my $data_in="ISBN 90-70002-34-5";
   $data_in=~ s/^ISBN//;
   $data_in=~ s/ /-/g;
   $data_in=~ s/-//g;
my @isbn=split('', $data_in);
my $count=scalar @isbn;
unless (($count eq 10) && (!($count=~ m/[a-z]/i))){
   warn "not enough digits in ISBN: $count instead of 10\n";
}
##</code><code>##

# data from the database you are checking against
my $data_in="90 70002 34 5";
# inputed data
my $check_data="ISBN 90-70002-34-5";
   $check_data=~ s/^ISBN//;
   $check_data=~ s/-/ /g;
   $check_data=~ s/^ //;
unless (($data_in eq $check_data) && (!($count=~ m/[a-z]/i))){{
   die "failure: data in does not match db record\n";
}