# Four tabstop locations:
my @colpos = (8, 24, 36, 45);
while (....) {
    my @cols = split/\t/, get_next_string();
    # Print each column at its tabstop
    for (my $i=0; $i < @colpos; ++$i) {
        $pages[$page_number]->string($f2, 8,
                $colpos[$i], $y, $cols[$i]
        );
    }
}