CCTYPE(SEXP) (STRING)

 Function
  Determine the issuer of a credit card based on the credit card number.

 Syntax
  CCTYPE(ccnum)

   ccnum = A string expression with the credit card number that is to
           be checked.

 Return Type & Value
  STRING
  Returns a string with the name of the card.

 Remarks
  PPL can be used to perform some simple credit card validation.  This
  function returns the issuer of a credit card based on the credit card
  number.

  For example, a valid credit card number that starts with a "4" is a Visa
  card, so the string "VISA" will be returned.  If a credit card is invalid
  (VALCC() = FALSE) or not recognized, then "UNKNOWN" will be returned.
  Other valid credit card with known types will return the appropriate
  string.

  The following card types are recognized by PPL:
  "DISCOVER", "CARTE BLANCHE", "DINERS CLUB", "OPTIMA", "AMERICAN EXPRESS",
  "VISA", and "MASTERCARD".

 Examples
  STRING s
  INPUT "Credit card number",s
  IF (VALCC(s)) PRINTLN LEFT(CCTYPE(s),20)," - ",FMTCC(s)