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Re: regular expression and grep function questions

by kcott (Chancellor)
on Mar 02, 2013 at 00:49 UTC ( #1021369=note: print w/replies, xml ) Need Help??

in reply to regular expression and grep function questions

G'day dicty,

\z is used in regular expressions as an anchor to match the end of a string (which could be multi-line). It differs from $ which matches the end of a line; and, it is subtly different from \Z (uppercase Z) which matches the end of the string but optionally before a newline if one exists.

The following code demonstrates each of these differences:

$ perl -Mstrict -Mwarnings -E ' my $string = "abc\ndef\n"; $string =~ /(.*?)$/ms; say q{[$]}, $1, q{[$]}; $string =~ /(.*?)\z/ms; say q{[z]}, $1, q{[z]}; $string =~ /(.*?)\Z/ms; say q{[Z]}, $1, q{[Z]}; ' [$]abc[$] [z]abc def [z] [Z]abc def[Z]

Under perlre - Regular Expressions, $ is described in the Metacharacters section and \z and \Z are described in the Assertions section.

I see hippo has answered your second question.

-- Ken

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