psychhhh\n" "# OK! Since only valid times are now possible, we can use a loose pattern match to parse.\n" "^(\\d\\d\\d\\d)-(\\d\\d)-(\\d\\d)T(\\d\\d):(\\d\\d):(\\d\\d)(?:\\.(\\d\\d\\d))?((Z)|([\\+\\-])(\\d\\d):(\\d\\d))$\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