[
   { start => 1, end => 1001, file => *FH1 },
   { start => 500, end => 2001, file => *FH2 }
]

##</code><code>##

for each line
   $position = getPosition()
   for $range in @ranges
      print $range->{FH} $line if (($position > $range->{start}) && ($position < $range->{end}))


##</code><code>##

SNP:for my $snp (@SNPs) {
        my @get_SNPs = split(/\t/, $snp);
        my $position = $get_SNPs[3];

        last SNP if ($position > $end); # stop reading, we're out of range !
                                        
        if (($position >= $start) && ($position <= $end)) {
            print OUT "@get_SNPs";
        }
    }

##</code><code>##

@array = split /\t/, $string;
my $v1 = $array[1];
my $v2 = $array[2];