Credit Card Validation Question

[Sparky Arbuckle]

The code below will pass a credit card as being valid if it contains
dashes, spaces, and also alphanumerics. How can I check for only dashes
and spaces and return invalid when the user inputs alphanumerics?
Thanks.


Sub ValidateCCNumber( s As Object, e As ServerValidateEventArgs )
Dim intCounter As Integer
Dim strCCNumber As String
Dim blnIsEven As Boolean = False
Dim strDigits As String = ""
Dim intCheckSum As Integer = 0

'Strip away everything except numerals
FOR intCounter = 1 To Len( e.Value )
IF IsNumeric( MID( e.Value, intCounter, 1 ) ) THEN
strCCNumber = strCCNumber & MID( e.Value, intCounter, 1 )
END IF
NEXT

'IF nothing left, then fail
IF Len( strCCNumber ) = 0 THEN
e.IsValid = False
ELSE

'Double every other digit
FOR intCounter = Len( strCCNumber ) To 1 Step -1
IF blnIsEven THEN
strDigits = strDigits & cINT( MID( strCCNumber, intCounter, 1 )
) * 2
ELSE
strDigits = strDigits & cINT( MID( strCCNumber, intCounter, 1 )
)
END IF
blnIsEven = ( NOT blnIsEven )
NEXT

'Calculate CheckSum
FOR intCounter = 1 To Len( strDigits )
intCheckSum = intCheckSum + cINT( MID( strDigits, intCounter, 1
) )
NEXT

'Assign results
e.IsValid = (( intCheckSum Mod 10 ) = 0 )

END IF
END Sub

 

[Brock Allen]

Look into using regular expressions:

http://www.codeproject.com/aspnet/creditcardvalidator.asp

http://www.codeproject.com/aspnet/CreditCardValidator2.asp

http://www.evolt.org/article/Validating_a_Credit_Card_Number_with_JavaScript/17/24700/

 

[Kevin Spencer]

Search Google for a Regular Expression that validates a Credit Card. There
are plenty.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
What You Seek Is What You Get.