PHP PCRE Cheat Sheet

As a first thought this post isn’t meant to be a super complete explanation of all the characters, quantifiers, modifiers of the regular expression world, neither it is a tutorial on how to use them.

This is just a cheat sheet of the, in my opinion, most used features of the complex world of regex.

PHP Regex Cheat Sheet

Base Chars		Meta Chars
\w	Same as (a-z0-9_)	^	Start of line/string
\W	Any non word characters	$	end of line/string
\s	Any whitespace chars	[	Start chars class
\S	Any non whitespace character	]	End char class
\d	All digits	|	Or (x|y) x or y
\D	Non digit chars	(	Start subpattern
\b	Word boundary	)	End subpattern
\B	Not word boundary	\	Escape char
.	Any character

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Quantifiers		Modifiers
*	Zero or more	i	Ignore case
+	One or more	m	Multiline mode ^ and $ match start/end of line
?	Zero or one	s	.* will include newline char
{n}	Exactly n	S	Extra analysis of pattern (optimize reuse)
{n,}	At least n	U	Ungreedy
{,m}	At most m	u	Treat as UTF-8
{n,m}	From n to m		more about modifiers

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PHP Functions
preg_match(pattern, subject[, submatches])
preg_match_all(pattern, subject[, submatches])
preg_replace(pattern, replacement, subject)
preg_replace_callback(pattern, callback, subject)
preg_grep(pattern, array)
preg_split(pattern, subject)

For a much more detailed documentation visit: PHP: PCRE Patterns