RegEx

Notes for RegEx respectively Regular Expressions and also some useful ressources.

General Rules

Character Types
Type	Example
Literal	a b c 1 2 3
Meta characters	. [[ ] { } ? * + \| ( ) ^ $

Meta Characters
Meta Character	Example
Single Character	.
Character class digit	\d
Character class character	\w
Character class whitespace (Space, tab, new line, carriage return)	\s
Inversion of character classes (Not)	\D, \W, \S
Word and text boundaries	b ^ $

Ranges and Groups
Range or Group	Example
Character class range	[a-c]
Inversion of character class range	[^abc]
Grouping with alternatives	(Mon\|Tues)day

Quantifiers
Quantifier	Example
Zero or one character	?
Zero or more characters (Kleene Star)	*
One or more characters (Kleene Plus)	+
Three characters	{3}
Four to 20 characters	{4,20}

Line start and end
Type	Example
Start of line	^
End of line	$

Groups and nested groups
Type	String	Expression	Results
Group Example 1	IMG1000.png	^(IMG\d+\.png)$	IMG1000.png
Group Example 2	IMG1000.png	^(IMG\d+)\.png$	IMG1000
Nested group	IMG1000.png	^(IMG(\d+))\.png$	Group 1: IMG1000 Group 2: 1000
Multiple groups	1920x1080	(\d+)x(\d+)	Group 1: IMG1000 Group 2: 1000