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'**************************************
' Name: Credit Card Checksum Checker
' Description:Checks to see if a Credit
' Card Number is valid by performing the L
' UHN-10 check on it.
' By: John Anderson
'
' Inputs:CCNum as String
'
' Returns:True if Valid, False if Invali
' d
'
' Side Effects:May cause skin irritation
'
'
'This code is copyrighted and has' limited warranties.Please see http://w
' ww.Planet-Source-Code.com/vb/scripts/Sho
' wCode.asp?txtCodeId=902&lngWId;=1'for details.'**************************************
Public Function IsValidCCNum(CCNum As String) As Boolean
Dim i As Integer
Dim total As Integer
Dim TempMultiplier As String
For i = Len(CCNum) To 2 Step -2
total = total + CInt(Mid$(CCNum, i, 1))
TempMultiplier = CStr((Mid$(CCNum, i - 1, 1)) * 2)
total = total + CInt(Left$(TempMultiplier, 1))
If Len(TempMultiplier) > 1 Then total = total + CInt(Right$(TempMultiplier, 1))
Next
If Len(CCNum) Mod 2 = 1 Then total = total + CInt(Left$(CCNum, 1))
If total Mod 10 = 0 Then
IsValidCCNum = True
Else
IsValidCCNum = False
End If
End Function
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Other 1 submission(s) by this author
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| Other User Comments |
6/29/1999 8:26:00 AM:fengbald
Nice routine will use it at work.
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7/19/1999 3:08:00 PM:odeadendo
good idea
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8/19/1999 11:00:00 AM:blah
How do we use this?? I mean... how do I
tell it what the CCNum is.. and when to
check it?
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9/5/1999 9:48:00 AM:slackker
John would it be possible to know what
the interface should be like or have on
it to use this code? Thanks slackker
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9/22/1999 10:05:00 AM:Faisal
Thanx for the code. I was just
wondering, won't it be dangerous to use
this code to create valid credit card
numbers? If so then you should prevent
it somehow. Thanx again.
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10/19/1999 9:55:00 AM:Kevin
Can you just paste this into a web page
as VBScript?
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10/27/1999 1:19:00 PM:JP
wow... didn't knew CCChecksum was that
easy ;)
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11/21/1999 3:26:00 PM:dynasty
any cc generater could outsmart this
program.....no good... -=)
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11/26/1999 8:21:00 PM:UM
not nessisarily
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12/28/1999 8:38:55 PM:John Anderson
blah - CCNum should be a string
containing the Credit Card number
without spaces/dashes/etc. The routine
returns True if Valid, False if
not.
slackker - This was developed
for use in an e-commerce solution. The
best way to use this is to do a quick
check for typos before submitting the
card number to your
processor.
Faisal - This checksum
method is widely known. The only 100%
secure way to verify a valid card
number is through a credit card
processor (i.e. Cybercash)
dynasty -
You're right. But the odds of your CC
Generator picking the number of a valid
card are less than the odds of you
winning the lottery. =)
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