本文共 1221 字，大约阅读时间需要 4 分钟。

记录：lua 判断table数据元素的数量：#table

local mysql = require "resty.mysql"local db, err = mysql:new()if not db then    ngx.say("failed to instantiate mysql: ", err)    returnenddb:set_timeout(1000) -- 1 seclocal ok, err, errno, sqlstate = db:connect{
       host = "",    port = 3306,    database = "",    user = "",    password = "",    max_packet_size = 1024 * 1024 }if not ok then    ngx.say("failed to connect: ", err, ": ", errno, " ", sqlstate)    returnendngx.say("connected to mysql.")-- 检查是否存在要生成的cors配置 configlocal select_sql = "select * from config where name='"..name.."' order by createtime asc"local corsconfig,err,errno,sqlstate = db:query(select_sql)if not corsconfig then		ngx.say("select rows error:",err,",errno:",errno,",sqlstate:",sqlstate)	breakend-- 判断corsconfig(table数据)元素的数量：#corsconfigif #corsconfig ~= 0 then    -- 循环此cdn服务下的所有CORS配置	for j,corsrow in ipairs(corsconfig) do	    -- 调用函数：生成单个cors配置文件	    createCorsConf(corsrow,name)	endend

但这种方法要慎用，使用过程中，遇到过这种bug:

local t = {
   "a", "a", "b", "b","c"} -- 重复的 a 会被过滤掉    LuaPrintTable(t,'table')    ngx.print(#t)   -- 打印结果：5        -- 过滤掉重复的元素    local n = uniqueTable(t)    LuaPrintTable(n,'table')    ngx.print(#n)   -- 打印结果：1    do return end

打印图示：

转载地址：https://blog.csdn.net/weixin_43652106/article/details/108596155 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！