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Re: What does this statement do?

by linuxer (Curate)
on Jun 10, 2010 at 22:56 UTC ( #844141=note: print w/ replies, xml ) Need Help??

in reply to What does this statement do?

The regular expression can be explained, e.g.:

perl -MYAPE::Regex::Explain -wle ' my $re = qr/^[+-]?\d+$/; print YAPE::Regex::Explain->new($re)->explain();' The regular expression: (?-imsx:^[+-]?\d+$) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ^ the beginning of the string ---------------------------------------------------------------------- [+-]? any character of: '+', '-' (optional (matching the most amount possible)) ---------------------------------------------------------------------- \d+ digits (0-9) (1 or more times (matching the most amount possible)) ---------------------------------------------------------------------- $ before an optional \n, and the end of the string ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------
So, all in all the code checks if the content of $nth contains an integer with or without a prefix (+ or -); if it does not, then the removed code is executed.

Documentation: perlretut perlre

edit: hints about s/PERL/Perl/ and code tags removed, as choroba already mentioned it

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