regex.md

regular expressions

Characters

symbol	description	remark
.	any character
\d	one digit character	0-9
\w	one word character	letter, digit or underscore
\s	one whitespace character	space, tab, etc.
\D	character that is no digit character
\W	character that is no word character
\S	character that is no whitespace character
\	escape a special character	\., etc.

Special Characters

symbol	description	remark
\t	tab
\r	carriage return
\n	line feed

Characters Classes

symbol	description	remark
[...]	one of the characters in the brackets	[ABC] means one character A, B, or C
-	range indicator	[0-5] means one character from 0 to 5

Quantifiers

symbol	description	remark
?	one or none (optional)
*	zero or more times
+	one or more times
{3}	exactly three times
{2,4}	two to four times
{3,}	three or more times

Logic

symbol	description	remark
|	or operand	A|B means one character that is A or B
[^]	not operand	[^x] is one character that is no x
(...)	define a group	groups are numbered from left to right
\2	repeat the content of group 2

Anchors

symbol	description	remark
^	start of string or start of line (only outsinde if [], inside it means not)	^The matches any string that starts with 'The'
$	end of string or end of line	end$ matches any string that ends with 'end'