Variables, Data Types, and Operators in Lua

What Is a Variable?

A variable is a named container that stores data in memory. You can think of a variable as a labeled box where information is kept so it can be reused later.

In programming, variables allow you to:

• Store values
• Modify values
• Reference values by name
• Build logic and calculations

Without variables, programs would not be able to remember anything.

Variables in Real Life (Analogy)

Imagine writing your name on a piece of paper.

• The name is the variable
• The paper is memory
• The text written is the value

If you erase the text and write something else, the paper (variable) still exists, but the value changes. This is exactly how variables work in Lua.

Creating Variables in Lua

In Lua, variables are created using assignment.

age = 18

This line:

• Creates a variable named age
• Stores the value 18 inside it

Lua automatically decides the data type based on the value.

Dynamic Typing in Lua

Lua is a dynamically typed language.

This means:

• You do not specify data types explicitly
• Variables can change types at runtime

Example:

value = 10
value = "ten"

The same variable now holds a number and then a string. This flexibility is powerful but requires discipline.

Global Variables vs Local Variables

score = 100

-- Using the "local" keyword
local score = 100

Variable Naming Rules

Lua variable names:

• • Can contain letters, numbers, and underscores
• • Must start with a letter or underscore
• • Are case-sensitive

Valid Examples:

playerScore
_playerName
score1

Invalid Examples:

1score       -- Cannot start with a digit
player-score -- Hyphens not allowed
local        -- Reserved keyword

Naming Conventions

Good variable names are descriptive, readable, and meaningful.

Readable code is more important than short code.

Introduction to Data Types

A data type defines what kind of value a variable holds and how Lua treats it.

Lua has a small but powerful set of built-in data types:

In this lesson, we focus on the most commonly used ones.

The nil Type

nil represents the absence of a value.

value = nil

Uses of nil:

• • Indicating missing data
• • Resetting variables
• • Checking if something exists

Accessing an undefined variable returns nil.

The number Type

Lua uses a single type for numbers.

age = 25
price = 19.99

Numbers can represent:

• • Integers
• • Decimals
• • Mathematical results

Lua handles numeric operations internally.

The string Type

Strings represent text data.

name = "Lua"
message = 'Hello, World'

Strings:

• • Are enclosed in quotes
• • Can contain spaces and symbols
• • Are immutable

You will explore strings deeply in a dedicated lesson.

The boolean Type

Booleans represent truth values.

isAlive = true
isGameOver = false

Booleans are used heavily in:

• • Conditions
• • Loops
• • Game logic
• • Decision making

Checking Data Types

You can check a variable"s type using type().

print(type(age))
print(type(name))
print(type(isAlive))

This is useful for debugging and validation.

Common Beginner Mistakes

• Forgetting local
• Reusing variable names carelessly
• Assuming strict typing
• Using unclear variable names

Avoiding these mistakes early builds strong habits.

Practice Task

1. Create five variables of different types
2. Print each variable
3. Print the type of each variable
4. Change one variable's type and print it again

Part 1 Summary

In this part, you learned:

• What variables are
• How Lua handles variables
• Global vs local variables
• Variable naming rules
• Core data types

These concepts are the backbone of every Lua program.