Regular expression quick start guide

From TBwiki

(Difference between revisions)

Revision as of 17:22, 26 January 2010

Regular Expression Pattern	Explanations
^	Matches beginning of a line
$	Matches the end of a line
\d	Matches a digit
[characters]	Matches any single character between the brackets
re1\|re2	Match either re1 or re2
re*	Matches zero or more occurrences of re
re+	Matches one or more occurrences of re
re?	Matches zero or one occurrences of re
Re{m,n}	Matches at least “m” and at most “n” occurrences of re
(...)	Parentheses are used to group regular expressions
\0, \1, \2, ...	Substitute the value matched by the nth grouped sub-expression, used in remapped fields.

Here are some examples:

Add 2720 prefix:

/(\d+)/2720\1/

or

/([0-9]*)/2720\1/

Strip first 4 digits:

/([0-9]{4})([0-9]*)/\2/

Strip # and 7 first digits:

/([#])([0-9]{7})([0-9]*)/\3/

@@ Line 1: / Line 1: @@
-== Quick Reference Table<br> ==
+== Quick Reference Table<br>  ==
 {| cellpadding="2" border="1"
@@ Line 40: / Line 40: @@
 |}
 <br>
-== Quick References ==
+== Quick References  ==
-=== Text Patterns and Matches<br> ===
+=== Text Patterns and Matches<br>  ===
 <br>
-=== Literal Characters<br> ===
+=== Literal Characters<br>  ===
 <br>
-=== Character Classes or Character Sets<br> ===
+=== Character Classes or Character Sets<br>  ===
 <br>
-=== Shorthand Character Classes<br> ===
+=== Shorthand Character Classes<br>  ===
 <br>
-=== The Dot Matches (Almost) Any Character<br> ===
+=== The Dot Matches (Almost) Any Character<br>  ===
 <br>
-=== Repetition<br> ===
+=== Repetition<br>  ===
 <br>
-=== Optional<br> ===
+=== Optional<br>  ===
 <br>
-=== Anchors<br> ===
+=== Anchors<br>  ===
 <br>
-=== Alternation<br> ===
+=== Alternation<br>  ===
 <br>
-=== Grouping and Capturing Group<br> ===
+=== Grouping and Capturing Group<br>  ===
 <br>
-== Examples<br> ==
+== Examples<br>  ==
 Here are some examples:
@@ Line 104: / Line 104: @@
   /([#])([0-9]{7})([0-9]*)/\3/
-== Online Tools ==
+== Online Tools  ==
+*Regex builder tool :&nbsp;[http://www.gskinner.com/RegExr www.gskinner.com/RegExr]
+*Ruby regular expression editor and tester : [http://rubular.com rubular.com]
 == References  ==