regex.txt

Meta Characters
[] A set of characters
\ Signals a special sequence (can also be used to escape special characters)
. Any character (except newline character)
^ Starts with
$ Ends with
* Zero or more occurrences
+ One or more occurrences
{} Exactly the specified number of occurrences
| Either or
() Capture and group

Special Sequences
\A Returns a match if the specified characters are at the beginning of the string
\b Returns a match where the specified characters are at the beginning or at the end of a word r"ain\b"
\B Returns a match where the specified characters are present, but NOT at the beginning (or at the end) of a word
\d Returns a match where the string contains digits (numbers from 0-9)
\D Returns a match where the string DOES NOT contain digits
\s Returns a match where the string contains a white space character
\S Returns a match where the string DOES NOT contain a white space character
\w Returns a match where the string contains any word characters (characters from a to Z, digits from 0-9, and the underscore _ character)
\W Returns a match where the string DOES NOT contain any word characters
\Z Returns a match if the specified characters are at the end of the string


[arn]	Returns a match where one of the specified characters (a, r, or n) are present
[a-n]	Returns a match for any lower case character, alphabetically between a and n
[^arn]	Returns a match for any character EXCEPT a, r, and n
[0123]	Returns a match where any of the specified digits (0, 1, 2, or 3) are present
[0-9]	Returns a match for any digit between 0 and 9
[0-5][0-9]	Returns a match for any two-digit numbers from 00 and 59
[a-zA-Z]	Returns a match for any character alphabetically between a and z, lower case OR upper case
[+]	In sets, +, *, ., |, (), $,{} has no special meaning, so [+] means: return a match for any + character in the string