大家帮忙看下这段代码哪有有关问题

<?php<br />$str='abcdefghijklmnopqrstuvwxyz'; <br />$count = 123456789;<br /><br />$str1 = $str[floor(floor(floor(floor(floor($count/26)/26)/26)/26)/26)];<br />$str2 = $str[floor(floor(floor(floor($count/26)/26)/26)/26)%26];<br />$str3 = $str[floor(floor(floor($count/26)/26)/26)%26];<br />$str4 = $str[floor(floor($count/26)/26)%26];<br />$str5 = $str[floor($count/26)%26];<br />$str6 = $str[$count%26];<br />echo $str1.'<br/>';<br />echo $str2.'<br/>';<br />echo $str3.'<br/>';<br />echo $str4.'<br/>';<br />echo $str5.'<br/>';<br />echo $str6.'<br/>';<br /><br />?>