Regular Expression Reference on a Mouse Mat * Regex Training
POSIX details * Perl details * Java details

Visual Basic, C++ and C# amongst other languages can make use of the shared regular expression library provided under Microsoft's .NET framework. The library is uses Perl-flavoured regular expressions, but with some subtle variations.

Operator Type	Examples	Description
Literal Characters Match a character exactly	a A y 6 % @	Letters, digits and many special characters match exactly
	\$ \^ \+ \\ \?	Precede other special characters with a \ to cancel their regex special meaning
	\n \t \r	Literal new line, tab, return
	\cJ \cG	Control codes
	\xa3	Hex codes for any character
	\u00a3	Unicode for any character
Anchors and assertions	^	Starts with
	$	Ends with
	\b \B	on a word boundary, NOT on a word boundary
Character groups any 1 character from the group	[aAeEiou]	any character listed from [ to ]
	[^aAeEiou]	any character except aAeEio or u
	[a-fA-F0-9]	any hex character (0 to 9 or a to f)
	.	any character at all (not new line in some circumstances)
	\s	any space character (space \n \r or \t)
	\w	any word character (letter digit or _)
	\d	any digit (0 through 9)
	\S \W \D	any character that is NOT a space word character or digit
Counts apply to previous element	+	1 or more ("some")
	*	0 or more ("perhaps some")
	?	0 or 1 ("perhaps a")
	{4}	exactly 4
	{4,}	4 or more
	{4,8}	between 4 and 8
	Add a ? after any count to turn it sparse (match as few as possible) rather than have it default to greedy
Alternation	|	either, or
Grouping	( )	group for count and save to variable
	(?: )	group for count but do not save

Option modes can be specified as using a (?x ) if you wish them to cover part of the regular expression, or as per the following table if you want them to apply to the whole of a regular expression:

Option	Description
.IgnoreCase	Ignore case in matching
.IgnorePatternWhiteSpace	White space is to be treated as a comment (otherwise it matches exactly)
.Singleline	. to match everything including new line (otherwise it matches everything except new line)
.Multiline	^ and $ to match embedded new lines

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