PERL: Sum of Number String

sum_of_number_string.pl

#!/usr/bin/perl -w
# string of number
# sum number larger than 0
# report start and end site

my $line = shift;
my @numbers = (split //,$line);

my $tag = 0;
my $sum = 0;

my $start;
my $end;
for (my $i = 0; $i <= @numbers-1;$i++ ) {
	if ($numbers[$i] > 0 ){
		$sum = $sum +$numbers[$i];
		if ($tag ==0){
			$tag =1;
			$start = $i;
			$end = $i;

		}
		elsif ($tag ==1){
			$end ++;
		}
		if ( $i == @numbers -1){
			print "$start\t$end\t$sum\n";
		}
	}
	else {
		if ($tag == 1){
			print "$start\t$end\t$sum\n";
			$sum =0;
			$tag = 0;
		}
		elsif ($tag ==0){
			($start, $end, $sum) = (0,0,0);
		}
	}
}