【高级技巧】Lua哨兵语义：沙巴克守城报名0次与没报名的区分

local n = getplayvar(actor, "SBK_SIGN") or 0
if n == 0 then
    giveitem(actor, "金元", 5, 0, "守城补贴")  -- 从未报名也发
end

local n = getplayvar(actor, "SBK_SIGN")
if n == nil then
    sendmsg(actor, 1, "尚无沙巴克报名记录")
else
    n = tonumber(n)
    if n == 0 then
        sendmsg(actor, 1, "报名 0 次，本轮抓紧")
    else
        giveitem(actor, "金元", n, 0, "守城奖励")
    end
end