Lua随手记

官网：http://www.lua.org/

手册：http://www.lua.org/manual/5.2/manual.html

社区：http://lua-users.org/

论坛：http://www.luaer.cn/

在线中文手册：http://manual.luaer.cn

1.Lua中...可表示可选参数，但是跟arg的区别有些大啊！而且如果在一个函数内同时使用...和arg的话，...有效、arg会变成nil（2014.7.17 看skynet代码时发现，arg在5.1跟5.2貌似有些区别，最好是只在获取命令行参数用arg，获取函数可变参数用...，这样可规避问题。）

function func1(...)print(type(arg),'->',arg)for k,v in pairs(arg) doprint(k,v)endendfunction func2(...)print(type(...),'->',...)for k,v in pairs({...}) doprint(k,v)endendfunc1(1,2,3,4,5)print(string.rep("-", 20))func2(1,2,3,4,5)OUTPUT:table   ->      table: 00A6B2181       12       23       34       45       5n       5--------------------number  ->      1       2       3       4       51       12       23       34       45       5

[root@test-22 lua-study]# cat var.lua local function f(...)    if not ... then print('empty'); return end    local t = {}    for i = 1, select('#',...) do        print('i', i, select(i,...))        t[i] = select(i,...)    end    for k,v in pairs(t) do print(k,v) endendf('a', 'b', 'c')f()local function f2(a,...)    print('f2 called', a, ...)endf2('a', 1, 2, 3)f2('a', table.unpack({1,2,3})) --unpack的结果全部传入f2('a', false or table.unpack({1,2,3})) --只取upack的第一个结果[root@test-22 lua-study]# lua var.lua i       1       a       b       ci       2       b       ci       3       c1       a2       b3       cemptyf2 called       a       1       2       3f2 called       a       1       2       3f2 called       a       1

2.setmetatable会返回被操纵的table

oritable = {}local a = setmetatable(oritable, {__mode="k"})print("oritable=", oritable)print("setmetable(oritable,..) returned:", a)for k,v in pairs(a) do print(k,v) endprint(string.rep('-',30))for k,v in pairs(getmetatable(oritable)) do print(k,v) end  :!lua setmetatable.luaoritable=       table: 0x1e4a830setmetable(oritable,..) returned:       table: 0x1e4a830------------------------------__mode  k

3.保护某个table的metatable不被再次修改：在该table(假设名字为mytable)的元表身上设置__metatable域，这样getmetatable(mytable)就会返回所设置的内容，setmetatable(mytable)会报错

[dongsong@localhost lua-study]$ cat setmetatable.lua oritable = {}local a = setmetatable(oritable, {__metatable='hello'})print("oritable=", oritable)print("setmetable(oritable,..) returned:", a)print("getmetatable(oritable) returned:", getmetatable(oritable))print("setmetatble(oritable,..) again:", setmetatable(oritable, {}))[dongsong@localhost lua-study]$ lua setmetatable.lua oritable=       table: 0x238a860setmetable(oritable,..) returned:       table: 0x238a860getmetatable(oritable) returned:        hellolua: setmetatable.lua:6: cannot change a protected metatablestack traceback:        [C]: in function 'setmetatable'        setmetatable.lua:6: in main chunk        [C]: ?

4.require package.path LUA_PATH

lua 5.1的官方文档 There were substantial changes in function require due tothe new module system.However, the new behavior is mostly compatible with the old,butrequire gets the path frompackage.path insteadof from LUA_PATH.

[dongsong@localhost require_test]$ tree -a.├── myfile2.lua├── mypackage│   └── myfile.lua└── test.lua1 directory, 3 files[dongsong@localhost require_test]$ cat test.luafunction test()        package.loaded['myfile2'] = nil        package.loaded['myfile'] = nil        print(string.rep("=",30))        print("package.path = ", package.path)        print("LUA_PATH = ", LUA_PATH)        local rt,msg =  pcall(require, "myfile2")        if type(msg) == 'string' then                local i,j                i,j,msg = string.find(msg, '([^\n]+)')        end        print("require myfile2:", rt, msg)        rt,msg = pcall(require, "myfile")        if type(msg) == 'string' then                local i,j                i,j,msg = string.find(msg, '([^\n]+)')        end        print("require myfile:", rt, msg)endtest()LUA_PATH = "/home/dongsong/data/lua-study/require_test/mypackage/?.lua"test()LUA_PATH = nilpackage.path = package.path .. ";/home/dongsong/data/lua-study/require_test/mypackage/?.lua"test()print(string.rep('=',30))for k,v in pairs(package.loaded) do print(k,v) end[dongsong@localhost require_test]$ [dongsong@localhost require_test]$ lua test.lua==============================package.path =  ./?.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;/usr/lib64/lua/5.1/?.lua;/usr/lib64/lua/5.1/?/init.luaLUA_PATH =      nilhello,i am myfile2require myfile2:        true    truerequire myfile: false   module 'myfile' not found:==============================package.path =  ./?.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;/usr/lib64/lua/5.1/?.lua;/usr/lib64/lua/5.1/?/init.luaLUA_PATH =      /home/dongsong/data/lua-study/require_test/mypackage/?.luahello,i am myfile2require myfile2:        true    truerequire myfile: false   module 'myfile' not found:==============================package.path =  ./?.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;/usr/lib64/lua/5.1/?.lua;/usr/lib64/lua/5.1/?/init.lua;/home/dongsong/data/lua-study/require_test/mypackage/?.luaLUA_PATH =      nilhello,i am myfile2require myfile2:        true    truehello,i am myfilerequire myfile: true    true==============================string  table: 0xa4d2c0debug   table: 0xa52640package table: 0xa4db50_G      table: 0xa4b6b0myfile  trueio      table: 0xa4f760os      table: 0xa50140table   table: 0xa4cbc0math    table: 0xa51570coroutine       table: 0xa4d600myfile2 true

dofile() loadfile() require()的区别

dofile()和loadfile()都不做所搜，require根据package.path来做搜索

dofile()编译文件并做执行，重复调用dofile()会重复编译和执行

loadfile()只是编译返回而不做执行，重复调用就重复编译

require()是搜索到文件并编译和执行，重复调用不会重复执行

[dongsong@localhost lua-study]$ luaLua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio> t=loadfile("t")> t()stdin:1: attempt to call global 't' (a nil value)stack traceback:        stdin:1: in main chunk        [C]: ?> t=loadfile("t.lua")> t()6> loadfile("t.lua")()6> t=dofile("t.lua")6> print(t)nil> dofile("t.lua")6> require("t.lua")stdin:1: module 't.lua' not found:        no field package.preload['t.lua']        no file './t/lua.lua'        no file '/usr/share/lua/5.1/t/lua.lua'        no file '/usr/share/lua/5.1/t/lua/init.lua'        no file '/usr/lib64/lua/5.1/t/lua.lua'        no file '/usr/lib64/lua/5.1/t/lua/init.lua'        no file './t/lua.so'        no file '/usr/lib64/lua/5.1/t/lua.so'        no file '/usr/lib64/lua/5.1/loadall.so'        no file './t.so'        no file '/usr/lib64/lua/5.1/t.so'        no file '/usr/lib64/lua/5.1/loadall.so'stack traceback:        [C]: in function 'require'        stdin:1: in main chunk        [C]: ?> require("t")    6> require("t")> [dongsong@localhost lua-study]$ cat t.luaa = {1,2,3,4,5,6}print(table.getn(a))

require返回值的问题：默认返回true,如果require的lua文件有return，则以其return的值作为require的返回值

[dongsong@localhost skynet]$ cat t.luaa = {1,2,3,4,5}print("i am required")[dongsong@localhost skynet]$ luaLua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio> t=require "t"i am required> =ttrue> =package.loaded["t"]true> ==============================================================[dongsong@localhost skynet]$ cat t.luaa = {1,2,3,4,5}print("i am required")return a[dongsong@localhost skynet]$ luaLua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio> pk=require "t"i am required> =pktable: 0x1427320> =package.loaded["t"]table: 0x1427320> for k,v in pairs(pk) do print(k,v) end1       12       23       34       45       5

5.注意elseif和else if的区别，后者在else下面的chunk里面启了新的if块，需要有与之对应的end

6.ipairs vs pairs

[dongsong@localhost lua-study]$ cat pairs.lua math.randomseed(os.time())t = {}for i = 1,10 do t[i] = i*i endfor i = 1,10 do        local v = math.random(1000)        t[v] = v*vendprint("ipairs(t):")print(string.rep('v',30))for k,v in ipairs(t) do print(k,v) endprint(string.rep('^',30))print("pairs(t):")print(string.rep('v',30))for k,v in pairs(t) do print(k,v) endprint(string.rep('^',30))[dongsong@localhost lua-study]$ [dongsong@localhost lua-study]$ lua pairs.lua ipairs(t):vvvvvvvvvvvvvvvvvvvvvvvvvvvvvv1       12       43       94       165       256       367       498       649       8110      100^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^pairs(t):vvvvvvvvvvvvvvvvvvvvvvvvvvvvvv1       12       43       94       165       256       367       498       649       8110      100580     336400852     725904854     729316678     459684804     646416188     35344346     119716824     678976771     594441511     261121^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

7.判断table是否为空

if next(myTable) == nil then   -- myTable is emptyend

参见：http://stackoverflow.com/questions/1252539/most-efficient-way-to-determine-if-a-lua-table-is-empty-contains-no-entries

8.貌似Lua没有类似于 php中的print_r()/var_dump(); python中的pprint.pprint() 这种函数。下面写了个简单的：

[root@test-22 lua-study]# cat pprint.lua local function pprint(var, tostr)        local duplicateTable = {}    local rstr = ''        local function realfunc(var, stack)                local function myprint(...)            rstr = rstr .. string.rep("\t",stack)            for _, s in pairs({...}) do                rstr = rstr .. s            end                end                if type(var) ~= "table" then                        myprint(tostring(var))                else                        --duplicate detect                        if duplicateTable[var] then                                myprint(tostring(var))                                return                        else                                duplicateTable[var] = 1                        end                        --print data                        myprint(tostring(var), "\n")            if var.__pprint and type(var.__pprint)=='function' then --把日志按照table返回(每行一个元素)                local tstrs = var:__pprint()                if type(tstrs) == 'table' then                <span style="white-space:pre"></span>for _, s in pairs(tstrs) do myprint(s,'\n') end                else                <span style="white-space:pre"></span>myprint(tstrs)                end            else                myprint("{")                local nilflag = true                for k,v in pairs(var) do                    if nilflag then                        rstr = rstr .. '\n'                        nilflag = false                    end                    realfunc(k, stack+1)                    if type(v) == "table" and next(v) ~= nil then                        rstr = rstr .. '=>\n'                        realfunc(v, stack+2)                    elseif type(v) ~= "table" then                        rstr = rstr .. '=>' .. tostring(v)                    else                        rstr = rstr .. '=>' .. tostring(v) .. '{}'                    end                    rstr = rstr .. '\n'                end                myprint("}")            end                end        end        realfunc(var, 0)    rstr = rstr .. '\n'    if tostr then return rstr else io.write(rstr) endendlocal d = {a=1, b=2, c={1,2,3,4}}local tmpd = {x=1,y={m=1,n=2}}d[tmpd] = {1,2,3,4,5,6,7,8,9,{"hello","world"}}d["hello"] = {}d["dup"] = dd[d] = "dup2"d.xx = {a=111, b=22,        __pprint = function(self)            local t = {}            table.insert(t, string.format('a=%d',self.a))            table.insert(t, string.format('b=%d',self.b))            return t        end        }print(pprint(d, true))[root@test-22 lua-study]# lua pprint.lua table: 0x16678140{        dup=>                table: 0x16678140        c=>                table: 0x1667cce0                {                        1=>1                        2=>2                        3=>3                        4=>4                }        b=>2        a=>1        hello=>table: 0x1667c160{}        xx=>                table: 0x16678000                a=111                b=22        table: 0x1667ac70        {                x=>1                y=>                        table: 0x1667acb0                        {                                n=>2                                m=>1                        }        }=>                table: 0x1667ad40                {                        1=>1                        2=>2                        3=>3                        4=>4                        5=>5                        6=>6                        7=>7                        8=>8                        9=>9                        10=>                                table: 0x1667c120                                {                                        1=>hello                                        2=>world                                }                }        table: 0x16678140=>dup2}

9.for迭代. 说白了，for中的表达式返回(函数，状态常量，控制变量)，每次循环用“状态常量”和“控制变量”作为参数调用“函数”，返回值赋给变量列表（第一项是下次循环的控制变量）。而多变量赋值和多参数赋值都遵循不足用nil补的原则。

[dongsong@localhost lua-study]$ cat iterator.lua local function allwords()    local line = io.read()   -- current line    local pos = 1            -- current position in the line    return function ()       -- iterator function       while line do        -- repeat while there are lines           local startpos, endpos = string.find(line, "%w+", pos)           if startpos then         -- found a word?              pos = endpos + 1   -- next position is after this word              return string.sub(line, startpos, endpos) -- return the word           else              line = io.read()  -- word not found; try next line              pos = 1       -- restart from first position           end       end       return nil    -- no more lines: end of traversal    endendio.input("test.txt")for word in allwords() do        print(word)end[dongsong@localhost lua-study]$ lua iterator.lua functionNumberOfGlocalcount0forninpairs

10.把table当普通c数组使用（PS: 交互模式下用=xx就可以直接打印变量xx，而不是必须用print()，这么简单的事情今天才发现，我了个大擦 2014.5.9）

> t = {}> table.insert(t, 123)> t[#t+1] = 456> = t[1]123> = t[2]456

用#table获取table的普通数组段的大小，这里有个小坑，须慎重！

> =atable: 0xfa52c0> for k,v in pairs(a) do print(k,v) end1       12       23       3> a[1] = nil> > for k,v in pairs(a) do print(k,v) end2       23       3> =#a3> a = {}> a[2] = 2> a[3] = 3> =#a0

上述的问题其实是因为table的普通数组部分被扩了，同时说明，普通数组部分的删除操作需要注意：

置nil之后数组部分大小没有改变(用#取到普通数组部分大小、不过用pairs和ipairs却无法遍历到相同数目的元素)；

而remove操作不同，它会改变数组部分大小同时会改变key和value的映射

> t={1,2,3,4}> t> =ttable: 0x15173e0> =#t4> table.remove(t,2)> =#t3> for k,v in pairs(t) do print(k,v) end1       12       33       4> table.insert(t,10)> for k,v in pairs(t) do print(k,v) end1       12       33       44       10

追加于2015.7.29

7849(孙晓辉) 2015-07-29 16:11:56local a = {}a[2] = 1a[3] = 1a[4] = 1print(#a)猜猜这个打印几？4281(许东松) 2015-07-29 16:11:550 或者 4 7849(孙晓辉) 2015-07-29 16:12:364

7849(孙晓辉) 2015-07-29 16:22:42它有个规则： 如果key的元素个数大于对应个数幂大小的一半，则生成对应幂长度的数组a[2] = 2 a[3] = 30~1 0个元素 0 > 2^0 / 2 不成立 数组长度00~2 1个元素 1 > 2^1 / 2 不成立 数组长度00~4 2个元素 2 > 2^2 / 2 不成立 数组长度0 7849(孙晓辉) 2015-07-29 16:23:19也就是说 # 和中间有没有nil 基本没啥关系7849(孙晓辉) 2015-07-29 16:23:28#只是单纯的返回数组部分长度吧

11.垃圾收集，数据清理，释放资源，c++对象析构

http://www.lua.org/manual/5.2/manual.html#2.5.1

local CMD = setmetatable({}, { __gc = function() netpack.clear(queue) end })

12.关于table遍历的问题

The behavior of next is undefined if, during the traversal, you assign any value to a non-existent field in the table. You may however modify existing fields. In particular, you may clear existing fields.
也就是说，在遍历过程中不能新增KEY，其他可以随便整

13.Lua date and time
参见 http://www.lua.org/pil/22.1.html

1>os.time(timeTable) 年月日必须指定，其他可选，时分秒默认是12:00:00.

2>os.date("*t",unittime) 得到的table中wday是：周日~周六->1~7

    os.date("%w",unixtime)得到的字符串是：周日~周六-> 0~6

3>os.date("*t",unixtime)得到的table中isdst是指是否使用夏时制，第一次了解这个概念，比较有意思（http://zh.wikipedia.org/wiki/%E5%A4%8F%E6%97%B6%E5%88%B6）

[dongsong@localhost lua-study]$ cat weekend.lua function getWeekZeroTime(time)    local zeros = os.date("return {year = %Y, month = %m, day = %d, week = %w}", time)    local zerot = loadstring(zeros)()    local weekv = zerot.week > 0 and (zerot.week - 1) or 6    zerot.week = nil    zerot.hour = 0 --warning: zerot.hour default 12    return os.time(zerot) - weekv*24*3600endfunction func(time)    local zerot = os.date('*t',time)    for k,v in pairs(zerot) do print(k,v) end    local w = tonumber(os.date('%w',os.time()))    print('%w->week:'..w)    print('*t->week:'..zerot.wday)    w = w>0 and w-1 or 6--or--w = (zerot.wday>1) and (zerot.wday-2) or 6    zerot.hour, zerot.min, zerot.sec = 0, 0, 0    return os.time(zerot) - w*24*3600endlocal t = os.time()print(getWeekZeroTime(t))print(string.rep('-',30))print(func(t))[dongsong@localhost lua-study]$ [dongsong@localhost lua-study]$ lua weekend.lua 1402848000------------------------------hour    19min     43wday    4day     18month   6year    2014sec     45yday    169isdst   false%w->week:3*t->week:41402848000

14.luarocks(http://luarocks.org/) 类似于python的easy_install

[dongsong@localhost ~]$ luarocks --helplua: /usr/local/bin/luarocks:3: module 'luarocks.loader' not found:        no field package.preload['luarocks.loader']        no file './luarocks/loader.lua'        no file '/usr/share/lua/5.1/luarocks/loader.lua'        no file '/usr/share/lua/5.1/luarocks/loader/init.lua'        no file '/usr/lib64/lua/5.1/luarocks/loader.lua'        no file '/usr/lib64/lua/5.1/luarocks/loader/init.lua'        no file './luarocks/loader.so'        no file '/usr/lib64/lua/5.1/luarocks/loader.so'        no file '/usr/lib64/lua/5.1/loadall.so'        no file './luarocks.so'        no file '/usr/lib64/lua/5.1/luarocks.so'        no file '/usr/lib64/lua/5.1/loadall.so'stack traceback:        [C]: in function 'require'        /usr/local/bin/luarocks:3: in main chunk        [C]: ?[dongsong@localhost ~]$ lua Lua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio> =package.path./?.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;/usr/lib64/lua/5.1/?.lua;/usr/lib64/lua/5.1/?/init.lua> package.path = package.path..";/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua"> require "luarocks.loader"[dongsong@localhost ~]$ export LUA_PATH='/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua' [dongsong@localhost ~]$ echo $LUA_PATH/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua[dongsong@localhost ~]$ luarocks --helpLuaRocks 2.1.2, a module deployment system for LuaNAME        /usr/local/bin/luarocks - LuaRocks main command-line interfaceSYNOPSIS        /usr/local/bin/luarocks [--from=<server> | --only-from=<server>] [--to=<tree>] [VAR=VALUE]... <command> [<argument>] ...

如何让lua自己去找到这个库，也就是不用每次都重设lua_path呢？

    At start-up, Lua initializes this variable with the value of the environment variable LUA_PATH or with a default path defined in luaconf.h, if the environment variable is not defined. Any ";;" in the value of the environment variable is replaced by the default path.

可见，除了在.bash_profile中设置LUA_PATH环境变量以外，还可以直接把需要追加的路径加到lua的配置文件中：我的机器是/usr/include/luaconf.h

15.luaprofiler(http://luaprofiler.luaforge.net/manual.html) 类似于测试c++程序的google-perftools. 暂时还没实际使用过。

16.print(t) string.format('%s',t) tostring(t) 对于table t, 默认会输出“table address", 这里调用的是元表的__tostring方法，如果改写了这个方法，那么要获取一个table的地址就不容易了（google没找到解决办法，还是Python容易，直接id(t)就行了）,所以要想得到地址可以在改写__tostring方法之前用tostring(t)获取后放在t身上。（剑雄客户端middleclass区分同类型粒子的不同实例就是这么干的）

17.Lua 垃圾收集 GC

http://blog.csdn.net/yuanlin2008/article/details/8558103 简明的文章

18.关于pcall和异常传播

对可能有异常的lua函数f使用pcall(f)，那么f内出现异常也不会中断程序

如果在lua中调用自己编写的c lib的函数f，而函数内有异常，那么程序会在异常处中断，就算pcall(f)程序还是会中断

19.lua判断空格等空串

[dongsong@localhost lua-study]$ cat emptystr.lua function isBlank(x)  return not not x:find("^%s*$")endprint(isBlank('  '))print(isBlank('  \n'))print(isBlank('\t '))print(isBlank('; '))[dongsong@localhost lua-study]$ lua emptystr.lua truetruetruefalse

20.优先级从高到低 http://www.lua.org/pil/3.5.html

             ^             not  - (unary)             *   /             +   -             ..             <   >   <=  >=  ~=  ==             and             or

21.闭包(2015.4.30）,跟python类似(参见http://blog.csdn.net/xiarendeniao/article/details/6774520  <item61>)，前两天客户端同事在for外面定义变量a，每次给a赋值并为a常见一个button(细节不了解，应该是个闭包用于回调），结果所有button点击时发了相同的数据。下面这个小程序对闭包的解释应该够明了了。

[dongsong@localhost lua-study]$ cat upvalue_test_2.lua local function func()    local funcs = {}    local a    for index = 1, 5 do        a = index        local function func_enclosing()            io.write(string.format('enclosing func %s %d\n', tostring(func_enclosing), a))        end        table.insert(funcs, func_enclosing)    end    return funcsendlocal funcs = func()for _, tfunc in pairs(funcs) do    io.write(tostring(tfunc), '\n  ')    tfunc()end[dongsong@localhost lua-study]$ lua upvalue_test_2.lua function: 0x13ce160  enclosing func function: 0x13ce160 5function: 0x13cec60  enclosing func function: 0x13cec60 5function: 0x13cdd70  enclosing func function: 0x13cdd70 5function: 0x13ce750  enclosing func function: 0x13ce750 5function: 0x13ce790  enclosing func function: 0x13ce790 5

22.sleep

linux & windows. cpu消耗大function Sleep(n)   local t0 = os.clock()   while os.clock() - t0 <= n do endendlinuxfunction Sleep(n)   os.execute("sleep " .. n)endwindowsfunction Sleep(n)   if n > 0 then os.execute("ping -n " .. tonumber(n + 1) .. " localhost > NUL") endend

23.热更时获取upvalue

local func = packetHandler[opCodes.G2D_ARENA_CHAR_JOIN]local isMainThread = falsefor index = 1, 10 do        local upname, upvalue = debug.getupvalue(func, index)        if not upname then break end        if upname == 'charIdToRank' and next(upvalue) then isMainThread = true; break endendif not isMainThread then print("i'm not main thread"); return endprint("i'm main thread")--do return end

24.lua bit32 (5.3版不提倡使用)  对于大于32bit的整数高位被清除了

> a = 0x7fffffffffffffff> =a9223372036854775807> =bit32.band(a,0x7ffffffffffffff0)4294967280> return bit32.band(0xffffffff,0xfffffff0)        4294967280

25.for 语法制造for作用域之内有效的local变量

[root@test-22 lua-study]# cat fortest.lua local function test()    local m, n = 1, 1    print(string.format('---m(%s) n(%s)', m, n))    while m < 10 do print(string.format('while m(%s)', m)); m = m+1 end    for n = 1, 10 do print(string.format('for n(%s)', n)) end    print(string.format('---m(%s) n(%s)', m, n))endtest()[root@test-22 lua-study]# lua fortest.lua ---m(1) n(1)while m(1)while m(2)while m(3)while m(4)while m(5)while m(6)while m(7)while m(8)while m(9)for n(1)for n(2)for n(3)for n(4)for n(5)for n(6)for n(7)for n(8)for n(9)for n(10)---m(10) n(1)