By "NULL," do you mean only undefined items or also the empty ones?

If you want to exclude only the items that are not defined, then use

my @clean = grep { defined } @data;
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If you want to skip the empty items, then use

my @clean = grep { $_ ne '' } @data;
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However, the above code will break on undefined items. If you want to combine both approaches, then the "right" approach is:

#!/usr/bin/perl -w
use strict;

my @data= (1, 2, 3, 'a', undef, 4, '', 5, 'b');

my @clean = grep { defined && $_ ne ''  } @data;

print join ",", @clean;
print "\n";
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output:

1,2,3,a,4,5,b

HTH

cchampion