Algorithms

checkdigit modulo 10

Type:	code fragment
Added by:	ulflun
Entered:	02/11/2001
Last modified:	01/12/2010
Rating:	(5 votes)
Views:	6436

Calculates the checkdigit, cdv 10, for either a integer or string value. Cdv10 are often used in account-numbers etc.

<?php

                                function cdv10($str)

                                {

                                    if (is_string($str))

                                    {

                                        for ($i=0;$i<strlen($str); $i++)

                                        {

                                            $out = $out . Ord(substr($str,$i,1));

                                        }

                                    }

                                    else

                                        $out=$str;

                            

                                    // is the length odd or even

                                    if ((int)(strlen($out)/2)    == (int)((strlen($out)/2)+0.9))

                                        $m=0;

                                    else

                                        $m=1;

                            

                                    // sum the values for each digit, take care of values > 9

                                    for ($i=0;$i<strlen($out); $i++)

                                    {

                                        $m=($m==1)?2:1;

                                        $v=$m*substr($out, $i, 1);

                                        if ($v>9)

                                            $v=(substr($v, 0, 1)+substr($v, 1, 1));

                                        $sum = $sum + $v;

                                    }

                            

                                    // what is the check digit??

                                    $cd=(round($sum/10+0.49)*10) - $sum;

                            

                                        return $cd;

                                }
?>

Usage Example

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