samuelfvlcastro/cheatsheet.lua

## cheatsheet.lua
-- Variables
v1, v2, v3 = 3, 2, 1
print(v1,v2,v3, v4 --[[by default it's nil]])

v5, v6, v7 = true, 1, 0 -- Are all "true" values
v8, v9 = false, nil -- Are the only "false" values

--[[ Operators
1 - The logical AND, OR, and NOT
2 - The inequality operator is ~= instead of !=.
3 - .. is the operator for string concatenation.
4 - ^ raises a number to a power
5 - # is an operator used to get the length of tables and strings
]]


-- Conditionals
if state == 5 then
  print(state)
end


-- Loops
while x < 10 do
  x = x + 2
  print(x)
end

while true do
  print("run once")
  break
end

i = 5
repeat
  i = i - 1
  print(i)
until i == 1

for i = 1, 11, 2 do -- for var = start, limit, step do
  x = x * i
  print(x)
end

if pcall(function () print(a[i]) end) then -- protected function call
  print("cool")
else
  print("error")
end

error("string expected") -- throw error


-- Generic for loops
days = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
b = { 20, 30, 40 }

for key, value in pais(days) do
  print(key, value)
end

for index, value in ipairs(b) do
  print(index, value)
end


-- Functions
function first(v1, v2)
  local x, y = second(v1 or 1, v2 or 2)
  print(x, y)
end
function second(v1, v2)
  return v1+1, v2+1
end
first(2, 3)
first() -- the "or" works as a optional value alternative

function sum(...) -- variable arguments
  local ret = 0
  for i, v in ipairs{...} do
    ret = ret + v
  end
  return ret
end
sum(2, 3, 4, 5) -- 14


t = {}
function t:func(x, y) -- self syntatic sugar
  self.x = x
  self.y = y
end

t:func(1, 1)
print(t.x) -- 1


-- Arrays
arr = {"sam", "cas", "tro"}
print(arr[1], arr[2], arr[3]) -- indexes start at 1 !!!
print("The array size is: " .. #arr)


-- Tables
x = 5
k = "anokey"
ta = {akey = 2, [k] = 3}
ta[k] = 4
print(ta["akey"], ta[k])
ta.akey = 4 -- syntactic sugar for string keys
print(ta.akey, ta.anokey)


-- Table module
t = {34, 54, 65, 34, 464, 64}
table.insert(t, 50) -- add 50 at the table end
table.insert(t, 3, 89) -- add 89 at the index 3
table.remove(t, 2) -- remove the value at index 2
table.sort(t) -- sorts via less then (<)


-- String
s = "foo\nbar" -- new line
t = 'he said "hello world"'
u = "Hello \"world\"" -- escape double quotes
v = [[
<html>
  <body>
    <p>Hello world!</p>
  </body>
</html>
]] -- multi-line string


-- String module
string.lower("HeLLO") -- hello
string.upper("Hello") -- HELLO
string.reverse("world") -- dlrow
string.char(87) -- W
string.sub("hello world", 2, 5) -- ello


-- Regex strings
string.gsub("hello 42", "(%d+)", "%1 3") -- hello 42 3
string.gsub("heLLo", "(%u)", "") -- heo

string.gsub("2 + 2 = 4", "(%d)", function(s) -- 4 + 4 = 8
  return s * 2
end)

for w in string.gmatch("good morning chaps", "%w+") do -- prints each word
  print(w)
end


-- Numbers
-- variations: 4, 0.4, .4, 4.3, 0xFF, 0xA33FF0E, 8.7e12, 8.7e+12, 8e-12


-- Loading files / modules
func = loadfile("module.lua") -- loads the file into a function
func() -- run the function
x = dofile("module.lua") -- loads and runs the file and stores the return on x


-- Package system
require("cheese") -- takes a path to a Lua file and searches for it
require("folder.subfolder.file") -- require replaces each dot with the directory separator


-- Executing strings
loadstring("print('stuff')")() -- loads and runs the lua code inside the string

## class_example.lua
local Person = {}

function Person:new(fname, lname, age)
   local meta = setmetatable({},self)
   self.__index = self

   self.fname = fname
   self.lname = lname
   self.age   = age

   function Person:fullName()
      return self.fname .. ' ' .. self.lname
   end

   return meta
end
return Person


--[[
Person = require("main")
sam = Person:new("samuel","castro", 30)
print(sam:fullName())
]]

## ref_value.lua
local pval = "old"            -- PASSED BY VAL: nil, boolean, number, string
local pref = {"old1", "old2"} -- PASSED BY REF: function, userdata, thread, table

function valuefunc(a)
   a = "new" -- new var NOT the passed
end

function reffunc(b)
   -- ref to the passed table
   b[1] = "new1"
   b[2] = "new2"
end

valuefunc(pval) -- passing a string by value
reffunc(pref) -- passing a table by ref

print(pval, pref[1],pref[2]) -- old new1 new2
	-- Variables
	v1, v2, v3 = 3, 2, 1
	print(v1,v2,v3, v4 --[[by default it's nil]])

	v5, v6, v7 = true, 1, 0 -- Are all "true" values
	v8, v9 = false, nil -- Are the only "false" values

	--[[ Operators
	1 - The logical AND, OR, and NOT
	2 - The inequality operator is ~= instead of !=.
	3 - .. is the operator for string concatenation.
	4 - ^ raises a number to a power
	5 - # is an operator used to get the length of tables and strings
	]]


	-- Conditionals
	if state == 5 then
	print(state)
	end


	-- Loops
	while x < 10 do
	x = x + 2
	print(x)
	end

	while true do
	print("run once")
	break
	end

	i = 5
	repeat
	i = i - 1
	print(i)
	until i == 1

	for i = 1, 11, 2 do -- for var = start, limit, step do
	x = x * i
	print(x)
	end

	if pcall(function () print(a[i]) end) then -- protected function call
	print("cool")
	else
	print("error")
	end

	error("string expected") -- throw error


	-- Generic for loops
	days = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
	b = { 20, 30, 40 }

	for key, value in pais(days) do
	print(key, value)
	end

	for index, value in ipairs(b) do
	print(index, value)
	end


	-- Functions
	function first(v1, v2)
	local x, y = second(v1 or 1, v2 or 2)
	print(x, y)
	end
	function second(v1, v2)
	return v1+1, v2+1
	end
	first(2, 3)
	first() -- the "or" works as a optional value alternative

	function sum(...) -- variable arguments
	local ret = 0
	for i, v in ipairs{...} do
	ret = ret + v
	end
	return ret
	end
	sum(2, 3, 4, 5) -- 14


	t = {}
	function t:func(x, y) -- self syntatic sugar
	self.x = x
	self.y = y
	end

	t:func(1, 1)
	print(t.x) -- 1


	-- Arrays
	arr = {"sam", "cas", "tro"}
	print(arr[1], arr[2], arr[3]) -- indexes start at 1 !!!
	print("The array size is: " .. #arr)


	-- Tables
	x = 5
	k = "anokey"
	ta = {akey = 2, [k] = 3}
	ta[k] = 4
	print(ta["akey"], ta[k])
	ta.akey = 4 -- syntactic sugar for string keys
	print(ta.akey, ta.anokey)


	-- Table module
	t = {34, 54, 65, 34, 464, 64}
	table.insert(t, 50) -- add 50 at the table end
	table.insert(t, 3, 89) -- add 89 at the index 3
	table.remove(t, 2) -- remove the value at index 2
	table.sort(t) -- sorts via less then (<)


	-- String
	s = "foo\nbar" -- new line
	t = 'he said "hello world"'
	u = "Hello \"world\"" -- escape double quotes
	v = [[
	<html>
	<body>
	<p>Hello world!</p>
	</body>
	</html>
	]] -- multi-line string


	-- String module
	string.lower("HeLLO") -- hello
	string.upper("Hello") -- HELLO
	string.reverse("world") -- dlrow
	string.char(87) -- W
	string.sub("hello world", 2, 5) -- ello


	-- Regex strings
	string.gsub("hello 42", "(%d+)", "%1 3") -- hello 42 3
	string.gsub("heLLo", "(%u)", "") -- heo

	string.gsub("2 + 2 = 4", "(%d)", function(s) -- 4 + 4 = 8
	return s * 2
	end)

	for w in string.gmatch("good morning chaps", "%w+") do -- prints each word
	print(w)
	end


	-- Numbers
	-- variations: 4, 0.4, .4, 4.3, 0xFF, 0xA33FF0E, 8.7e12, 8.7e+12, 8e-12


	-- Loading files / modules
	func = loadfile("module.lua") -- loads the file into a function
	func() -- run the function
	x = dofile("module.lua") -- loads and runs the file and stores the return on x


	-- Package system
	require("cheese") -- takes a path to a Lua file and searches for it
	require("folder.subfolder.file") -- require replaces each dot with the directory separator


	-- Executing strings
	loadstring("print('stuff')")() -- loads and runs the lua code inside the string
	local Person = {}

	function Person:new(fname, lname, age)
	local meta = setmetatable({},self)
	self.__index = self

	self.fname = fname
	self.lname = lname
	self.age = age

	function Person:fullName()
	return self.fname .. ' ' .. self.lname
	end

	return meta
	end
	return Person


	--[[
	Person = require("main")
	sam = Person:new("samuel","castro", 30)
	print(sam:fullName())
	]]
	local pval = "old" -- PASSED BY VAL: nil, boolean, number, string
	local pref = {"old1", "old2"} -- PASSED BY REF: function, userdata, thread, table

	function valuefunc(a)
	a = "new" -- new var NOT the passed
	end

	function reffunc(b)
	-- ref to the passed table
	b[1] = "new1"
	b[2] = "new2"
	end

	valuefunc(pval) -- passing a string by value
	reffunc(pref) -- passing a table by ref

	print(pval, pref[1],pref[2]) -- old new1 new2