lua自带的Example（一）

--Example 1
-- First program
-- classic hello program

print("hello)


----------OutPut-----
hello


--Example 2
--comments
--Single comments in lua start with double hypen

--[[ Multiple line comments start
with double hypen and two square brackets.
and end with two square brackets. ]]

--Single line comments

--And of course this example produce no
--output because of the comments

-----Output------------

-Example 3
--Variables
--Variables hold value which have types,but in lua Variables donot have types
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
--Variables names consist of letters, digits and underscores
--They connot start with a digit

one_two_3 = 123 -- is a valid varable name

-- 1_one_two is not valid varable name

------Output------

--Example 5
--More Variable names
--The underscore is typically used to start special values
--like _VERSION in lua

print(_VERSION)

--So donot use variable that start with _
--but a single underscore _ is often used as a
--dummy variable

-------------Output------

Lua 5.1

--Example 6
--Case Sensitive
--Lua is case Sensitive so all variable name & keywords
--must be correct case

ab = 1
Ab = 2
AB = 3
print(ab, Ab, AB)

------------Output---------
1   2   3

-Example 7
--keywords
--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 connot be used for variable names
-- 'and' is a keyword, but And is not, so it can be a varable name

And = 3
print(And)

------------Output----------

3


--Example 8
--Strings

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
--Assigments
--Multiple Assigments 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 Assigments allows one line to swap two variables.
a = 1
b = 2
print(a, b)
a, b = b, a
print(a, b)

------------Output---------------

1    2
2    1

--Example 11
--numbers
--Multiple Assigments showing different number formats.
--Two dots<..> are used to concatenate string or a string and a number

a, b, c, d, e = 1, 1.123, 1E9, -123, .000
print("a="..a, "b="..b, "c="..c, "d="..d, "e="..e)


---------------Output-------------

a=1    b=1.123    c=10000000   d=-123   e=0.000


--Example 12
--More Output
--More writing output

print "hello for Lua!"
print ("hello for Lua!")


----------------Output--------------
hello for
hello for