>Alain has very nicely merged our two functions into one which uses
>the Luhn algorithm to check the validity of account number and return
>the card type from the account number.
>
Wow, there's some complex-looking stuff in there. Must have been translated from c++ or something. Would you believe that this...

>FOR i = 0 TO L - 1
>cc( i) = val&( CHR$( ccNum[i + 1]  ) )
>LONG IF( i MOD 2 != 0 AND L MOD 2 != 0) ¬
>OR( i MOD 2 = 0 AND L MOD 2 = 0 )
>cc( i ) = cc( i ) < < 1
>LONG IF cc( i ) > = 10
>temp = STR$( cc( i ) )
>cc( i )  = val&( CHR$( temp[2]  ) ) ¬
>  + val&( CHR$( temp[3] )  )
>END IF
>END IF
>NEXT i
>
>FOR i = 0 TO L - 1
>value + = cc( i )
>NEXT i

...all boils down to this?...

>FOR i = 1 TO L
>temp = ccNum[i] and 15
>LONG IF L - i and 1
>temp += temp
>IF temp > 9 then temp -= 9
>END IF
>value += temp
>NEXT i

Here's a purtified version of the whole thing.

 0"0
 =J= a  y
  "

'----------- BEGIN FB^3 CODE ------------

'~FN CCVERIFY$ (Credit card verifier)

// Contributed 10-30-01
// Alain Pastor and Ken Shmidheiser

LOCAL MODE
LOCAL FN CCVerify$(  ccNum AS STR63  )
DIM i, L, value, twoChars, fourChars, temp
DIM ccType AS STR63

ccType = "Unknown Credit Card Type"
value  =  0
L      =  ccNum[0]
temp   = 0
FOR i  =  1 TO L
select ccNum[i]
case _" "  : temp ++
case <  _"0", >  _"9" : EXIT fn
case else : ccNum[i-temp] = ccNum[i]
end select
NEXT i

L        -= temp
ccNum[0]  = L
twoChars  = {@ccNum[1]}
fourchars = [@ccNum[1]]
SELECT L

CASE 16
SELECT ccNum[1]
CASE  _"5"
IF ccNum[2] > = _"1" AND ccNum[2] < = _"5"¬
    THEN ccType   = "MasterCard"
CASE  _"4" : ccType = "VISA"
CASE  _"3" : ccType = "JCB"
CASE  _"6"
if fourchars = _"6011" then ccType = "Discover"
END SELECT

CASE 15
SELECT
CASE twoChars = _"34", twoChars = _"37"
ccType = "AMEX"
CASE fourchars = _"2014", fourchars = _"2149"
ccType = "enRoute"
CASE fourchars = _"2131", fourchars = _"1800"
ccType = "JCB"
END SELECT

CASE 14
SELECT twoChars
CASE _"30"
LONG IF ccNum[3] > = _"1" AND ccNum[3] < = _"5"
ccType = "Diners Club/Carte Blanche"
END IF
CASE _"36", _"38"
ccType = "Diners Club/Carte Blanche"
END SELECT

CASE 13
IF ccNum[1] = _"4" THEN ccType = "VISA"

END SELECT

LONG IF ccType != "Unknown Credit Card Type"

FOR i = 1 TO L
temp = ccNum[i] and 15
LONG IF L - i and 1
temp += temp
IF temp > 9 then temp -= 9
END IF
value += temp
NEXT i

LONG IF value mod 10 = 0
ccType = "Valid " + ccType + " Credit Card Number"
XELSE
ccType = "Invalid Credit Card Number"
END IF

END IF

END FN = ccType

DIM cc AS STR255
cc = "4417 1258 2618 8868"
PRINT FN CCVerify$( cc )

DO
UNTIL FN BUTTON

'-------------- END FB^3 CODE -------------