$price = $rewardprice;

                $db->query("UPDATE {$tablepre}members SET extcredits$creditstrans=extcredits$creditstrans-$realprice WHERE uid='$discuz_uid'");
前面说过3表示悬赏帖子，那么当你发表成功了一个悬赏帖子后，就会相应在cdb_members表中减少相应的扩展积分，便是上面的代码的作用了。
elseif($special == 3 && $allowpostreward) {
                $db->query("INSERT INTO {$tablepre}rewardlog (tid, authorid, netamount, dateline) VALUES ('$tid', '$discuz_uid', $realprice, '$timestamp')");
        }
后续判断如果为悬赏帖子的话就往cdb_rewardlog(悬赏记录表)里写入一条记录。
        if($attachment) {
                $searcharray = $pregarray = $replacearray = array();
                foreach($attachments as $key => $attach) {
                        $db->query("INSERT INTO {$tablepre}attachments (tid, pid, dateline, readperm, price, filename, description, filetype, filesize, attachment, downloads, isimage, uid, thumb, remote)
                                VALUES ('$tid', '$pid', '$timestamp', '$attach[perm]', '$attach[price]', '$attach[name]', '$attach[description]', '$attach[type]', '$attach[size]', '$attach[attachment]', '0', '$attach[isimage]', '$attach[uid]', '$attach[thumb]', '$attach[remote]')");
                        $searcharray[] = '[local]'.$localid[$key].'[/local]';
                        $pregarray[] = '/\[localimg=(\d{1,3}),(\d{1,3})\]'.$localid[$key].'\[\/localimg\]/is';
                        $replacearray[] = '[attach]'.$db->insert_id().'[/attach]';
                }
                $message = str_replace($searcharray, $replacearray, preg_replace($pregarray, $replacearray, $message));
                $db->query("UPDATE {$tablepre}posts SET message='$message' WHERE pid='$pid'");
                updatecredits($discuz_uid, $postattachcredits, count($attachments));
        }
如果帖子中带有附件的话，就把附件插入cdb_attachments表，然后注意到$message这一个变量在这里用到了替换，这里的作用是图文混排。接下来往cdb_posts写一条记录，再用include/global.func.php定义到一个函数updatecredits来更新积分。
给Discuz的一个小建议：可以判断是不是postattachcredits为0，为0就可以不执行updatecredits这个函数，虽然在函数定义的时候也有判断，不过在这里判断似乎更好。
if($modnewthreads) {

                $db->query("UPDATE {$tablepre}forums SET todayposts=todayposts+1 WHERE fid='$fid'", 'UNBUFFERED');
                $allowuseblog && $isblog && $blog ? showmessage('post_newthread_mod_blog_succeed', "blog.php?uid=$discuz_uid") :
                        showmessage('post_newthread_mod_succeed', "forumdisplay.php?fid=$fid");

        } else {

                if($digest) {
                        foreach($digestcredits as $id => $addcredits) {
                                $postcredits[$id] = (isset($postcredits[$id]) ? $postcredits[$id] : 0) + $addcredits;
                        }
                }
                updatepostcredits('+', $discuz_uid, $postcredits);

                $lastpost = "$tid\t$subject\t$timestamp\t$author";
                $db->query("UPDATE {$tablepre}forums SET lastpost='$lastpost', threads=threads+1, posts=posts+1, todayposts=todayposts+1 WHERE fid='$fid'", 'UNBUFFERED');
                if($forum['type'] == 'sub') {
                        $db->query("UPDATE {$tablepre}forums SET lastpost='$lastpost' WHERE fid='$forum[fup]'", 'UNBUFFERED');
                }

                if($allowuseblog && $isblog && $blog) {
                        showmessage('post_newthread_blog_succeed', "blog.php?tid=$tid");
                } else {
                        showmessage('post_newthread_succeed', "viewthread.php?tid=$tid&extra=$extra");
                }

        }
这里是最后一段代码，作用是这样的：
首先看看是不是在发新帖的时候就被加为文集