A Perl quote-like operator used to delimit a regular expression (RE) like "?FOO?" that matches FOO at most once. The normal "/FOO/" form of regular expression will match FOO any number of times. The "??" operator will match again after a call to the "reset" operator.

The operator is usually referred to as "??" but, taken literally, an empty RE like this (or "//") actually means to re-use the last successfully matched regular expression or, if there was none, empty string (which will always match).

Unix manual page: perlop(1).

Last updated: 2009-05-28

Nearby terms:

<g><gr&d>=>???@@-party@Begin@stake@XX[incr Tcl]

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