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Credit Card Checksum Checker
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Email
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| Submitted on: |
5/27/1998 |
| By: |
John Anderson
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| Level: |
Not Given |
| User Rating: |
By 3 Users |
| Compatibility: |
VB 3.0, VB 4.0 (16-bit), VB 4.0 (32-bit), VB 5.0, VB 6.0 |
| Views: |
37966 |
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Checks to see if a Credit Card Number is valid by performing the LUHN-10 check on it.
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code:
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By using this code, you agree to the following terms...
- You may use
this code in your own programs (and may compile it into a program and distribute it in compiled format for languages that allow it) freely and with no charge.
- You MAY NOT redistribute this code (for example to a web site) without written permission from the original author. Failure to do so is a violation of copyright laws.
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- You will abide by any additional copyright restrictions which the author may have placed in the code or code's description.
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'**************************************
' Name: Credit Card Checksum Checker
' Description:Checks to see if a Credit Card Number is valid by performing the LUHN-10 check on it.
' By: John Anderson
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' Inputs:CCNum as String
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' Returns:True if Valid, False if Invalid
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' Side Effects:May cause skin irritation
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'This code is copyrighted and has' limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.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
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 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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