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Re: Error in my Regular expression pattern

by Marshall (Abbot)
on Mar 18, 2012 at 16:54 UTC ( #960298=note: print w/replies, xml ) Need Help??

in reply to Error in my Regular expression pattern

To expand upon the AnonMonk's suggestion.
Maybe this helps to show what is going on?
#!/usr/bin/perl -w use strict; my $string = "Twinkle twinkle little star"; my @matches = $string =~ m/twinkle/ig; print "Matches are: @matches\n"; # Matches are: Twinkle twinkle print "Number of matches: ",scalar @matches,"\n"; print "\n"; # this is the same without creating @matches # the () is a list and $n here is number of things # in that list # # Without the intervening ()=, to force list context, # you just get the "truthfulness" (0,1) of the match # with this, you get the number of things in the list # without having to create a named array (@matches) my $n = () = $string =~ m/twinkle/ig; print "Number of occurences = $n\n"; __END__ Matches are: Twinkle twinkle Number of matches: 2 Number of occurences = 2
PS: I try to avoid assigning to $_ when possible (and sometimes this is necessary), but I figure that $_ "belongs to Perl". The expression:
foreach ($string) { s/^\s*//; #delete leading spaces s/\s*$//; #delete trailing spaces }
is seen often and has this effect of assigning $string to $_. $string gets modified due to "aliasing".

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