Match character position in perl

my $line = "foo 123 bar";
if ($line =~ m{(\d+)}g) {
   my $pos = pos($line) - length $1;
   print "$pos\n\n";   
}

my $line = "foo 123 bar";
if ($line =~ m{(\d+)}g) {
    my $pos = length $`;
    print "$pos\n";
}