Luhn10.isValid ( _number ; _requiredLength )

Validates Credit Card numbers, SIREN, Canadian Social Security numbers…

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Fabrice Nordmann - Show more from this author
1-more-thing
https://www.1-more-thing.com

Sample input:

Luhn10.isValid ( "4012 8888 8888 1881" /*(Visa)*/ ; 16 )

Sample output:

Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

/*
	Luhn10.isValid ( _number ; _requiredLength )
	by Fabrice Nordmann, 1-more-thing
	Jan 2023

	parameters:
		_number: the number to check
		_requiredLength: optional: allows to check the length of the number (digits only).
		For example pass 16 for a Visa card, or 9 for a SIREN ID.

	result: Boolean (True for Valid)

	input examples (valid numbers)
		- Credit card numbers:
			- 5555 5555 5555 4444 (MasterCard)
			- 5185 5408 1000 0019 (MasterCard)
			- 4012 8888 8888 1881 (Visa)
			- 4111 1111 1111 1111 (Visa)
			- 3714 496353 98431 (AMEX)
			- 3782 822463 10005 (AMEX)
		- SIREN Company ID (France)
			- 813730132
			- 892185877
			- 794430686
		- Canadian social security
		- many more…
*/

While (
	[
		_number = Filter ( _number ; 1234567890 ) ;
		_lengthError = _requiredLength and _requiredLength <> Length ( _number ) ;
		i = "" ;
		d = "" ;
		r = "" ;
		c = Case ( _lengthError ; 0 ; length ( _number ))
	];
		i < c ;
	[
		i = i + 1 ;
		d = Middle ( _number ; c + 1 - i ; 1 ) ;
		v = d * Case ( Mod ( i ; 2 ) ; 1 ; 2 ) ;
		v = Case ( v > 10 ; Left ( v ; 1 ) + Right ( v ; 1 ) ; v ) ;
		r = r + v
	];
	Right ( r ; 1 ) = 0
)

/*
Luhn10.isValid ( _number ; _requiredLength )
by Fabrice Nordmann, 1-more-thing
Jan 2023

parameters:
_number: the number to check
_requiredLength: optional: allows to check the length of the number (digits only).
For example pass 16 for a Credit card number, or 9 for a SIREN ID.

result: Boolean (True for Valid)

input examples (valid numbers)
- Credit card numbers:
- 5555 5555 5555 4444 (MasterCard)
- 5185 5408 1000 0019 (MasterCard)
- 4012 8888 8888 1881 (Visa)
- 4111 1111 1111 1111 (Visa)
- 3714 496353 98431 (AMEX)
- 3782 822463 10005 (AMEX)
- SIREN Company ID (France)
- 813730132
- 892185877
- 794430686
- Canadian social security
- many more…
*/

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Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

Luhn10.isValid ( _number ; _requiredLength )

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