Regular Expressions - Revision history

Hdridder at 14:24, 7 July 2025

2025-07-07T14:24:55Z

← Older revision		Revision as of 14:24, 7 July 2025
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	{\| class="wikitable"		{\| class="wikitable"
	\|-		\|-
	\|.\|\|Any character except newline (POSIX)\|\|\c\|\|Control character		\|.\|\|Any character except newline (POSIX)\|\|\c\|\|Control character (not for Python3)
	\|-		\|-
	\|\d\|\|Digit\|\|\D\|\|non Digit		\|\d\|\|Digit\|\|\D\|\|non Digit
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	\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy) (POSIX)\|\|{x,y}\|\|Match the previous expression between x an y times.<br>When y is ommited match exactly x times (POSIX)		\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy) (POSIX)\|\|{x,y}\|\|Match the previous expression between x an y times.<br>When y is ommited match exactly x times (POSIX)
	\|-		\|-
	\|<nowiki>\n</nowiki>\|\|Refers to the ~~Nth~~ subexpression (POSIX)~~\|\| \|\|~~		\|<nowiki>\n</nowiki>\|\|Newline\|\|<nowiki>\<int></nowiki>\|\|Refers to the <int>-th subexpression (POSIX)
	\|}		\|}

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	==Python==		==Python==
	Check [[Python:Strings#Regular_Expressions_(regexp)]]		Check [[Python:Strings#Regular_Expressions_(regexp)]] and/or the [https://cheatography.com/mutanclan/cheat-sheets/python-regular-expression-regex/ cheatography site]

Hdridder at 11:33, 14 June 2022

2022-06-14T11:33:30Z

← Older revision		Revision as of 11:33, 14 June 2022
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	\|}		\|}

			==Examples==
			;<code>/[^/]*$</code>
			:Match last / and everything following

	==Perl==		==Perl==

Hdridder at 11:00, 3 June 2021

2021-06-03T11:00:02Z

← Older revision		Revision as of 11:00, 3 June 2021
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	Regular expressions or regexp are used to find strings in text.		Regular expressions or regexp are used to find strings in text.

			[[Perl]], [[PHP]] and [[Python]] support all in below table. [[:Category:Bash\|Bash]] and [[SQL]] only support the POSIX part.

	{\| class="wikitable"		{\| class="wikitable"
	\|-		\|-
	\|.\|\|Any character except newline\|\|\c\|\|Control character		\|.\|\|Any character except newline (POSIX)\|\|\c\|\|Control character
	\|-		\|-
	\|\d\|\|Digit\|\|\D\|\|non Digit		\|\d\|\|Digit\|\|\D\|\|non Digit
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	\|\w\|\|Word character [A-Za-z0-9]\|\|\W\|\|non Word character		\|\w\|\|Word character [A-Za-z0-9]\|\|\W\|\|non Word character
	\|-		\|-
	\|^\|\|Start of string\|\|$\|\|End of string		\|^\|\|Start of string (POSIX)\|\|$\|\|End of string (POSIX)
	\|-		\|-
	\|*\|\|0 or more matches of previous expression\|\|( )\|\|Subexpression		\|*\|\|0 or more matches of previous expression (POSIX)\|\|( )\|\|Subexpression (POSIX)
	\|-		\|-
	\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match any of the characters between the [ ].<br>^as first character negates the match		\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression (POSIX)\|\|[ ]\|\|Match any of the characters between the [ ].<br>^as first character negates the match (POSIX)
	\|-		\|-
	\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)\|\|{x,y}\|\|Match the previous expression between x an y times.<br>When y is ommited match exactly x times		\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy) (POSIX)\|\|{x,y}\|\|Match the previous expression between x an y times.<br>When y is ommited match exactly x times (POSIX)
			\|-
			\|<nowiki>\n</nowiki>\|\|Refers to the Nth subexpression (POSIX)\|\| \|\|
	\|}		\|}

Hdridder: /* Python */

2020-11-11T15:24:37Z

Python

← Older revision		Revision as of 15:24, 11 November 2020
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	==Python==		==Python==
	Check [[Python:Strings#~~Regular_Expressions~~]]		Check [[Python:Strings#Regular_Expressions_(regexp)]]

Hdridder at 15:22, 11 November 2020

2020-11-11T15:22:16Z

← Older revision		Revision as of 15:22, 11 November 2020
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	\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match any of the characters between the [ ].<br>^as first character negates the match		\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match any of the characters between the [ ].<br>^as first character negates the match
	\|-		\|-
	\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)		\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)\|\|{x,y}\|\|Match the previous expression between x an y times.<br>When y is ommited match exactly x times
	\|}		\|}

Hdridder at 18:52, 29 August 2018

2018-08-29T18:52:07Z

← Older revision		Revision as of 18:52, 29 August 2018
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	\|*\|\|0 or more matches of previous expression\|\|( )\|\|Subexpression		\|*\|\|0 or more matches of previous expression\|\|( )\|\|Subexpression
	\|-		\|-
	\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match ~~anything~~ between the [ ].<br>^as first character negates the match		\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match any of the characters between the [ ].<br>^as first character negates the match
	\|-		\|-
	\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)		\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)

Hdridder: /* Perl */

2018-07-09T13:08:36Z

Perl

← Older revision		Revision as of 13:08, 9 July 2018
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	;@array = $var =~ m/<pattern>/g;		;@array = $var =~ m/<pattern>/g;
	:Put all matches of <pattern> in var into @array		:Put all matches (or all first submatches) of <pattern> in var into @array

	Following variables are when a match is made:		Following variables are when a match is made:

Hdridder: /* Perl */

2018-07-09T12:34:02Z

Perl

← Older revision		Revision as of 12:34, 9 July 2018
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	;$var =~ /<pattern>/		;$var =~ /<pattern>/
	:Generic syntax, this expression is true if the pattern is matched in $var		:Generic syntax, this expression is true if the pattern is matched in $var

			;@array = $var =~ m/<pattern>/g;
			:Put all matches of <pattern> in var into @array

	Following variables are when a match is made:		Following variables are when a match is made:
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	&& ($rev = $+);		&& ($rev = $+);
	</syntaxhighlight>		</syntaxhighlight>

	==Python==		==Python==
	Check [[Python:Strings#Regular_Expressions]]		Check [[Python:Strings#Regular_Expressions]]

Hdridder at 09:56, 15 May 2018

2018-05-15T09:56:44Z

← Older revision		Revision as of 09:56, 15 May 2018
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			Regular expressions or regexp are used to find strings in text.

	{\| class="wikitable"		{\| class="wikitable"
	\|-		\|-
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	==Perl==		==Perl==

			;perl -lne 'print $1 if (/<regexp(subexp)>/)'
			:Commandline to print the first subexp in a match.

	;$var =~ /<pattern>/		;$var =~ /<pattern>/

Hdridder at 08:00, 14 March 2018

2018-03-14T08:00:47Z

← Older revision		Revision as of 08:00, 14 March 2018
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	\|^\|\|Start of string\|\|$\|\|End of string		\|^\|\|Start of string\|\|$\|\|End of string
	\|-		\|-
	\|*\|\|0 or more matches of previous expression		\|*\|\|0 or more matches of previous expression\|\|( )\|\|Subexpression
	\|-		\|-
	\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression		\|<nowiki>+</nowiki>\|\|1 or more matches of previous expression\|\|[ ]\|\|Match anything between the [ ].<br>^as first character negates the match
	\|-		\|-
	\|<nowiki>?</nowiki>\|\|0 or 1 matches ~~(optional)~~. Stop search		\|<nowiki>?</nowiki>\|\|0 or 1 matches of previous expression.<br>Stop search as soon as next expression is found (non greedy)
	as soon as next expression is found (non greedy)
	\|}		\|}

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	:The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already.		:The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already.
	;$'		;$'
	:The string following whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ~~For example~~:		:The string following whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already.<br>Example:
	<syntaxhighlight lang=perl>		<syntaxhighlight lang=perl>
	$_ = 'abcdefghi';		$_ = 'abcdefghi';
	/def/;		/def/;
	print "$`:$&:$'n";		print "$`:$&:$'";
	# prints abc:def:ghi		# prints abc:def:ghi
	</syntaxhighlight>		</syntaxhighlight>

			;$1
			:String matched by the first subexpression.

	;$+		;$+
	:The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched. ~~For example~~:		:The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.<br>Example:
	<syntaxhighlight lang=perl>		<syntaxhighlight lang=perl>
	/Version: (.)\|Revision: (.)/		/Version: (.)\|Revision: (.)/