Variables

A variable gives a name to a value so you can use it later.

local name = "iFair"
lh.drawln(name) -- Output: iFair
lh.drawln("name") -- Output: name

Use quotes for text values, but not for variable names.

Declaring and changing variables

Use local to create a variable. To change its value later, use = without another local:

local fps = 60
fps = 120
lh.drawln(fps) -- Output: 120

fps = fps + 10
lh.drawln(fps) -- Output: 130

The right side is calculated before the value is assigned. Lua does not have += or ++.

Names can contain letters, digits, and underscores, but cannot start with a digit or be a keyword such as end. Names like playerName or player_name are fine.

Types

Values have types. Here are the six you will usually work with:

Type	Meaning	Example
number	A number, including decimals	10, 2.5
string	Text inside single or double quotes	"LuaHUD", 'Hello'
boolean	True or false	true, false
nil	No value	nil
function	Code you can call	lh.drawln
table	A group of values	{ "FPS", "Position" }

Lua also has userdata and thread types. You do not need them for these lessons.

Use type(value) to check a type:

local value = 10
lh.drawln(type(value)) -- Output: number

value = "Hello"
lh.drawln(type(value)) -- Output: string

A variable can hold values of different types, though keeping its purpose consistent makes code easier to read.

Missing values

A local variable without a value starts as nil. Reading an undefined global also gives nil.

local name
lh.drawln(type(name)) -- Output: nil

name = "iFair"
name = nil -- Remove the value again.

nil, 0, and the string "nil" are different values.

Local and global variables

A local variable is available from its declaration to the end of its block. A block can be a function, loop, or if branch. At the top of a file, it lasts until the end of that file.

local name = "iFair"

if true then
    local message = "Hello, " .. name
    lh.drawln(message)
end

-- message is no longer available here.

Assigning to a name without local changes an existing variable if one is in scope. Otherwise, it creates or changes a global. Prefer local for your own variables to avoid accidentally sharing or overwriting names.