regex101: Dates

Non-Capturing Group(?:(?P<Day1>\d{1,2})(?:\W*(?P<Month1>[A-Z][a-z]*\b))|(?:(?P<Month2>[A-Z][a-z]*\b)\W*)(?:(?P<Day2>\d{1,2})(?:\b|th|st|nd))?|(?P<Month3>\d{1,2})\W+(?P<Day3>\d{1,2})|(?P<Month4>\d{1,2}))?

?repeats the group contents below at most once:

1st Alternative(?P<Day1>\d{1,2})(?:\W*(?P<Month1>[A-Z][a-z]*\b))

Group Day1(?P<Day1>\d{1,2})

\d{1,2}a Unicode decimal digit, repeated between 1 and 2 times

Non-Capturing Group(?:\W*(?P<Month1>[A-Z][a-z]*\b))

\W*any character that is not a Unicode word character, repeated any number of times

Group Month1(?P<Month1>[A-Z][a-z]*\b)

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

\ba Unicode word boundary

2nd Alternative(?:(?P<Month2>[A-Z][a-z]*\b)\W*)(?:(?P<Day2>\d{1,2})(?:\b|th|st|nd))?

Non-Capturing Group(?:(?P<Month2>[A-Z][a-z]*\b)\W*)

Group Month2(?P<Month2>[A-Z][a-z]*\b)

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[a-z]*

*matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

\ba Unicode word boundary

\W*any character that is not a Unicode word character, repeated any number of times

Non-Capturing Group(?:(?P<Day2>\d{1,2})(?:\b|th|st|nd))?

?repeats the group contents below at most once:

Group Day2(?P<Day2>\d{1,2})

\d{1,2}a Unicode decimal digit, repeated between 1 and 2 times

Non-Capturing Group(?:\b|th|st|nd)

1st Alternative\b

\ba Unicode word boundary

2nd Alternativeth

ththe literal text th (case sensitive)

3rd Alternativest

stthe literal text st (case sensitive)

4th Alternativend

ndthe literal text nd (case sensitive)

3rd Alternative(?P<Month3>\d{1,2})\W+(?P<Day3>\d{1,2})

Group Month3(?P<Month3>\d{1,2})

\d{1,2}a Unicode decimal digit, repeated between 1 and 2 times

\W+any character that is not a Unicode word character, repeated at least once

Group Day3(?P<Day3>\d{1,2})

\d{1,2}a Unicode decimal digit, repeated between 1 and 2 times

4th Alternative(?P<Month4>\d{1,2})

Group Month4(?P<Month4>\d{1,2})

\d{1,2}a Unicode decimal digit, repeated between 1 and 2 times

\W+?any character that is not a Unicode word character, repeated at least once

Group Year(?P<Year>\d{2,4}(?=$|;))

\d{2,4}a Unicode decimal digit, repeated between 2 and 4 times

Positive Lookahead(?=$|;)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

(?:(?P<Day1>\d{1,2})(?:\W*(?P<Month1>[A-Z][a-z]*\b))|(?:(?P<Month2>[A-Z][a-z]*\b)\W*)(?:(?P<Day2>\d{1,2})(?:\b|th|st|nd))?|(?P<Month3>\d{1,2})\W+(?P<Day3>\d{1,2})|(?P<Month4>\d{1,2}))?\W+?(?P<Year>\d{2,4}(?=$|;))

New

04/20/2009
04/20/09
4/20/09
4/3/09
Mar-20-2009
Mar 20, 2009
March 20, 2009
Mar. 20, 2009
Mar 20 2009;
20 Mar 2009
20 March 2009
20 Mar. 2009
20 March, 2009
Mar 20th, 2009
Mar 21st, 2009
Mar 22nd, 2009
Feb 2009
Sep 2009
Oct 2010
6/2008
12/2009
2009
2010

Regular Expressions 101

Regular Expression

Substitution