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Regular Expressions

Table A-6 lists regular expressions in Ruby.

Table A-6. Regular expressions in Ruby

Pattern

Description

/pattern/options

Pattern pattern in slashes, followed by optional options, one or more of: i for case-insensitive; o for substitute once; x for ignore whitespace, allow comments; m for match multiple lines and newlines as normal characters.

%r!pattern!

General delimited string for a regular expression, where ! can be an arbitrary character.

^

Matches beginning of line.

$

Matches end of line.

.

Matches any character.

\1...\9

Matches nth grouped subexpression.

\10

Matches nth grouped subexpression if already matched; otherwise, refers to octal representation of a character code.

\n, \r, \t, etc.

Matches character in backslash notation.

\w

Matches word character; same as [0-9A-Za-z_].

\W

Matches nonword character; same as [^0-9A-Za-z_].

\s

Matches whitespace character; same as [\t\n\r\f].

\S

Matches nonwhitespace character; same as [^\t\n\r\f].

\d

Matches digit; same as [0-9].

\D

Matches nondigit; same as [^0-9].

\A

Matches beginning of a string.

\Z

Matches end of a string, or before newline at the end.

\z

Matches end of a string.

\b

Matches word boundary outside [] or backspace (0x08) inside [].

\B

Matches nonword boundary.

\G

Matches point where last match finished.

[..]

Matches any single character in brackets, such as [ch].

[^..]

Matches any single character not in brackets.

*

Matches zero or more of previous regular ...

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