Validate UPC - Create valid UPC

[dclamp]

This class i created will validate a supplied UPC code.

Class

<?php
class upcvalidator {
    
    function createCheckDigit($code) {
        if ($code) {
            for ($counter=0;$counter<=strlen($code)-1;$counter++) {
                $codearr[]=substr($code,$counter,1);
            }
            
            for ($counter=0;$counter<=count($codearr)-1;$counter++) {
                if ( $counter&1 ) {
                    $evensum = $evensum + $codearr[$counter];
                } else {
                    $oddsum = $oddsum + $codearr[$counter];
                }
            }
            
            $oddsum = $oddsum *3;
            $oddeven = $oddsum + $evensum;
            
            for ($number=0;$number<=9;$number++) {
                if (($oddeven+$number)%10==0) {
                    $checksum = $number;
                }
            }
            
            return $checksum;
        } else {
            return false;
        }
    }
    
    function validateUPC($upc) {
        if ($upc!="") {
            $checkdigit = substr($upc, -1);
            $code = substr($upc, 0, -1);
            
            $checksum = $this->createCheckDigit($code);
            if ($checkdigit == $checksum) {
                return true;
            } else {
                return false;
            }
        } else {
            return false;
        }
    }
    
    function createUPC($code) {
        if ($code) {
            $checkdigit = $this->createCheckDigit($code);
            $upc = $code . $checkdigit;
            
            return $upc;
        } else {
            return false;
        }
    }
}
?>

Functions

createCheckDigit($code) - When supplied with an 11 digit code, will return the check digit. No practical use, used for the class.

createUPC($code) - When supplied with an 11 digit code, will return with the valid check digit amended to the code.

validateUPC($upc) - When supplied with the 12 digit UPC, will validate the UPC code.

Example

Create Class

require_once ("$class.upcvalidator.php");
$upcvalidate = new upcvalidator; 

validateUPC()

//valid upc
$upc = 639382000393;
$validate = $upcvalidate->validateUPC($upc); //returns true

//invalid upc
$upc = 123456789123;
$validate = $upcvalidate->validateUPC($upc); //returns false 

createUPC()

$code = 12345678900; // 11 digit code
$upc = $upcvalidate->createUPC($code);
echo $upc; //returns 123456789005
//Notice the 5. 5 is the valid check digit.