print("Hello World")
--this is a comment
print("hello") --this is another comment
-- the next line will not do anything because it is commented out
--print("world")
-- Different types
local x = 10 --number
local name = "john doe" --string
local isAlive = false -- boolean
local a = nil --no value or invalid value
Numbers
operators
- + addition
- - minus
- * multiply
- / divide
- ^ power
- % modulus
-- examples
local a = 1
local b = 2
local c = a + b
print(c) -- 3
local d = b - a
print(d) -- 1
local x = 1 * 3 * 4 -- 12
print(x)
local y = (1+3) * 2 -- 8
print(y)
print(10/2) -- 5
print (2^2) -- 4
print(5%2) -- 1
print(-b) -- -2
-- increment
local level = 1
level = level + 1
print(level) -- 2
Strings
-- concatenate strings
local phrase = "My name is "
local name = "John Doe"
print(phase .. name) --My name is John Doe
-- strings and numbers
local age = 12
local name = "Billy"
print(name .. " is " .. age .. " years old")
Boolean
local isAlive = true
print(isAlive) --true
isAlive = false
print(isAlive) --false
--number comparisions
local age = 10
if age < 18 then
print("over 18") --this will not be executed
end
--elseif and else
age = 20
if age > 18 then
print("dog")
elseif age == 18 then
print("cat")
else
print("mouse")
end
Comparison Operators
- == equality
- < less than
- > greater than
- <= less than or equal to
- >= greater than or equal to
- ~= inequality
--boolean comparision
local isAlive = true
if isAlive then
print("dog")
end
--string comparisions
local name = "billy"
if name == "Billy" then --false
print("Billy")
elseif name == "billy" then --true
print("billy")
end
Combining Statements
local x = 10
if x == 10 and x < 0 then --both are true
print("dog")
elseif x == 100 or x < 0 then --1 or more are true
print("cat")
end
--result: cat
Nested statements
local x = 10
local isAlive = true
if x==10 then
if isAlive == true then
print("dog")
else
print("cat")
end
end
Invert Value
you can also invert a value with the not keyword
local x = 10
if not x == 10 then
print("here")
end
function printTax(price)
local tax = price * 0.21
print("tax:" .. tax)
end
printTax(200)
--function that returns a value
function calculateTax(price)
return price * 0.21
end
local result = calculateTax(100)
print(result)
--reusing the function but this time using variables
local bread = 130
local milk = 110
local breadTax = calculateTax(bread) --27.3
local milkTax = calculateTax(milk) --23.1
print("Bread Tax = " .. breadTax)
print("Milk Tax = " .. milkTax)
--multiple parameters
function displayInfo(name, age, country)
print(name .. " is " .. age .. " years old and is from " .. country)
end
displayInfo("Billy", 12, "Jupiter")
Variables have different scopes. Once the end of the scope is reached the values in that scope are no longer accessable
function foo()
local a = 10
end
print(a) --nil
local isAlive = true
if isAlive then
local a = 10
end
print(a) --nil
Global Variable
local _G.myValue = 69
--doing this can sometimes be bad practice
There is a few different ways you can do a loop in lua
--while loop
local i = 0
local count = 0
while i <= 10 do
count = count + 1
end
print("count is " .. count) --count is 7
--for loop
count = 0
for i=1, 5 do
count = count + 1
end
print("count is " .. count)
Infinite Loops
--infinite loop will never end
local i = 0
while i >= 0 do
i = i + 1
print(i)
end
Nested Loops
local count = 0
for a=1, 10 do
for b=1, 10 do
count = count + 1
end
end
print(count) -- 100
--basic table
local colors = { "red", "green", "blue" }
print(colors[1]) --red
print(colors[2]) --green
print(colors[3]) --blue
--using a loop to iterate though your table
for i=1, #colors do
print(colors[i])
end
Table Manipulation
--insert
local colors = { "red", "green", "blue" }
table.insert(colors, "orange")
local index = #colors --4 (this is the last index in the table)
print(colors[index]) --orange
--insert at index
local colors = { "red", "green", "blue" }
table.insert(colors, 2, "pink")
for i=1, #colors do
print(colors[i])
end
--red, pink, green, blue
--remove
local colors = { "red", "green", "blue" }
table.remove(colors, 1)
for i=1, #colors do
print(colors[i])
end
-- "green", "blue"
2 Dimensional Table
--tables within tables
local data = {
{ "billy", 12 },
{ "john", 20 },
{ "andy", 65 }
}
for a=1, #data do
print(data[a][1] .. " is " .. data[a][2] .. " years old")
end
Key Tables
2 dimensional tables are not suited to data with different types, instead uses keys for tables
local teams = {
["teamA"] = 12,
["teamB"] = 15
}
print(teams["teamA"]) -- 12
for key,value in pairs(teams) do
print(key .. ":" .. value)
end
--insert into key table
teams["teamC"] = 1
--remove key from table
teams["teamA"] = nil
Returning a Table from a Function
This can be used to return multiple values from a functions
function getTeamScores()
local scores = {
["teamA"] = 12,
["teamB"] = 15
}
return scores
end
local scores = getTeamScores()
local total = 0
for key, val in pairs(scores) do
total += val
end
print("Total score of all teams:" .. total)
The math class has a number of functions for dealing with numbers. You may not need them but here is some of the more useful one functions:
More: Wiki
- abs (absolute value)
local x = -10 print(math.abs(x)) --result: 10 local a = 10 print(math.abs(a)) --result: 10
- ceil (round up decimal value)
local x = 1.2 print(math.ceil(x)) --result: 2
- deg (Convert value from radians to degrees)
print(math.deg(math.pi)) -- result: 180
- floor (round down decimal value)
local x = 1.2 print(math.floor(x)) --result: 1
- pi (constant value of pi)
print(math.pi) --3.1415926535898 3.1415926535898
- rad (Convert value from degrees to radians)
print(math.rad(180)) --result: 3.1415926535898
- random (random number generation)
--random value between 0 tand 1 print(math.random()) --result: 0.0012512588885159 --random integer value from 1 to 100 (both inclusive) print(math.random(100)) --result: 20 --random integer value from 20 to 100 (both inclusive) print(math.random(20, 100)) --result: 54
- sqrt (Square root of a number)
print(math.sqrt(100)) --result: 10
Include code other files
require("otherfile")