PureBasic Forums - English

Code: Select all

Procedure.l LuhnCheck(pNumber.s)
  ; Luhn algorithm number checker - converted from JavaScript by Straker.
  ; 10-digit number checksum used for validating credit cards, etc.
  ; for more info see: http://en.wikipedia.org/wiki/Luhn_algorithm
  ;
  ; original JavaScript code by shaman @ www.planzero.org:
  ; http://planzero.org/code/bits/viewcode.php?src=luhn_check.js
  ; 
  ; 11-03-2008
  ; 
  ; Returns 1 if number is valid, otherwise 0
  ;
  Protected lRetVal.l, lNumLen.l, lTotal.l, lLoop.l
  Protected lDigit.l
  
  lRetVal.l = 0
  
  ; Strip any non-digits (useful For credit card numbers With spaces And hyphens)
  
  pNumber.s = ReplaceString ( pNumber.s, " ", "" )
  pNumber.s = ReplaceString ( pNumber.s, "-", "" )
  
  ; Set the string length
  lNumLen.l = Len ( pNumber.s )
  
  ; Loop through each digit And do the maths
  lTotal.l = 0
  
  For lLoop.l = 0 To (lNumLen.l - 1) Step 1
  
    lDigit.l = Val(Mid(pNumber.s,(lNumLen.l - lLoop.l),1))

    ; Multiply alternate digits by two
    If ((lLoop.l % 2) = 1)
    
      lDigit.l = (lDigit.l * 2)
    
      ; If the sum is two digits, add them together (in effect)
      If (lDigit.l > 9)
        lDigit.l = (lDigit.l - 9)
      EndIf

    EndIf

    ; Total up the digits
    lTotal.l = (lTotal.l + lDigit.l)

  Next lLoop.l
  
  ; If the total mod 10 equals 0, the number is valid
  If ((lTotal.l % 10) = 0)
    lRetVal.l = 1
  EndIf
  
  ProcedureReturn lRetVal.l
EndProcedure

Debug LuhnCheck("49927398716")

Debug LuhnCheck("808401912038795")

Code: Select all

Procedure.l Luhn_GetKey(number.s)
  
  Protected _parity, _digit, _sum, _i = Len(number)
  
  While _i 
    _digit = Val(Mid(number, _i, 1)) 
    _parity ~ _parity 
    _sum + _digit 
    If _parity 
      _sum + _digit 
      If _digit > 4
        _sum - 9 
      EndIf 
    EndIf 
    _i - 1
  Wend 
  
  _sum % 10 
  
  If _sum 
    ProcedureReturn 10 - _sum 
  EndIf 
  
EndProcedure

Procedure.l Luhn_IsValid(number.s)
  
  Protected _parity, _digit, _sum, _i = Len(number)
  
  While _i 
    _digit = Val(Mid(number, _i, 1)) 
    _sum + _digit 
    If _parity 
      _sum + _digit 
      If _digit + _digit > 9
        _sum - 9 
      EndIf 
    EndIf 
    _parity ~ _parity 
    _i - 1
  Wend
  
  If Not _sum % 10 
    ProcedureReturn #True
  EndIf 
  
EndProcedure

Debug Luhn_GetKey("4992739871") 
Debug Luhn_GetKey("80840191203879") 

Debug Luhn_IsValid("49927398716")
Debug Luhn_IsValid("808401912038795")