function make_checkdigit in ISBN Field 6

1 call to make_checkdigit()

generate_ISN_corrections in ./isbn.inc

File

./isbn.inc, line 68

Code

function make_checkdigit($checksum) {
  $checkdigit = (11 - $checksum) % 11;
  return $checkdigit == 10 ? "X" : (string) $checkdigit;
}