Lua Guard
Your comprehensive platform for learning and developing with Lua and Luau
Interactive Documentation
Learn Lua and Luau with comprehensive guides, syntax references, and best practices.
Developer Tools
Professional tools for Lua development including obfuscators, formatters, and analyzers.
Practical Examples
Explore real-world coding examples and learn from practical implementations.
Real-time Processing
Process your Lua code instantly with our integrated development tools.
Introduction to Lua
Lua is a powerful, efficient, lightweight, embeddable scripting language. It supports procedural programming, object-oriented programming, functional programming, data-driven programming, and data description.
What is Lua?
Lua is designed, implemented, and maintained by a team at PUC-Rio, the Pontifical Catholic University of Rio de Janeiro in Brazil. Lua was born and raised in academia but has gradually moved toward industrial applications.
Key Features
- Lightweight: Small memory footprint
- Fast: Excellent performance for a scripting language
- Portable: Runs on virtually any platform
- Embeddable: Easy to integrate with other languages
- Simple: Clean syntax and powerful semantics
Hello World
print("Hello, World!")
Basic Syntax
Lua has a simple and clean syntax. Here are the fundamental elements:
Comments
-- This is a single-line comment
--[[
This is a
multi-line comment
--]]
Statements
Statements in Lua don't need semicolons, but you can use them optionally:
print("Hello")
print("World"); print("!") -- Multiple statements on one line
Case Sensitivity
Lua is case-sensitive. print and Print are different identifiers.
Keywords
Lua has the following reserved keywords:
and break do else elseif end
false for function goto if in
local nil not or repeat return
then true until while
Variables & Types
Variable Declaration
Variables in Lua are global by default. Use local for local variables:
-- Global variables
name = "Alice"
age = 25
-- Local variables
local city = "New York"
local temperature = 72.5
Data Types
Lua has eight basic types:
-- nil
local nothing = nil
-- boolean
local isTrue = true
local isFalse = false
-- number
local integer = 42
local float = 3.14
-- string
local text = "Hello, Lua!"
local multiline = [[
This is a
multiline string
]]
-- function
local function greet()
return "Hello!"
end
-- userdata (C data)
-- thread (coroutines)
-- table
local array = {1, 2, 3, 4, 5}
local object = {name = "John", age = 30}
Type Checking
local value = 42
print(type(value)) -- "number"
value = "Hello"
print(type(value)) -- "string"
Functions
Function Declaration
-- Basic function
function sayHello(name)
print("Hello, " .. name .. "!")
end
-- Local function
local function add(a, b)
return a + b
end
-- Anonymous function
local multiply = function(a, b)
return a * b
end
Multiple Return Values
function getCoordinates()
return 10, 20
end
local x, y = getCoordinates()
print(x, y) -- 10 20
Variable Arguments
function sum(...)
local args = {...}
local total = 0
for i = 1, #args do
total = total + args[i]
end
return total
end
print(sum(1, 2, 3, 4, 5)) -- 15
Closures
function createCounter()
local count = 0
return function()
count = count + 1
return count
end
end
local counter = createCounter()
print(counter()) -- 1
print(counter()) -- 2
Tables
Tables are Lua's only data structuring mechanism. They can represent arrays, sets, records, graphs, trees, etc.
Array-like Tables
-- Array (1-indexed)
local fruits = {"apple", "banana", "orange"}
print(fruits[1]) -- "apple"
print(#fruits) -- 3 (length)
Dictionary-like Tables
-- Dictionary/Hash table
local person = {
name = "Alice",
age = 30,
city = "Boston"
}
print(person.name) -- "Alice"
print(person["age"]) -- 30
Mixed Tables
local mixed = {
"first", -- [1]
"second", -- [2]
name = "Mixed", -- ["name"]
count = 100 -- ["count"]
}
print(mixed[1]) -- "first"
print(mixed.name) -- "Mixed"
Table Operations
local t = {}
t.x = 10 -- Add field
t["y"] = 20 -- Add field
table.insert(t, "end") -- Add to end
table.remove(t, 1) -- Remove by index
-- Iterate over table
for key, value in pairs(t) do
print(key, value)
end
Control Flow
Conditional Statements
-- if-then-else
local age = 18
if age >= 18 then
print("Adult")
elseif age >= 13 then
print("Teenager")
else
print("Child")
end
Loops
-- while loop
local i = 1
while i <= 5 do
print(i)
i = i + 1
end
-- repeat-until loop
local j = 1
repeat
print(j)
j = j + 1
until j > 5
-- for loop (numeric)
for k = 1, 5 do
print(k)
end
-- for loop with step
for m = 1, 10, 2 do
print(m) -- 1, 3, 5, 7, 9
end
-- for loop (generic)
local fruits = {"apple", "banana", "orange"}
for index, fruit in ipairs(fruits) do
print(index, fruit)
end
Break and Return
for i = 1, 10 do
if i == 5 then
break -- Exit loop
end
print(i)
end
function findValue(table, target)
for i, value in ipairs(table) do
if value == target then
return i -- Exit function early
end
end
return nil
end
Strings
String Creation
local str1 = "Hello"
local str2 = 'World'
local str3 = [[Multi-line
string content]]
String Concatenation
local greeting = "Hello" .. " " .. "World"
print(greeting) -- "Hello World"
String Length
local text = "Lua programming"
print(#text) -- 15
print(string.len(text)) -- 15
String Functions
local text = "Hello, Lua!"
-- Convert case
print(string.upper(text)) -- "HELLO, LUA!"
print(string.lower(text)) -- "hello, lua!"
-- Substring
print(string.sub(text, 1, 5)) -- "Hello"
-- Find pattern
local pos = string.find(text, "Lua")
print(pos) -- 8
-- Replace
local newText = string.gsub(text, "Lua", "World")
print(newText) -- "Hello, World!"
String Formatting
local name = "Alice"
local age = 25
local formatted = string.format("Name: %s, Age: %d", name, age)
print(formatted) -- "Name: Alice, Age: 25"
Modules
Creating Modules
-- math_utils.lua
local M = {}
function M.add(a, b)
return a + b
end
function M.multiply(a, b)
return a * b
end
M.PI = 3.14159
return M
Using Modules
-- main.lua
local math_utils = require("math_utils")
print(math_utils.add(5, 3)) -- 8
print(math_utils.multiply(4, 7)) -- 28
print(math_utils.PI) -- 3.14159
Global vs Local Modules
-- Global approach (not recommended)
math_utils = {}
function math_utils.add(a, b)
return a + b
end
-- Local approach (recommended)
local math_utils = {}
local function add(a, b)
return a + b
end
math_utils.add = add
return math_utils
Luau Features
Luau is Roblox's version of Lua with additional features and optimizations.
Type Annotations
-- Function with type annotations
local function add(a: number, b: number): number
return a + b
end
-- Variable type annotations
local name: string = "Alice"
local age: number = 25
local isStudent: boolean = true
String Interpolation
local name = "World"
local greeting = `Hello, {name}!`
print(greeting) -- "Hello, World!"
local x, y = 10, 20
local coords = `Position: ({x}, {y})`
print(coords) -- "Position: (10, 20)"
Generics
-- Generic function
local function identity(value: T): T
return value
end
local numberResult = identity(42) -- number
local stringResult = identity("hello") -- string
Improved typeof
local value = 42
print(typeof(value)) -- "number" (more precise than type())
local instance = Instance.new("Part")
print(typeof(instance)) -- "Instance"
Continue Statement
for i = 1, 10 do
if i % 2 == 0 then
continue -- Skip even numbers
end
print(i) -- Only prints odd numbers
end
Compound Assignment
local x = 10
x += 5 -- equivalent to x = x + 5
x -= 3 -- equivalent to x = x - 3
x *= 2 -- equivalent to x = x * 2
x /= 4 -- equivalent to x = x / 4
Lua Quiz
Test your knowledge of Lua with this interactive quiz. Select the correct answer for each question.
What is the correct way to declare a local variable in Lua?
What is the output of: print(#{"apple", "banana", "orange"})?
Which operator is used for string concatenation in Lua?
Lua Development Tools
Lua Obfuscator
Obfuscate your Lua code to protect it from reverse engineering and unauthorized access.
Code Formatter
Format and beautify your Lua code with proper indentation, spacing, and structure for better readability.
Code Minifier
Minimize your Lua code by removing unnecessary whitespace, comments, and shortening variable names to reduce file size.
Syntax Validator
Check your Lua code for syntax errors, common mistakes, and potential issues before running it.
Code Analyzer
Analyze your Lua code for complexity, performance issues, and coding standards compliance.
Base64 Decoder
Decode Base64 encoded Lua scripts and strings back to readable format.
Debug Helper
Add debug statements and logging to your Lua code to help with troubleshooting and development.
Lua Playground
Execute Lua code directly in your browser with a live interactive environment.
JSON to Lua Converter
Convert JSON data structures to equivalent Lua table format.
Bytecode Viewer
View and analyze the bytecode generated from your Lua source code.
Lua to Luau Converter
Convert standard Lua code to Luau (Roblox) syntax with type annotations.
Snippet Generator
Generate reusable code snippets for common Lua programming patterns.
Lua Obfuscator - Input Code
Obfuscated Output
Obfuscated code will appear here...
Code Formatter - Input Code
Formatted Output
Formatted code will appear here...
Code Minifier - Input Code
Minified Output
Minified code will appear here...
Syntax Validator - Input Code
Validation Results
Validation results will appear here...
Code Analyzer - Input Code
Analysis Results
Code analysis results will appear here...
Base64 Decoder - Input
Decoded Output
Decoded content will appear here...
Debug Helper - Input Code
Debug-Enhanced Code
Code with debug statements will appear here...
Lua Playground
Output will appear here...
Playground Information
About the Lua Playground
The Lua Playground allows you to execute Lua code directly in your browser. This is a great way to experiment with Lua syntax and test small code snippets.
Features:
- Real-time code execution
- Syntax highlighting
- Error reporting
- Output display
Limitations:
- No file I/O operations
- No network access
- Limited standard library
- Execution timeout for safety
Example Code:
-- Simple function
function greet(name)
return "Hello, " .. name .. "!"
end
-- Call the function
print(greet("World"))
-- Loop example
for i = 1, 5 do
print("Count: " .. i)
end
JSON to Lua Converter - Input JSON
Lua Table Output
Lua table will appear here...
Bytecode Viewer - Input Code
Bytecode Output
Bytecode will appear here...
Lua to Luau Converter - Input Code
Luau Output
Luau code will appear here...
Snippet Generator
Generated Snippet
Select a snippet type and click Generate...
Lua Code Examples
Hello World
A simple introduction to Lua programming.
print("Hello, World!")
print("Welcome to Lua programming!")
Variables and Types
Working with different data types in Lua.
local name = "Alice"
local age = 25
local height = 5.6
local isStudent = true
print("Name:", name, "Type:", type(name))
print("Age:", age, "Type:", type(age))
print("Height:", height, "Type:", type(height))
print("Student:", isStudent, "Type:", type(isStudent))
Functions
Creating and using functions with parameters and return values.
function add(a, b)
return a + b
end
local function factorial(n)
if n <= 1 then
return 1
else
return n * factorial(n - 1)
end
end
print("5 + 3 =", add(5, 3))
print("5! =", factorial(5))
Tables and Arrays
Working with Lua's versatile table data structure.
-- Array-like table
local fruits = {"apple", "banana", "orange", "grape"}
print("Fruits:")
for i = 1, #fruits do
print(i .. ":", fruits[i])
end
-- Dictionary-like table
local person = {
name = "John",
age = 30,
city = "New York"
}
print("\nPerson info:")
for key, value in pairs(person) do
print(key .. ":", value)
end
Error-Prone Code
Code with syntax errors for testing the validator.
function broken_function()
print("Missing closing parenthesis"
if true then
print("Missing end statement"
local x = 5 +
return x
end
Base64 Example
Base64 encoded Lua script for decoding.
bG9jYWwgZnVuY3Rpb24gc2F5SGVsbG8obmFtZSkKICAgIHByaW50KCJIZWxsbywgIiAuLiBuYW1lIC4uICIhIikKZW5kCgpzYXlIZWxsbygid29ybGQiKQ==
Complex Algorithm
A complex function that would benefit from debug statements.
local function quicksort(arr, low, high)
if low < high then
local pi = partition(arr, low, high)
quicksort(arr, low, pi - 1)
quicksort(arr, pi + 1, high)
end
end
local function partition(arr, low, high)
local pivot = arr[high]
local i = low - 1
for j = low, high - 1 do
if arr[j] <= pivot then
i = i + 1
arr[i], arr[j] = arr[j], arr[i]
end
end
arr[i + 1], arr[high] = arr[high], arr[i + 1]
return i + 1
end
Module Example
Creating and using a simple module.
-- mymodule.lua
local M = {}
function M.greet(name)
return "Hello, " .. name .. "!"
end
function M.calculate(a, b)
return a + b, a * b
end
return M
-- main.lua
local mymodule = require("mymodule")
print(mymodule.greet("Alice"))
local sum, product = mymodule.calculate(5, 3)
print("Sum:", sum, "Product:", product)
Playground Example
Try this example in the Lua Playground.
-- Calculate factorial
function factorial(n)
if n <= 1 then
return 1
else
return n * factorial(n - 1)
end
end
-- Test the function
for i = 1, 10 do
print(i .. "! =", factorial(i))
end
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