Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 154

Table 4-19. The List of the Predefined Character Classes

Predefined
Character Classes

Meaning

. (a dot) Any character (may or may not match line terminators)

\d A digit. Same as [0-9]

\D A non-digit. Same as [^0-9]

\s A whitespace character. Same as [\t\n\x0B\f\r] . The list

includes a space, a tab, a new line, a vertical tab, a form feed,
and a carriage return characters

\S A non-whitespace character. Same as [^\s]

\w A word character. Same as [a-zA-Z_0-9] . The list includes

lowercase letters, uppercase letter, underscore, and
decimal digits

\W A nonword character. Same as [^\w]

You can also specify the number of times a character in a regular expression may
match the sequence of characters. If you want to match all two digit integers, the regular
expression would be /\d\d/ , which is the same as /[0-9][0-9]/ . What would be the
regular expression to match an integer? You cannot write the regular expression to match
an integer with the knowledge you have gained so far. You need to be able to express a
pattern “one digit or more” using a regular expression. Quantifiers and their meanings
have been listed in Table 4-20 .

Table 4-20. Quantifiers and Their Meanings

Quantifiers Meaning

* Zero or more times

+ One or more times

?

Once or not at all

{m} Exactly m times

{m, } At least m times

{m, n} At least m , but not more than n times