[Lua]lua初识

关于函数

day1

--[[function fuc(n)

if n==0 then
return 1
else
return n*fuc(n-1)
end
end

print("input a number")
a = io.read("*number")
print(fuc(a))
--]]

--替换字符串
--[[
a = "one thing"
b = string.gsub(a,"one","two")
print(a)
print(b)
--]]

--转换数字
--[[
line = io.read()
n = tonumber(line)
if n==nil then
error(line.."is not a valid number")
else
print(n*2)
end
--]]

 

--拼接字符串
--[[
print("10"+1)

print("hell".."o")
--]]

--转换
--[[
line = io.read()
n = tonumber(line)
print(n)

print("我是一个字符串"..tostring(n))

print("10"=="10")
print(tostring(10)=="10")
--]]

--#计算长度
--[[
a = "hello"
print(#a)
print(#"good\0byte")
]]--

--table的使用
--[[
a = {}
k = "x"
a[k] = 10
a[20] = "great"
print(a[k])
print(a[20])
k = 20
print(a[k])
a["x"] =a["x"]+1
print(a["x"])

--使用同一个table
a = {}
a["x"] = 10
b = a --a和b使用了同一个table
print(b["x"])
b["x"] = 20
print(a["x"])
a = nil --b还在用table
b = nil --没人用table了

--自动增长
a = {}
--创建1000个新条目
for i = 1,1000 do a[i] = i*2 end
print(a[9])
a["x"] = 10
print(a["x"])
print(a["y"])
a.x = 20
print(a["x"])
print(a.x)

--循环存储值
a = {}
for i = 1,10
do a[i] = io.read() end

--输入打印数组的值
for i = 1,#a do
print(a[i])
end
--输出最后一个值
print(a[#a])
a[#a] = nil --删除最后一个值
a[#a + 1] = v --将v添加到列表的末尾
--]]

--[[
a = {}
a[1000] = 10
a[10000] = 11
print(table.maxn(a))

a = {}
i = 10;j = "10";k = "+10"
a[i] = "one value"
a[j] = "another value"
a[k] = "yet another value"
print(a[i])
print(a[j])
print(a[k])
print(a[tonumber(j)])
print(a[tonumber(k)])
--]]

--取小数点后面几位
--[[
x = math.pi
print(x%0.1)
print(x - x%0.01)

local tolerance = 10
function isturnback(angle)
angle = angle%360
return (math.abs(angle-180)<tolerance)
end
print(isturnback(-180))
--]]

--[[
a = 10
b = "10"
if tostring(a)~=b then print("不等")
else
print("相等")
end
--]]

--[[
a = {}
a.x = 1
a.y = 2
b = {}
b.x = 1
b.y = 2
c = a --a 等于 c table只有两个变量引用同一个的时候才是相等的
if a==b then print("a==b")
else
print("a~=b")
end
--]]

--[[

days = {"Sunday","Monday","Tuesday","Wednessday","Thursday","Friday","Saturday"}
print(days[1]) --这里注意不是从0开始

--a={x = 10,y = 20} <=>a = {};a.x = 10;a.y = 20

w = {x = 0,y = 0, label = "console"}
x = {math.sin(0),math.sin(1),math.sin(2)}
w[1] = "anther field"
x.f = w
print(w["x"])
print(w[1])
print(x.f[1])
w.x = nil
--]]

--[[
list = nil
for line in io.lines() do
list = {next = list,value = line}
end

local l = list
while l do
print(l.value)
l = l.next
end
--]]

--error("inva operation")

--相当于do while
--[[
repeat
line = io.read()
until line ~=""
print(line)

for i = 1,math.huge do --math.huge 无限大
print(1)
end
--]]

 

--[[
days = {"Sunday","Monday","Tuesday","Wednessday","Thursday","Friday","Saturday"}

revDays = {["Sunday"] = 1,["Monday"] = 2,["Tuesday"] = 3,["Wednessday"] = 4,["Thursday"] = 5,["Friday"] = 6,["Saturday"] = 7}
x = "Tuesday"
--print(revDays[x])

table.sort(revDays)
revDays1 = {}
for k,v in pairs(revDays) do --给v赋值“Sunday","Monday"... k赋值1，2...
print(k)
print(v)
end

--数组排序
a = {1,3,2}
table.sort(a)
for i,v in pairs(a) do print(v) end

--]]

--print("Monday是第"..revDays1["Monday"].."天")

--[[
for key,value in ipairs(revDays1) do
print(revDays1[key])
end
--]]

--[[
a = {}
a[1] = 10
a[2] = 20
a[3] = 30
for i,v in pairs(a) do print(v) end
--]]

 

 

day2

--函数
--数组求和

--[[
function sum(a)
local sum = 0
for i,v in pairs(a) do
sum = sum + v
end
return sum
end

a = {1,2,3,4,5,6}
num = sum(a)
print(num)

s,e = string.find("hello lua","lua")
print(s,e) --返回函数的开始结束字符，从1开始

--]]

--返回多个返回值
--[[
function maximum(a)
local mi = 1
local m = a[mi]
for i,val in pairs(a) do
if val> m then
mi = i;m = val
end
end
return m,mi
end
--]]

--[[
function maxmum(a)
local num = 1
local val = a[num]
for i,value in pairs(a) do
if value>val then
num = i
val = value
end
end
return val,num
end

print(maxmum({8,10,23,12,5}))
--]]

t = {}
s = "from=world, to=Lua"
for k, v in string.gmatch(s, "(%w+)=(%w+)") do
t[k]=v
end
for k, v in pairs(t) do
print(k,v)
end

 

print({if not package.loaded["111"] then print("nil") end}

 

 

day3

 

--面向对象

People = {} --定义一个p表

function clone(tab)
local t = {}
for key,value in pairs(tab) do
t[key] = value
end
return t
end

--[[
function People.sayhi()
print("Hello World")
end--]]

--[[People.sayhi = function()
print("Hello People ")
end--]]

function People.new(name)
local self = clone(People)
self.name = name
return self
end

People.sayhi = function(self)
print("Hello People "..self.name)
end

--[[q = clone(People)
q.sayhi()--]]

local k = People.new("丁小未")
k.sayhi(k)
k:sayhi(k)
--k.sayhi()

 

--继承

function copy(dist,tab)
for key,value in pairs(tab) do
dist[key] = value
end
end

Man = {}

Man.new = function(name)
local self = People.new(name)
copy(self,Man)
return self
end

Man.sayHello = function()
print("Man say hello")
end

Man.sayhi = function(self)
print("hi "..self.name)
end

local m= Man.new("人")
m.sayhi(m)
m:sayHello()
--m:sayhi(m)

 

 

 

lua不支持函数重载

 

--可变参数

function show(...)
local num = select('#',...)
if num>0 then
print("恩")
else
print("无")
end
end

show()

 

function clone(tab)
local t = {}
for key,value in pairs(tab) do
t[key] = value
end
return t
end

--[[
function People.sayhi()
print("Hello World")
end--]]

 

function People.new(name)
local self = clone(People)
self.name = name
return self
end

People.sayhi = function(self)
print("Hello People "..self.name)
end

 

local k = People.new("丁小未")
k.sayhi(k)

 

 

--原表

local tbA = {a = 1}
local tbB = {b = 2}
tbA.y = function(tb, k) --必须要有返回值
print("__index key:" .. k)
if k == 'a' then
return 10
end
return nil
end
--[[
local mt = {__index = tbA,
__newindex = function(t, k, v)
end
}

local mt = {__index = function(tb, k)   --这个元方法用于读取值
print("__index key:" .. k)
if k == 'a' then
return 10
end
return nil
end,
__newindex = function(tb, k, v)  --这个是用于设置值
print("__newindex key:" .. k)
end
}
]]
setmetatable(tbB, tbA)
tbB.a = 3
print(tbB.a)
--tbB.d = 3
--tbB.b = 5
--print(tbB.d)