use strict;
"blah" =~ /(a)/;       # now we've set $1 at the global scope

my $i = "mmmm9";
my $a = match_rtn( $i );
print $a, "\n";

$i = "mmm";
$a = match_rtn( $i );
print $a, "\n";        # ook! this isn't undefined!

sub match_rtn {
    my $str = shift;
    $str =~ m/(\d+)/;
    return $1;   
}