Format and valid SSN number

gistfile1.txt

<?php
    /*
    PHP Library - Social Security Number-related functions
    
    Copyright (c) 2009, reusablecode.blogspot.com; some rights reserved.
    
    This work is licensed under the Creative Commons Attribution License. To view
    a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ or
    send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California
    94305, USA.
    */
 
    // Format a Social Security Number.
    function formatSSN($ssn)
    {
        if (eregi("^(\d{3})\-?(\d{2})\-?(\d{4})$", $ssn))
        {
            return eregi_replace("^(\d{3})\-?(\d{2})\-?(\d{4})$", "$1-$2-$3", $ssn);
        }
        else
        {
            die("Input cannot be formatted as a social security number.");
        }
    }
 
    // Validate a Social Security Number.
    function isValidSSN($ssn)
    {
        $result = eregi("^\d{3}\-?\d{2}\-?\d{4}$", $ssn) ? true : false;
 
        /*
        None of the digit groups can be all zeros.
        Area number 666 is unassigned.
        Numbers from 987-65-4320 to 987-65-4329 are reserved for use in advertisements.
        Many SSNs have been invalidated by use in advertising.
        */
        if (eregi("^((000|666)\-?\d{2}\-?\d{4}|\d{3}\-?00\-?\d{4}|\d{3}\-?\d{2}\-?0000|987\-?65\-?432\d{1}|042\-?10\-?3580|062\-?36\-?0749|078\-?05\-?1120|095\-?07\-?3645|128\-?03\-?6045|135\-?01\-?6629|141\-?18\-?6941|165\-?(16|18|20|22|24)\-?7999|189\-?09\-?2294|212\-?09\-?(7694|9999|219\-?09\-?9999|306\-?30\-?2348|308\-?12\-?5070|468\-?28\-?8779|549\-?24\-?1889)$", $ssn)
        {
            $result = false;
        }
 
        // Numbers above 772 are currently unassigned.
        if (substr($ssn, 0, 3) > 772)
        {
            $result = false;
        }
 
        return $result;
    }
 
?>