Regular Expressions

Examples

Regular Expression Explanation
.*AbC.* matches data containg the phrase "AbC"
[Mm]y [Nn]ame matches data containg the phrase "My Name" independet of upper or lower case notation

Syntax of Regular Expressions

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
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
Variables $xyz Insert contents of $xyz into regular expression
\1 \2 Back reference to 1st, 2nd etc matched groups

Christoph Wieser
Last modified: Fri Sep 5 09:15:02 CEST 2003