Regular expression - Revision history

DavidB4-bot: clean up

2016-06-23T15:04:41Z

clean up

JonG: removed extra lines. formatting was retained.

2011-09-03T21:53:22Z

removed extra lines. formatting was retained.

Aschlafly: Reverted edits by WWFY (talk) to last revision by WilliamMoran

2011-09-03T21:33:47Z

Reverted edits by WWFY (talk) to last revision by WilliamMoran

WWFY: better maybe?

2011-09-03T21:32:35Z

better maybe?

WilliamMoran: added insight

2011-09-03T21:32:31Z

added insight

WWFY: fix

2011-09-03T21:31:36Z

fix

Ed Poor: I disagree with this emample. Who wrote this article?

2010-02-08T22:51:52Z

I disagree with this emample. Who wrote this article?

Ed Poor: trying to make this article less lame

2010-02-08T22:50:46Z

trying to make this article less lame

Ed Poor: matched from left to right and is processed one token at a time

2010-02-08T22:46:31Z

matched from left to right and is processed one token at a time

Ed Poor: a pattern describing a certain amount of text.

2010-02-08T22:46:01Z

a pattern describing a certain amount of text.

@@ Line 1: / Line 1: @@
-A '''regular expression''' is used in computer software to define a sequence of characters.<ref>"A regular expression, or regex for short, is a pattern describing a certain amount of text." [http://www.regular-expressions.info/quickstart.html Regular Expression Quick Start] </ref>
+A '''regular expression''' is used in computer software to define a sequence of characters.<ref>"A regular expression, or regex for short, is a pattern describing a certain amount of text." [http://www.regular-expressions.info/quickstart.html Regular Expression Quick Start]</ref>
 In general, any character will match itself, but there are a dozen special characters, including the [[escape character]].
-To match any of 2 or more characters, enclose them in square brackets. For example, <br /><br /> gr[ae]y
+To match any of 2 or more characters, enclose them in square brackets. For example,
-<br /><br /> will match ''gray'' or ''grey''.
 A regular expression is matched from left to right and is processed one [[token]] at a time.  Certain characters have special meanings within the description of a regular language:
@@ Line 34: / Line 38: @@
 A '''regular expression''' is particular instance of a non-[[deterministic]] [[finite]] state [[automaton]].  Regular expressions are a [[type-3 grammar]] in the [[Chomsky hierarchy]] of [[language]].
-A regular expression is not able to count.  This is because there is a finite number of states.  Consider the language that is specified by a<sup><small>n</small></sup>ba<sup><small>n</small></sup>.  Examples of this language include b, aba, aabaa, aaabaaa, etc... A regular expression - being a [[finite state automaton]] itself - has a finite number of states that it can be in.  If there a point at which the state loops back on itself it is no longer able to match that language.
+A regular expression is not able to count.  This is because there is a finite number of states.  Consider the language that is specified by a<sup>n</sup>ba<sup>n</sup>.  Examples of this language include b, aba, aabaa, aaabaaa, etc... A regular expression - being a [[finite state automaton]] itself - has a finite number of states that it can be in.  If there a point at which the state loops back on itself it is no longer able to match that language.
 == See also ==
@@ Line 45: / Line 49: @@
 <references/>
 [[Category:Computer Science]]
-[[Category:language]]
+[[Category:Language]]

@@ Line 3: / Line 3: @@
 In general, any character will match itself, but there are a dozen special characters, including the [[escape character]].
-To match any of 2 or more characters, enclose them in square brackets. For example,
+To match any of 2 or more characters, enclose them in square brackets. For example, <br /><br /> gr[ae]y
-<br /><br /> gr[ae]y
+<br /><br /> will match ''gray'' or ''grey''.
 A regular expression is matched from left to right and is processed one [[token]] at a time.  Certain characters have special meanings within the description of a regular language:

@@ Line 25: / Line 25: @@
 Regular expressions have also been extended by many languages, some of which extend them to the point where they are able to match a wider range of languages than is specified by a regular language.
-<references/>
 == Examples ==
@@ Line 45: / Line 45: @@
 == Further reading ==
 * http://www.regular-expressions.info/reference.html
 [[Category:Computer Science]]
 [[Category:language]]

@@ Line 25: / Line 25: @@
 Regular expressions have also been extended by many languages, some of which extend them to the point where they are able to match a wider range of languages than is specified by a regular language.
+<references/>
 == Examples ==
@@ Line 45: / Line 45: @@
 == Further reading ==
 * http://www.regular-expressions.info/reference.html
 [[Category:Computer Science]]
 [[Category:language]]

@@ Line 4: / Line 4: @@
 To match any of 2 or more characters, enclose them in square brackets. For example,
+<br /><br /> gr[ae]y
- gr[ae]y
+<br /><br />
 will match ''gray'' or ''grey''.

@@ Line 29: / Line 29: @@
 == Examples ==
 * /Mrs?\. Smith/ - matches 'Mr. Smith', 'Mrs. Smith'
 * /^a*b*$/ - matches 'a', 'ab', 'b', 'aaaab', 'abbbbb', 'aaabbb', ''

← Older revision		Revision as of 22:46, February 8, 2010
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		+	A '''regular expression''' is used in computer software to define a sequence of characters.<ref>"A regular expression, or regex for short, is a pattern describing a certain amount of text." [http://www.regular-expressions.info/quickstart.html Regular Expression Quick Start] </ref>
		+
	A regular expression is read from left to right and is processed one piece at a time. Certain characters have special meanings within the description of a regular language:		A regular expression is read from left to right and is processed one piece at a time. Certain characters have special meanings within the description of a regular language:
	* '*' - the previous construction is matched 0 or more times		* '*' - the previous construction is matched 0 or more times