public function filter($str)
    {
        $str = preg_replace("|[\D+]|", "", $str);

        if (strlen($str) == 11 && in_array(substr($str, 0, 1), array("7", "8"))) {
            $str = substr($str, 1);
        }

        $len2 = strlen($str);

        return $len2 == 10 ? $str : "";
    }
public function filter($str)
    {
        $str = preg_replace("|[\D+]|", "", $str);

        if (strlen($str) == 11 && in_array(substr($str, 0, 1), array("7", "8"))) {
            $str = substr($str, 1);
        }

        $len2 = strlen($str);

        return $len2 == 10 ? $str : "";
    }
public function filter ( $ str ) { $ str = preg_replace ( "|[\D+]|" , "" , $ str ) ; if ( strlen ( $ str ) == 11 && in_array ( substr ( $ str , 0 , 1 ) , array ( "7" , "8" ) ) ) { $ str = substr ( $ str , 1 ) ; } $ len2 = strlen ( $ str ) ; return $ len2 == 10 ? $ str : "" ; }
Returns only digits from source string. If string is
11 chars length and first char is 7 then that char is stripped
@param  string $str Source string
@return string Filtered string
Returns only digits from source string . If string is 11 chars length and first char is 7 then that char is stripped