Creating check digit from Hex code number

[Cep]

Hello,

 

I am trying to create a unique reference number with the following convention,

 

first char = region code

4 hex digits = decimal id number

final char = check digit

 

I have come up with a little function that I want to test out but I am having a problem type juggling the string into a hex number in order to perform the calculation.

 

Can anyone help me because I do not understand what is wrong?

 

<?php

$a = "FA45C6";

function breakdown($code) {

$region = substr($code, 0);

$check = substr($code, -1, 1);

$hex = "0x".substr($code, 1, -1);

$calc = (int)$hex % 10;

if ($calc==$check) {
	echo "We have a correct check digit";
} else {
	echo "Houston we have a problem - calc is {$calc}";
}

}

breakdown($a);
?>

[btherl]

For base conversion, it's best to use base_convert()

 

The reason is that "0x" is part of php's syntax, and is not considered when turning strings into integers.  You could use eval() to force it to interpret it as php syntax, but that's overkill.

[Cep]

Thanks btherl, I see what you mean.

[mainewoods]

hexdec()

http://us2.php.net/manual/en/function.hexdec.php

 

$dec = hexdec(substr($code, 1, -1));
$calc = $dec % 10;