Comments on: PHP Luhn modulus implementation

By: Duam

Duam — Wed, 24 Mar 2010 16:42:40 +0000

>>>>>>>>>>>> http://www.duam.com.mx <<<<<<<<<<<<<<<

By: Trink

Trink — Tue, 24 Nov 2009 00:29:49 +0000

Wow my bad, I just copied and pasted my code and didn’t pay attention to the greater than and less than signs. It should actually look like this:
function luhn_validate($input, $mod5 = false){
$total = 0;
settype($input,’string’);
$length = strlen((string)$input);
$parity = $length % 2;
for($i = 0;$i < $length;$i++) $total += ($i % 2 === $parity ? (($x = (int)$input[$i] * 2) > 9 ? $x – 9 : $x) : (int)$input[$i]);
return (($total % ((boolean)$mod5 ? 5 : 10)) == 0);
}

By: Trink

Trink — Tue, 24 Nov 2009 00:26:50 +0000

function luhn_validate($input, $mod5 = false){
$total = 0;
settype($input,’string’);
$length = strlen((string)$input);
$parity = $length % 2;
for($i = 0;$i 9 ? $x – 9 : $x) : (int)$input[$i]);
return (($total % ((boolean)$mod5 ? 5 : 10)) == 0);
}

By: chanthu

chanthu — Fri, 18 Sep 2009 07:48:05 +0000

Nice one…..

By: chanthu

chanthu — Fri, 18 Sep 2009 07:47:37 +0000

thanks for the algorithm….

By: Alix Axel

Alix Axel — Sun, 13 Sep 2009 23:57:24 +0000

Thanks for the reference, here is a function to generate a Luhn checksum:

function Luhn($number, $iterations = 1)
{
while ($iterations– >= 1)
{
$stack = 0;
$number = str_split(strrev($number), 1);

foreach ($number as $key => $value)
{
if ($key % 2 == 0)
{
$value = array_sum(str_split($value * 2, 1));
}

$stack += $value;
}

$stack %= 10;

if ($stack != 0)
{
$stack -= 10;
}

$number = implode(”, array_reverse($number)) . abs($stack);
}

return $number;
}

A validation that uses this function can also be easily coded.