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Re: Limiting number of regex matches

by Marshall (Abbot)
on Sep 25, 2012 at 20:42 UTC ( #995630=note: print w/replies, xml ) Need Help??


in reply to Limiting number of regex matches

The easiest way is not to limit the number of regex matches, but to trim the results with a list slice.
Let match global do its thing and then return the first 3 matches.
#!/usr/bin/perl -w use strict; my $str='dog dog horse dog cow dog pig dog'; my @dogs = ($str =~ m/dog/g)[0..2]; print "number of dogs = ".@dogs,"\n"; # the . concatenation puts @dogs in a scalar context # same as print scalar(@dogs) print "@dogs\n"; ################## # so what happens if there aren't 3 dogs? # one way is to use map to filter the undef's out # To return a "nothing at all" from map, use () # undef is a value and that won't work... # # This returns a maximum of 3 dogs if there are that # many or more dogs, otherwise it returns less. # my $second_pack = "dog horse cow"; @dogs = map{$_ or ()}($second_pack =~ /dog/g)[0..2]; print "\nsecond pack = ".@dogs, " dogs\n"; print "@dogs"; __END__ number of dogs = 3 dog dog dog second pack = 1 dogs dog

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[Eily]: I just wrote a oneliner to solve a (non perl) colleague's problem, and it worked on the first try
[Eily]: and he wasn't impressed
1nickt adds gingersnaps to the platter on the sideboard.
[Eily]: sure it was a pretty standard one liner (of the $h{$1} = $2 if /regex/; END { pp \%h; } variety), but he's not supposed to know that!
[Eily]: what's the point of writing perl if people aren't impressed :P
[sierpinski]: Haha
[Discipulus]: i'm with you!
[Discipulus]: with eskimo greeting is a little bit impressing, anyway

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