function canonical_ISBN in ISBN Field 6

1 call to canonical_ISBN()

canonical_ISN in ./isbn.inc

File

./isbn.inc, line 350

Code

function canonical_ISBN($isbn_proto) {
  $isbn_proto = ISN_clean($isbn_proto);
  global $country_group_map;
  $cg = country_group_code($isbn_proto);
  $cglen = strlen($cg);
  $pubandbook = substr($isbn_proto, $cglen, 9 - $cglen);
  $checkdigit = $isbn_proto[9];
  if (is_array($country_group_map[$cg])) {
    $publen = prefix_length_from_map($pubandbook, $country_group_map[$cg][0]);
    if ($cglen + $publen == 9) {
      return "{$cg}-{$pubandbook}-{$checkdigit}";
    }
    else {
      $pubcode = substr($pubandbook, 0, $publen);
      $bookno = substr($pubandbook, $publen);
      return "{$cg}-{$pubcode}-{$bookno}-{$checkdigit}";
    }
  }
  else {
    return "{$cg}-{$pubandbook}-{$checkdigit}";
  }
}