Regex Cheat Sheet

regex.txt

# http://ryanstutorials.net/regular-expressions-tutorial/
dot (.)   Match any character.
[ ]       Match a range of characters contained within the square brackets.
[^ ]      Match a character which is not one of those contained within the square brackets.
*         Match zero or more of the preceeding item.
+         Match one or more of the preceeding item.
?         Match zero or one of the preceeding item.
{n}       Match exactly n of the preceeding item.
{n,m}     Match between n and m of the preceeding item.
{n,}      Match n or more of the preceeding item.
\         Escape, or remove the special meaning of the next character.
String    A sequence of characters.
\s        Match any character which is considered whitespace (space, tab etc).
\S        Match any character which is not whitespace.
\d        Match any character which is a digit ( 0 - 9 ).
\D        Match any character which is not a digit.
\w        Match any character which is a word character ( A-Z, a-z, 0-9 and _ ).
\W        Match any character which is not a word character.
\t        Match a tab.
\r        Match a carriage return.
\n        Match a line feed (or newline).
^ (caret) An anchor which matches the beginning of the line.
$ (dollar)An anchor which matches the end of the line.
\b        Matches the beginning or end of a word.
\<        Matches the beginning of a word.
\>        Matches the end of a word.
( )       Group part of the regular expression.
\1 \2 etc Refer to something matched by a previous grouping.
|         Match what is on either the left or right of the pipe symbol.
(?=x)     Positive lookahead.
(?!x)     Negative lookahead.
(?<=x)    Positive lookbehind.
(?<!x)    Negative lookbehind.

#https://docs.python.org/3.7/howto/regex.html
{0,} is the same as *, {1,} is equivalent to +, and {0,1} is the same as ?. 

# https://www.analyticsvidhya.com/blog/2015/06/regular-expression-python/
Operators 	Description
.           Matches with any single character except newline ‘\n’.
?           match 0 or 1 occurrence of the pattern to its left
+           1 or more occurrences of the pattern to its left
*           0 or more occurrences of the pattern to its left
\w          Matches with a alphanumeric character whereas \W (upper case W) matches non alphanumeric character.
\d          Matches with digits [0-9] and /D (upper case D) matches with non-digits.
\s          Matches with a single white space character (space, newline, return, tab, form) and \S (upper case S)
              matches any non-white space character.
\b          boundary between word and non-word and /B is opposite of /b
[..]        Matches any single character in a square bracket and [^..] matches any single character not in square bracket
\           It is used for special meaning characters like \. to match a period or \+ for plus sign.
^ and $     ^ and $ match the start or end of the string respectively
{n,m}       Matches at least n and at most m occurrences of preceding expression if we write it as {,m} then
              it will return at least any minimum occurrence to max m preceding expression.
a| b        Matches either a or b
( )         Groups regular expressions and returns matched text
\t, \n, \r 	Matches tab, newline, return

# https://pythonspot.com/regular-expressions/
Regex     Description
\d 	      Matches any decimal digit; this is equivalent to the class [0-9]
\D 	      Matches any non-digit character; this is equivalent to the class [^0-9].
\s 	      Matches any whitespace character; this is equivalent to the class [ \t\n\r\f\v].
\S 	      Matches any non-whitespace character; this is equivalent to the class [^ \t\n\r\f\v].
\w 	      Matches any alphanumeric character; this is equivalent to the class [a-zA-Z0-9_].
\W 	      Matches any non-alphanumeric character; this is equivalent to the class [^a-zA-Z0-9_].
\Z 	      Matches only at end of string
[..]      Match single character in brackets
[^..]     Match any single character not in brackets
. 	      Match any character except newline
$ 	      Match the end of the string
* 	      Match 0 or more repetitions
+ 	      1 or more repetitions
{m}       Exactly m copies of the previous RE should be matched.
| 	      Match A or B. A|B
? 	      0 or 1 repetitions of the preceding RE
[a-z]     Any lowercase character
[A-Z]     Any uppercase character
[a-zA-Z]  Any character
[0-9]     Any digit 

Example 	      Regex
IP address 	    (([2][5][0-5]\.)|([2][0-4][0-9]\.)|([0-1]?[0-9]?[0-9]\.)){3}(([2][5][0-5])|([2][0-4][0-9])|([0-1]?[0-9]?[0-9]))
Email 	        [^@]+@[^@]+\.[^@]+
Date MM/DD/YY 	(\d+/\d+/\d+)
Integer(+)      (?
Integer         [+-]?(?
Float           (?<=>)\d+.\d+|\d+
Hexadecimal     \s–([0-9a-fA-F]+)(?:–)?\s