Regular Expressions

\n matches a new-line character

* equals {0,}

zo* matches z and zoo

+ equals {1,}.

? equals {0,1}

colou?r matches color or colour but not colouur

do(es)? matches the do in do or does

o{2,} does not match the o in Bob, but matches the two os in food

b{4,} matches bbbb

o{2} does not match the o in Bob and matches all the os in foooood

o{1} is equivalent to o+

o{0} is equivalent to o*

Note: You cannot put a space between the comma and the numbers.

o{1,3} matches the first three os in fooooood

o{0,1} is equivalent to o?

c{2, 4} matches cc, ccc, cccc

To match any character including the '\n', use a pattern such as '[\s\S]'.

To match parentheses characters ( ), use '\(' or '\)'.

First group matches jam

This is useful for combining parts of a pattern with the "or" character (|).

Lookaheads do not consume characters: after a match occurs, the search for the next match begins immediately following the last match, not after the characters that comprised the lookahead.

Lookaheads do not consume characters, that is, after a match occurs, the search for the next match begins immediately following the last match, not after the characters that comprised the lookahead.

z|food matches z or food

( z|f)ood matches zood or food

[abc] matches the a in plain

[^abc] matches the p in plain

[a-z] matches any lowercase alphabetic character in the range a through z

Matches any character not in the specified range.

The value of x must be in the range of A-Z or a-z.

If not, c is assumed to be a literal 'c' character.

Equivalent to [0-9]

Equivalent to [^0-9]

Equivalent to \x0c and \cL

Equivalent to \x0a and \cJ

Equivalent to \x0d and \cM

Equivalent to [\f\n\r\t\v]

Equivalent to [^\f\n\r\t\v]

Equivalent to \x09 and \cI

Equivalent to \x0b and \cK

Equivalent to '[A-Za-z0-9_]'

Equivalent to '[^A-Za-z0-9_]'

You should only use \D, \W and \S outside character classes.

Hexadecimal escape values must be exactly two digits long.

Allows ASCII codes to be used in regular expressions.

\x041 is equivalent to \x04 and 1

A reference back to captured matches.

If \n is preceded by at least n captured sub-expressions, n is a back-reference.

Otherwise, n is an octal escape value if n is an octal digit (0-7).

\0011 is the equivalent of 1

If \nm is preceded by at least nm captured sub-expressions, nm is a back-reference.

If \nm is preceded by at least n captures, n is a back-reference followed by literal m.

If neither of the preceding conditions exists, \nm matches octal escape value nm when n and m are octal digits (0-7).