my @True;
for my $Element (@Array){
  if ($Element){
    push @True, $Element;
  }
}

##</code><code>##

my @True = grep {$_} @Array;

##</code><code>##

#(For every fourth element in @List)
grep {not ++$i % 4} @List;

#(To skip every fifth element)
grep {++$i % 5} (1..50)