帮忙看一个函数,该怎么处理

function listlist(&$num) 
{
    //if(1==$page) $num_last=1;
    //else $num_last=$num-100+1;
    $file_name="data";
    
    $real_num=0;
    for(;$real_num<=100;$num--)
    {
        $file_temp=$file_name.$num.".txt";
        if(FALSE==file_exists($file_temp)) continue;
        else
        {
            $real_num++;
            $message=file($file_temp);
            $len=count($message);

            echo '';
            echo'';
            echo'';
            echo'";
            echo"";
            //echo"
";
            echo'';
            echo'";
            echo"";
            echo'
';
            //$message=fgets($fd_temp);
            echo $message[0];
            echo"\n";

            echo $i;

            echo'
';
            echo"删除留言";
            echo"
';

            for($i=1;$i<$len;$i++)
            {
            echo $message[$i];

            }
            echo"
';
        }
    }
    $num--;
}