FileMaker Pro Custom Functions

/* The Luhn Mod-10 algorithm is used to validate ( check for input errors ) of many credit cards and Canadian Social Security numbers. This is a custom function implementation of the method used by Brian dunning in his Card Validator example. The functions LuhnDoubleEven and LuhnProduct are required for it to operate and must me defined prior to defining this function. */ Let( [ justNumbers = Filter( number ; "0123456789" ) ; // remove any non-numeric characters oddOrEvenLength = Mod(Length(justNumbers) ; 2) ; // odd length numbers return 1, even length numbers return 0 makeEven = Case(OddorEvenLength = 1; "0" ; "") & justNumbers ; // adds 0 to the front of any odd length number to make it even doubleEven = LuhnDoubleEven ( makeEven ) ; // doubles every 2nd number product = LuhnProduct ( doubleEven ) ; // Adds all the numbers together valid = Case( Mod( product ; 10 ) = 0 ; 1 ; 0 ) // The number is valid if it is exactly divisible by 10 ] ; // close let variable definition valid // return result ) // close let
 Then copy & paste into FileMaker Advanced's Edit Custom Function window.