Modifiers

The operators in Table 10-9 modify the way other operators are interpreted.

Table 10-9. Regular expression modifiers

Basic regular expression

Extended regular expression

Description

*
*

Match zero or more of the character that precedes it.

\?
?

Match zero or one instance of the preceding regex.

\+
+

Match one or more instances of the preceding regex.

\{n,m\}
{n,m}

Match a range of occurrences of the single character or regex that precedes this construct. \{n\} matches n occurrences, \{n,\} matches at least n occurrences, and \{n,m\} matches any number of occurrences between n and m, inclusively.

\|
|

Match the character or expression to the left or right of the vertical bar.

\(regex\)
(regex)

Matches regex, but it can be modified as a whole and used in back-references. (\1 expands to the contents of the first \(\) and so on up to \9.)

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