Perl regex - Revision history

Woozle: /* Links */ PHP PCRE functions

2009-07-16T13:34:15Z

Links: PHP PCRE functions

← Older revision		Revision as of 13:34, 16 July 2009
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	** $string =~ s\|^.\.([^\.])$\|$1\|;		** $string =~ s\|^.\.([^\.])$\|$1\|;
	==Links==		==Links==
			===Reference===
			* [http://php.net/pcre Regular Expressions (Perl-Compatible)] in [[PHP]]
			** PHP also supports [http://php.net/regex POSIX regex] via the [http://php.net/ereg ereg()] series of functions, but these are apparently deprecated; to convert code from ereg to PCRE, just add slashes around the string: /<u>regex expression</u>/
			===Articles===
	* '''2007-10-24''' [http://pugs.blogs.com/pugs/2007/10/a-graphical-tra.html A graphical tracer for Perl 6 regexes based on PCR]: code for a graphical regex tracer written in [[Perl 6]], with links to some demo sites		* '''2007-10-24''' [http://pugs.blogs.com/pugs/2007/10/a-graphical-tra.html A graphical tracer for Perl 6 regexes based on PCR]: code for a graphical regex tracer written in [[Perl 6]], with links to some demo sites

Woozle: /* Details */ alternate meaning for "?"

2007-12-24T15:25:42Z

Details: alternate meaning for "?"

← Older revision		Revision as of 15:25, 24 December 2007
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	* '''+''' = 1 or more of previous character		* '''+''' = 1 or more of previous character
	* '''?''' after '''+''', '''*''', or '''{}''' indicates non-greedy behavior, i.e. match the fewest characters, not the most		* '''?''' after '''+''', '''*''', or '''{}''' indicates non-greedy behavior, i.e. match the fewest characters, not the most
			** Apparently it can also mean "either zero or one of the preceding group or character", e.g. "the?" matches both "th" and "the"
	* <u>a</u>'''-'''<u>b</u> = range of characters from <u>a</u> to <u>b</u>, e.g. "t-w" means any of t,u,v,w in that position		* <u>a</u>'''-'''<u>b</u> = range of characters from <u>a</u> to <u>b</u>, e.g. "t-w" means any of t,u,v,w in that position
	* '''?=''' = lookahead (need explanation of how this works) <u>a</u>'''(?='''<u>b</u>''')''' returns "<u>a</u>, but only if it's followed by a <u>b</u>"; the <u>a</u> becomes part of the matched sequence, but the <u>b</u> does not		* '''?=''' = lookahead (need explanation of how this works) <u>a</u>'''(?='''<u>b</u>''')''' returns "<u>a</u>, but only if it's followed by a <u>b</u>"; the <u>a</u> becomes part of the matched sequence, but the <u>b</u> does not

Woozle: /* Examples */ links: graphical regex tracer

2007-11-05T19:21:51Z

Examples: links: graphical regex tracer

← Older revision		Revision as of 19:21, 5 November 2007
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	** $string =~ s\|^.+\.(.+$)\|$1\|;		** $string =~ s\|^.+\.(.+$)\|$1\|;
	** $string =~ s\|^.\.([^\.])$\|$1\|;		** $string =~ s\|^.\.([^\.])$\|$1\|;
			==Links==
			* '''2007-10-24''' [http://pugs.blogs.com/pugs/2007/10/a-graphical-tra.html A graphical tracer for Perl 6 regexes based on PCR]: code for a graphical regex tracer written in [[Perl 6]], with links to some demo sites

Woozle: updated navbar; sections for navbar & overview

2006-07-28T22:23:35Z

updated navbar; sections for navbar & overview

← Older revision		Revision as of 22:23, 28 July 2006
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	[[~~Computing~~]]: [[~~Programming~~]]: [[Perl]]: [[Perl regex\|regex]]		=={{hide\|Navbar}}==
			[[computing]]: [[programming]]: [[Perl]]: [[Perl regex\|regex]]
			==Overview==
	This article explains regular expressions in terms understandable to mere mortals, and also how to use them in Perl.		This article explains regular expressions in terms understandable to mere mortals, and also how to use them in Perl.
	==Related Articles==		==Related Articles==
	*{{manpagelink\|regex}}: manpage documentation		*{{manpagelink\|regex}}: manpage documentation

	==Details==		==Details==
	Special characters in regex:		Special characters in regex:

Woozle: /* Details */ more stuff, and how to match everything-including-newline

2006-07-17T20:18:05Z

Details: more stuff, and how to match everything-including-newline

← Older revision		Revision as of 20:18, 17 July 2006
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	==Details==		==Details==
	Special characters in regex:		Special characters in regex:
	* '''.''' = any character except newline (\n) (~~'''Questions''':~~ is ~~there any special character which represents ''all'' characters? Does [.] also mean any-character-except-newline~~, or is ~~it interpreted as literal period?~~)		* '''.''' = any character except newline (\n) (if /s option is included, then \n is also matched)
	* '''*''' = 0 or more of previous character		* '''*''' = 0 or more of previous character
	* '''^''' = following string begins the line (except [^...] means "not these characters")		* '''^''' = following string begins the line (except [^...] means "not these characters")
	* '''$''' = preceding string ends the line		* '''$''' = preceding string ends the line
	* '''[]''' = list of characters which can satisfy the match at this position		* '''[]''' = list of characters which can satisfy the match at this position
			** Note: cannot use special characters like "." as part of list
	* '''{}''' = # of repetitions of previous character:		* '''{}''' = # of repetitions of previous character:
	** {<u>x</u>} -> exactly <u>x</u> repetitions		** {<u>x</u>} -> exactly <u>x</u> repetitions
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	* '''=~''' returns TRUE if pattern matches		* '''=~''' returns TRUE if pattern matches
	* '''!~''' returns FALSE if pattern matches		* '''!~''' returns FALSE if pattern matches
			* '''m/''' searches a string for a pattern match; returns true/false scalar and an array of matches (if () are used)
			** '''c''' don't reset pos on failed matches when using /g
			** '''g''' ('''G'''lobal) all occurrences – repeat the pattern search until there are no more matches
			** '''i''' case-'''I'''nsensitive
			** '''m''' '''M'''ultiline mode - ^ and $ match internal lines
			** '''o''' compile pattern '''O'''nce
			** '''s''' match as a '''S'''ingle line - . (dot) matches \n
			** '''x''' e'''X'''tended legibility - free whitespace and comments
	* '''s/'''<u>pattern</u>'''/'''<u>replacement</u>'''/'''''gi''; replaces ''pattern'' with ''replacement''		* '''s/'''<u>pattern</u>'''/'''<u>replacement</u>'''/'''''gi''; replaces ''pattern'' with ''replacement''
	** '''g''' ~~(global) means repeat the pattern search until there are no more matches~~		** all m/ options are available
	** '''i''' (~~insensitive~~) ~~means alphabetic matches are checked case-insensitively~~		** '''e''' '''E'''valuate replacement as an expression. May be specified multiple times. 'replacement' is interpreted as a double quoted string unless a single-quote (') is the delimiter.
	* '''y/'''<u>searchlist</u>'''/'''<u>replacelist</u>'''/'''''d'': replaces each character found in <u>searchlist</u> with the corresponding character in <u>replacelist</u>		* '''y/'''<u>searchlist</u>'''/'''<u>replacelist</u>'''/'''''d'': replaces each character found in <u>searchlist</u> with the corresponding character in <u>replacelist</u>
	** '''d''' just deletes matching characters		** '''d''' just deletes matching characters

Woozle: /* Details */ more about dot

2006-07-17T18:27:27Z

Details: more about dot

← Older revision		Revision as of 18:27, 17 July 2006
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	==Details==		==Details==
	Special characters in regex:		Special characters in regex:
	* '''.''' = any character		* '''.''' = any character except newline (\n) ('''Questions''': is there any special character which represents ''all'' characters? Does [.] also mean any-character-except-newline, or is it interpreted as literal period?)
	* '''*''' = 0 or more of previous character		* '''*''' = 0 or more of previous character
	* '''^''' = following string begins the line (except [^...] means "not these characters")		* '''^''' = following string begins the line (except [^...] means "not these characters")

Woozle: /* Related Articles */ revised link

2006-04-12T18:21:58Z

Woozle: /* Examples */ more examples & variants

2006-04-05T22:16:09Z

Examples: more examples & variants

Show changes

Woozle: /* Details */ lookaheads

2006-03-29T22:30:27Z

Details: lookaheads

← Older revision		Revision as of 22:30, 29 March 2006
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	* '''?''' after '''+''', '''*''', or '''{}''' indicates non-greedy behavior, i.e. match the fewest characters, not the most		* '''?''' after '''+''', '''*''', or '''{}''' indicates non-greedy behavior, i.e. match the fewest characters, not the most
	* <u>a</u>'''-'''<u>b</u> = range of characters from <u>a</u> to <u>b</u>, e.g. "t-w" means any of t,u,v,w in that position		* <u>a</u>'''-'''<u>b</u> = range of characters from <u>a</u> to <u>b</u>, e.g. "t-w" means any of t,u,v,w in that position
			* '''?=''' = lookahead (need explanation of how this works) <u>a</u>'''(?='''<u>b</u>''')''' returns "<u>a</u>, but only if it's followed by a <u>b</u>"; the <u>a</u> becomes part of the matched sequence, but the <u>b</u> does not
			* '''?<=''' = reverse lookahead (need explanation of how this works)

	Operators used to invoke regex:		Operators used to invoke regex:

Woozle: /* Details */ more info from tene

2006-03-29T22:07:10Z

Details: more info from tene

← Older revision		Revision as of 22:07, 29 March 2006
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	==Details==		==Details==
	Special characters in regex:		Special characters in regex:
	* . = any character		* '''.''' = any character
	* * = 0 or more of previous character		* '''*''' = 0 or more of previous character
	* ^ = following string begins the line (except [^...] means "not these characters")		* '''^''' = following string begins the line (except [^...] means "not these characters")
	* $ = preceding string ends the line		* '''$''' = preceding string ends the line
	* [] = list of characters which can satisfy the match at this position		* '''[]''' = list of characters which can satisfy the match at this position
	* {} = # of repetitions of previous character		* '''{}''' = # of repetitions of previous character:
	* \| = alternatives		** {<u>x</u>} -> exactly <u>x</u> repetitions
	* + = 1 or more of previous character		** {<u>x</u>,<u>y</u>} -> minimum of <u>x</u> repetitions, maximum of <u>y</u> repetitions
	* ''a''-''b'' ~~= range of characters from~~ ''a'' to ''b'' ~~(must be inside []~~ to be position~~-sensitive?)~~		* '''\|''' = alternatives
			* '''+''' = 1 or more of previous character
			* '''?''' after '''+''', '''*''', or '''{}''' indicates non-greedy behavior, i.e. match the fewest characters, not the most
			* <u>a</u>'''-'''<u>b</u> = range of characters from <u>a</u> to <u>b</u>, e.g. "t-w" means any of t,u,v,w in that position

	Operators used to invoke regex:		Operators used to invoke regex:

← Older revision		Revision as of 18:21, 12 April 2006
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	This article explains regular expressions in terms understandable to mere mortals, and also how to use them in Perl.		This article explains regular expressions in terms understandable to mere mortals, and also how to use them in Perl.
	==Related Articles==		==Related Articles==
	*[[regex]]: manpage documentation		*{{manpagelink\|regex}}: manpage documentation

	==Details==		==Details==
	Special characters in regex:		Special characters in regex: