在线笔记
全部博文（596）
分类： Python/Ruby
2012-12-06 15:06:56
注：以下例子选自LuaForWindows(LFW)组件QuickLuaTour，对其中做了一些主要的翻译并加上了个人的理解注释，没有安装过LFW的朋友可以一看，虽然例子很简单，但是对初学者快速入门会有所帮助。
关键词：Lua、Lua实例、QuickLuaTour、LFW、Lua入门
-- Example 1 -- First Program.
-- Classic hello program.
print("hello")
-------- Output ------
Hello
-- Example 2 -- Comments. 注释
--单行注释以双连字符“--”开头多行注释“—[[”以开始，以“]]”结束
-- Single line comments in Lua start with double hyphen.
--[[ Multiple line comments start
with double hyphen and two square brackets.
and end with two square brackets. ]]
-- And of course this example produces no
-- output, since it's all comments!
-------- Output ------
-- Example 3 -- Variables.
-- Variables hold values which have types, variables don't have types.
--变量的值拥有类型，变量没有类型
a=1
b="abc"
c={}
d=print
print(type(a))
print(type(b))
print(type(c))
print(type(d))
-------- Output ------
number
string
table
function
-- Example 4 -- Variable names. 变量命名
-- Variable names consist of letters, digits and underscores.
-- They cannot start with a digit.
-- 变量的名称由字母、数字、下划线组成，但是不能以数字开始
one_two_3 = 123 -- is valid varable name --合法命名
-- 1_two_3 is not a valid variable name. --以数字开始，不合法
-------- Output ------
-- Example 5 -- More Variable names.
--[[ 在Lua中以下划线”_”开始的参数命名通常代表特殊的值，如（“_VERSION”），所以尽量不用使用以下划线开始命名。当时通常单个“_”代表虚假的参数。注：这是Lua的一个语法，后面将讲到，如：local _, x = string.find(s, p) ]]-- The underscore is typically used to start special values
-- like _VERSION in Lua.
print(_VERSION)
-- So don't use variables that start with _,
-- but a single underscore _ is often used as a
-- dummy variable.
-------- Output ------
-- Example 6 -- Case Sensitive. 大小写敏感
-- Lua is case sensitive so all variable names & keywords
-- must be in correct case.
-- 在Lua中所有的变量和关键字都是大小写敏感的
ab=1
Ab=2
AB=3
print(ab,Ab,AB)
-------- Output ------
1 2 3
-- Example 7 -- Keywords. Lua关键字
--[[ Lua的关键字大家可以去参考“Lua Reference Manual”，附：5.1版本的参考手册在线地址： 变量命名的时候应避免使用关键字,应Lua是大小写敏感的，所以“and”是关键字，但“AND”不是是合法的命名，尽管如此，建议大家尽量不要用关键词(各种大小写版本)]]
-- Lua reserved words are: and, break, do, else, elseif,
-- end, false, for, function, if, in, local, nil, not, or,
-- repeat, return, then, true, until, while.
-- Keywords cannot be used for variable names,
-- 'and' is a keyword, but AND is not, so it is a legal variable name.
AND=3
print(AND)
-------- Output ------
3
-- Example 8 -- Strings.
--[[字符串可以用双引号（“”）也可以用单引号（‘’），类似于JavaScript语法，对于多行字符串，使用“[[ ]]”括起来 ]]
a="single 'quoted' string and double \"quoted\" string inside"
b='single \'quoted\' string and double "quoted" string inside'
c= [[ multiple line
with 'single'
and "double" quoted strings inside.]]
print(a)
print(b)
print(c)
-------- Output ------
single 'quoted' string and double "quoted" string inside
single 'quoted' string and double "quoted" string inside
multiple line
with 'single'
and "double" quoted strings inside.
-- Example 9 -- Assignments. 赋值
--[[可以一次对多个变量赋值，规则：如果等号（“=”）右边多了，则舍弃，左边多了，则赋值为空（nil） ]]
-- Multiple assignments are valid.
-- var1,var2=var3,var4
a,b,c,d,e = 1, 2, "three", "four", 5
print(a,b,c,d,e)
-------- Output ------
1 2 three four 5
-- Example 10 -- More Assignments.
-- Multiple assignments allows one line to swap two variables.
-- 表达式 a,b=b,a表示a和b的值交换
print(a,b)
a,b=b,a
print(a,b)
-------- Output ------
1 2
2 1
-- Example 11 -- Numbers.
-- Multiple assignment showing different number formats.
-- Two dots (..) are used to concatenate strings (or a
-- string and a number). – 在Lua中两点“..”表示字符串连接，对应其他语言中的“+”连接
a,b,c,d,e = 1, 1.123, 1E9, -123, .0008
print("a="..a, "b="..b, "c="..c, "d="..d, "e="..e)
-------- Output ------
a=1 b=1.123 c=1000000000 d=-123 e=0.0008
-- Example 12 -- More Output.
-- More writing output. –多种输出方式或写法
print "Hello from Lua!" -- 不带括号
print("Hello from Lua!") -- 带括号，两者等价
-------- Output ------
Hello from Lua!
Hello from Lua!
--[[什么时候可以省略括号? 这是以种特殊的情况，只有当函数的参数只有一个，而且这个参数是字面上的字符串串（a literal string:即直接传字符串，而不是值为字符串的参数变量）或者蚕食是table结构。这两种情况才可以省略圆括号]]
-- Example 14 -- Tables.
-- 表结构在Lua中特别常见，可以存储任何类型，很灵活。非常类似于JS中的一个对象。
-- Simple table creation.
a={} -- {} creates an empty table
b={1,2,3} -- creates a table containing numbers 1,2,3
c={"a","b","c"} -- creates a table containing strings a,b,c
print(a,b,c) -- tables don't print directly, we'll get back to this!!
-------- Output ------
table: 00410A58 table: 00410E90 table: 00410FB8
-- Example 15 -- More Tables.
-- Lua中表结构和JS中的对象一样可以随时增加或删除（直接赋值nil）属性。
--[[ 读取有多种方式，可以用点“.”的方式，也可以用索引index,不过在Lua有点特殊，首先索引是从一开始，其次index=1并不一定是第一个元素值，比如下面的address[1]=nil，而不是“Wyman Street”,具体的以后在讲]]
-- Associate index style.
address.Street="Wyman Street"
address.StreetNumber=360
address.AptNumber="2a"
address.City="Watertown"
address.State="Vermont"
address.Country="USA"
print(address.StreetNumber, address["AptNumber"])
-------- Output ------
360 2a
-- Example 16 -- if statement. if语句
-- Lua中的语句块语法有点类似VB都是以end结束
-- Simple if.
a=1
if a==1 then
print ("a is one")
end
-------- Output ------
a is one
-- Example 17 -- if else statement.
b="happy"
if b=="sad" then
print("b is sad")
else
print("b is not sad")
end
-------- Output ------
b is not sad
-- Example 18 -- if elseif else statement
-- 需要注意的是“elseif” 是连在一起的，这个和C#的 else if 不同
c=3
if c==1 then
print("c is 1")
elseif c==2 then
print("c is 2")
else
print("c isn't 1 or 2, c is "..tostring(c))
end
-------- Output ------
c isn't 1 or 2, c is 3
-- Example 19 -- Conditional assignment. 条件语句
-- value = test and x or y
--注：value = test and x or y 等价于我们平时写的三元运算符（“？:”)的效果 value= test?x:y
a=1
b=(a==1) and "one" or "not one"
print(b)
-- is equivalent to
a=1
if a==1 then
b = "one"
else
b = "not one"
end
print(b)
-------- Output ------
one
one
-- Example 20 -- while statement.
-- while语句
a=1
while a~=5 do -- Lua uses ~= to mean not equal
a=a+1
io.write(a.." ")
end
-------- Output ------
2 3 4 5
-- Example 21 -- repeat until statement.
a=0
repeat
a=a+1
print(a)
until a==5
-------- Output ------
1
2
3
4
5
-- Example 22 -- for statement.
-- for语句有两种变体，一种叫 Numeric for ,一种叫 Generic for 就是例23中的for…in结构
--[[ Numeric for 的语法为：
for var=exp1,exp2,exp3 do something end
等价于C#中的：for(int i=exp1; i<=exp2; i+=exp3) { something }
]]
-- Numeric iteration form.
-- Count from 1 to 4 by 1.
for a=1,4 do io.write(a) end
print()
-- Count from 1 to 6 by 3.
for a=1,6,3 do io.write(a) end
-------- Output ------
1234
14
-- Example 23 -- More for statement.
-- for语句的Generic for变体
-- Sequential iteration form.
for key,value in pairs({1,2,3,4}) do print(key, value) end
-------- Output ------
1 1
2 2
3 3
4 4
-- Example 24 -- Printing tables.
-- 用简单的方式遍历table结构，并输出
-- Simple way to print tables.
a={1,2,3,4,"five","elephant", "mouse"}
for i,v in pairs(a) do print(i,v) end
-------- Output ------
1 1
2 2
3 3
4 4
5 five
6 elephant
7 mouse
-- Example 25 -- break statement.
-- break is used to exit a loop.
-- break关键字用于跳出循环，当然return也可以，不过有区别
a=0
while true do
a=a+1
if a==10 then
break
end
end
print(a)
-------- Output ------
10
-- Example 26 -- Functions.
-- 最简单的函数调用
-- Define a function without parameters or return value.
function myFirstLuaFunction()
print("My first lua function was called")
end
-- Call myFirstLuaFunction.
myFirstLuaFunction()
-------- Output ------
My first lua function was called
-- Example 27 -- More functions.
--[[ 带返回值的函数调用，大家注意a=mySecondLuaFunction("string")带了一个参数，但是mySecondLuaFunction定义并没有带参数，这个在Lua比较松，会直接忽略，即使你多写几个也没关系。]]
-- Define a function with a return value.
function mySecondLuaFunction()
return "string from my second function"
end
-- Call function returning a value.
a=mySecondLuaFunction("string")
print(a)
-------- Output ------
string from my second function
-- Example 28 -- More functions.
--[[ 使用函数返回值对多个变量赋值，规则和多参数赋值一样，如果函数返回值多了，则抛弃，少了则少的赋值为nil ]]
-- Define function with multiple parameters and multiple return values.
function myFirstLuaFunctionWithMultipleReturnValues(a,b,c)
return a,b,c,"My first lua function with multiple return values", 1, true
end
a,b,c,d,e,f = myFirstLuaFunctionWithMultipleReturnValues(1,2,"three")
print(a,b,c,d,e,f)
-------- Output ------
1 2 three My first lua function with multiple return values
1 true
-- Example 29 -- Variable scoping and functions. 变量作用域
--[[ 在Lua中，默认声明的变量为全局变量，以local 为修饰符的为局部变量，局部变量只在所属的语句块内有效]]
-- All variables are global in scope by default.
b="global"
-- To make local variables you must put the keyword 'local' in front.
function myfunc()
local b=" local variable"
a="global variable"
print(a,b)
end
myfunc()
print(a,b)
-------- Output ------
global variable local variable
global variable global
-- Example 30 -- Formatted printing. 字符串格式
--[[ 字符串格式大家可以去参考Lua参考手册“Lua Reference Manual” 这里重点说明一下在这些例子中第一次见到三个点“…”的作用，在Lua中在函数的参数列表中，表示参数的格式是可变不固定的，当这个函数在被调用时，函数的所有参数都被存储在一个名为arg的表结构中，同时arg还有一个n属性，代表实际传人的可变参数的个数，那么可以通过arg来访问所有的可变参数了，细节的以后再讲]]
-- An implementation of printf.
function printf(fmt, ...)
io.write(string.format(fmt, ...))
end
printf("Hello %s from %s on %s\n",
os.getenv"USER" or "there", _VERSION, os.date())
-------- Output ------
Hello there from Lua 5.1 on 08/11/11 16:48:19
-- Example 31 --[[
Standard Libraries
Lua has standard built-in libraries for common operations in
math, string, table, input/output & operating system facilities.
External Libraries
Numerous other libraries have been created: sockets, XML, profiling,
logging, unittests, GUI toolkits, web frameworks, and many more.
]]
-------- Output ------
-- Example 32 -- Standard Libraries - math. Lua中标准的数学函数
--[[详细请参考Lua参考手册“Lua Reference Manual” ]]
-- Math functions:
-- math.abs, math.acos, math.asin, math.atan, math.atan2,
-- math.ceil, math.cos, math.cosh, math.deg, math.exp, math.floor,
-- math.fmod, math.frexp, math.huge, math.ldexp, math.log, math.log10,
-- math.max, math.min, math.modf, math.pi, math.pow, math.rad,
-- math.random, math.randomseed, math.sin, math.sinh, math.sqrt,
-- math.tan, math.tanh
-------- Output ------
3 3.1415926535898
-- Example 33 -- Standard Libraries - string. Lua中string类库
-- String functions:
-- string.byte, string.char, string.dump, string.find, string.format,
-- string.gfind, string.gsub, string.len, string.lower, string.match,
-- string.rep, string.reverse, string.sub, string.upper
print(string.upper("lower"),string.rep("a",5),string.find("abcde", "cd"))
-------- Output ------
LOWER aaaaa 3 4
-- Example 34 -- Standard Libraries - table. Lua中的table类库
-- Table functions:
-- table.concat, table.insert, table.maxn, table.remove, table.sort
a={2}
table.insert(a,3);
table.insert(a,4);
table.sort(a,function(v1,v2) return v1 > v2 end)
for i,v in ipairs(a) do print(i,v) end
-------- Output ------
1 4
2 3
3 2
-- Example 35 -- Standard Libraries - input/output. 输入输出
--[[其中：io.write函数和print函数的功能相同都是输出显示，只是io.write输出后不换行]]
-- IO functions:
-- io.close , io.flush, io.input, io.lines, io.open, io.output, io.popen,
-- io.read, io.stderr, io.stdin, io.stdout, io.tmpfile, io.type, io.write,
-- file:close, file:flush, file:lines ,file:read,
-- file:seek, file:setvbuf, file:write
print(io.open("file doesn't exist", "r"))
-------- Output ------
nil file doesn't exist: No such file or directory 2
-- Example 36 -- Standard Libraries - operating system facilities. 操作系统中类库
-- OS functions:
-- os.clock, os.date, os.difftime, os.execute, os.exit, os.getenv,
-- os.remove, os.rename, os.setlocale, os.time, os.tmpname
print(os.date())
-------- Output ------
08/11/11 17:07:30
-- Example 37 -- External Libraries. 扩展类库
-- Lua has support for external modules using the 'require' function
-- INFO: A dialog will popup but it could get hidden behind the console.
require( "iuplua" )
ml = iup.multiline
{
expand="YES",
value="Quit this multiline edit app to continue Tutorial!",
border="YES"
}
dlg = iup.dialog{ml; title="IupMultiline", size="QUARTERxQUARTER",}
dlg:show()
print("Exit GUI app to continue!")
iup.MainLoop()
-------- Output ------
-- Example 38 --[[
-- 后续学习lua-users wiki
To learn more about Lua scripting see
Lua Tutorials:
"Programming in Lua" Book:
Lua 5.1 Reference Manual:
Start/Programs/Lua/Documentation/Lua 5.1 Reference Manual
Examples: Start/Programs/Lua/Examples
]]
-------- Output ------
http://xuzhihong1987.blog.163.com/blog/static/26731587201171152614685/
