@H_403_6@Symbols

@H_403_6@literal

@H_403_6@Match literal string valueliteral

@H_403_6@foo

@H_403_6@re1|re2

@H_403_6@Match regular expressionsre1 or re2

@H_403_6@foo|bar

.

Matchany character (except NEWLINE)

b.b

^

Match start of string

^Dear

$

Match end of string

/bin/*sh$

*

Match 0 or more occurrences of preceding RE

[A-Za-z0-9]*

+

Match 1 or more occurrences of preceding RE

[a-z]+\.com

?

Match 0 or 1 occurrence(s) of preceding RE

goo?

{N}

Match N occurrences of preceding RE

[0-9]{3}

{M,N}

Match from M to N occurrences of preceding RE

[0-9]{5,9}

[...]

Match any single character fromcharacter class

[aeIoU]

[..x-y..]

Match any single character in therange fromx to y

[0-9],[A-Za-z]

[^...]

Do not match any character from character class,including any ranges,if present

[^aeIoU],[^A-Za-z0-9_]

@H_403_6@(*|+|?| {})?

@H_403_6@Apply "non-greedy" versions of above occurrence/repetition symbols (*,+,?,{})

@H_403_6@.*?[a-z]

@H_403_6@(...)

@H_403_6@Match enclosed RE and save assubgroup

@H_403_6@([0-9]{3})?,f(oo|u)bar

@H_403_6@Special Characters

\d

Match any decimal digit,same as [0-9](\D is inverse of \d: do not match any numeric digit)

data\d+.txt

\w

Match any alphanumeric character,same as [A-Za-z0-9_] (\W is inverse of\w)

[A-Za-z_]\w+

\s

Match any whitespace character,same as [ \n\t\r\v\f] (\S is inverse of\s)

of\sthe

@H_403_6@\b

@H_403_6@Match any word boundary (\B is inverse of \b)

@H_403_6@\bThe\b

\nn

Match saved subgroup nn (see (...) above)

price: \16

\c

Match any special character c verbatim (i.e.,with out its special meaning,literal)

\.,\\,\*

@H_403_6@\A (\Z)

@H_403_6@Matchstart (end) of string (also see ^ and $ above)

@H_403_6@\ADear