print()
print("Hi")
-- You can omit parentheses if the argument is one string or table literal
print "Hello World" <--> print("Hello World")
dofile 'a.lua' <--> dofile ('a.lua')
print [[a multi-line <--> print([[a multi-line
message]] message]])
f{x=10, y=20} <--> f({x=10, y=20})
type{} <--> type({})
t = {}
t = { a = 1, b = 2 }
t.a = function() ... end
t = { ["hello"] = 200 }
t.hello
-- Remember, arrays are also tables
array = { "a", "b", "c", "d" }
print(array[2]) -- "b" (one-indexed)
print(#array) -- 4 (length)
while condition do
end
for i = 1,5 do
end
for i = start,finish,delta do
end
for k,v in pairs(tab) do
end
repeat
until condition
-- Breaking out:
while x do
if condition then break end
end
if condition then
print("yes")
elseif condition then
print("maybe")
else
print("no")
end
function myFunction()
return 1
end
function myFunctionWithArgs(a, b)
-- ...
end
myFunction()
anonymousFunctions(function()
-- ...
end)
-- Not exported in the module
local function myPrivateFunction()
end
-- Splats
function doAction(action, ...)
print("Doing '"..action.."' to", ...)
--> print("Doing 'write' to", "Shirley", "Abed")
end
doAction('write', "Shirley", "Abed")
mytable = { x = 2, y = function() .. end }
-- The same:
mytable.x
mytable['x']
-- Syntactic sugar, these are equivalent:
mytable.y(mytable)
mytable:y()
mytable.y(mytable, a, b)
mytable:y(a, b)
function X:y(z) .. end
function X.y(self, z) .. end
mt = {}
-- A metatable is simply a table with functions in it.
mt.__tostring = function() return "lol" end
mt.__add = function(b) ... end -- a + b
mt.__mul = function(b) ... end -- a * b
mt.__index = function(k) ... end -- Lookups (a[k] or a.k)
mt.__newindex = function(k, v) ... end -- Setters (a[k] = v)
-- Metatables allow you to override behavior of another table.
mytable = {}
setmetatable(mytable, mt)
print(myobject)
Account = {}
function Account:new(balance)
local t = setmetatable({}, { __index = Account })
-- Your constructor stuff
t.balance = (balance or 0)
return t
end
function Account:withdraw(amount)
print("Withdrawing "..amount.."...")
self.balance = self.balance - amount
self:report()
end
function Account:report()
print("Your current balance is: "..self.balance)
end
a = Account:new(9000)
a:withdraw(200) -- method call
-- Relational (binary)
-- __eq __lt __gt __le __ge
== < > <= >=
~= -- Not equal, just like !=
-- Arithmetic (binary)
-- __add __sub __muv __div __mod __pow
+ - * / % ^
-- Arithmetic (unary)
-- __unm (unary minus)
-
-- Logic (and/or)
nil and false --> nil
false and nil --> false
0 and 20 --> 20
10 and 20 --> 20
-- Length
-- __len(array)
#array
-- Indexing
-- __index(table, key)
t[key]
t.key
-- __newindex(table, key, value)
t[key]=value
-- String concat
-- __concat(left, right)
"hello, "..name
-- Call
-- __call(func, ...)
dofile("hello.lua")
loadfile("hello.lua")
assert(x) -- x or (raise an error)
assert(x, "failed")
type(var) -- "nil" | "number" | "string" | "boolean" | "table" | "function" | "thread" | "userdata"
-- Does /not/ invoke meta methods (__index and __newindex)
rawset(t, index, value) -- Like t[index] = value
rawget(t, index) -- Like t[index]
_G -- Global context
setfenv(1, {}) -- 1: current function, 2: caller, and so on -- {}: the new _G
pairs(t) -- iterable list of {key, value}
ipairs(t) -- iterable list of {index, value}
tonumber("34")
tonumber("8f", 16)
'string'..'concatenation'
s = "Hello"
s:upper()
s:lower()
s:len() -- Just like #s
s:find()
s:gfind()
s:match()
s:gmatch()
s:sub()
s:gsub()
s:rep()
s:char()
s:dump()
s:reverse()
s:byte()
s:format()
table.foreach(t, function(row) ... end)
table.setn
table.insert(t, 21) -- append (--> t[#t+1] = 21)
table.insert(t, 4, 99)
table.getn
table.concat
table.sort
table.remove(t, 4)
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.ldexp math.log
math.log10 math.max math.min math.modf math.pow
math.rad math.random math.randomseed math.sin math.sinh
math.sqrt math.tan math.tanh
math.sqrt(144)
math
io.output(io.open("file.txt", "w"))
io.write(x)
io.close()
for line in io.lines("file.txt")
file = assert(io.open("file.txt", "r"))
file:read()
file:lines()
file:close()