Swedish "personnummer"
Think of it like a social security number or something, everyone in sweden gets one. This is a easy calculation, the number itself looks something like
Think of it like a social security number or something, everyone in sweden gets one. This is a easy calculation, the number itself looks something like
780101-8917
The different parts of the number have different meanings. The first six digits tells us that this person was born January 1, 1978. This is followed by a "-" where the next two digits is a code for the region this person was born in. The second last digit represents the gender on this person where and even number means it's a female, and odd number for a male.
The last number is a "control number" to validate the combination of digits. In the above example this is a "7", I'll now show how to calculate this, instructions quoted in-line.
The last number is a "control number" to validate the combination of digits. In the above example this is a "7", I'll now show how to calculate this, instructions quoted in-line.
780101891 (all numbers except control one)
*212121212 (always use this digit string)
=1+4+8+1+0+1+1+6+9+2 > 33 (in result line split 10+ sums into single digits, then add)
10 - 3 = 7 (take 10 minus the last digit in above sum)
7 (this is th control digit for above example)
*212121212 (always use this digit string)
=1+4+8+1+0+1+1+6+9+2 > 33 (in result line split 10+ sums into single digits, then add)
10 - 3 = 7 (take 10 minus the last digit in above sum)
7 (this is th control digit for above example)
So why would this be a good thing to know? Well, if you every try to "make up an identity", registering at a swedish site or something like it - this place usually has an automated check of the control number. It's rather rare with a control against some "real" register, this simple check is usually it. To make it real simple, I'll add a calculator for you here.
Below is the code this form executes to calculate this. I "sorta" tried to keep it clean and fairly optimised, if I succeeded is up to you to tell I suppose. In the end it comes down to discrete mathematics when optimising algorithms ... and really, math wasnt ever my thing. Cheers.
<?
if(isset($_POST['strPnr'])){
$pnr = $_POST['strPnr'];
if(strlen($pnr) == 9 && is_numeric($pnr)){
// All ok, do the trick
$check = array(2,1,2,1,2,1,2,1,2);
$resarray = array(0);
for($i=0;$i<9;$i++){
if(($pnr[$i] * $check[$i]) > 9){
$resarray[] = substr($pnr[$i] * $check[$i], 0, 1);
$resarray[] = substr($pnr[$i] * $check[$i], 1, 1);
}else{
$resarray[] = $pnr[$i] * $check[$i];
}
}
if(array_sum($resarray) > 9){
$final = 10 - substr(array_sum($resarray), 1, 1);
}else{
$final = 10 - array_sum($resarray);
}
echo "Control number is: " . substr($final, (strlen($final)-1), 1);
}else{
echo "Incorrect numbers of digits provided or illegal characters used";
}
}
?>