Lua Variables Basics

Now that you have written your first Lua program and learned how to display messages using the print function, it’s time to take the next step. In this lesson, you will discover how to store and use information in your programs using variables. This is a key concept in all programming languages, and it will help you make your Lua scripts much more powerful and flexible.

A variable is like a labeled box where you can store data, such as a word, a number, or even more complex information. In Lua, you can create a variable using the local keyword, give it a name, and assign it a value. For example, if you want to store your travel destination, you can write:

local destination = "Paris"

You can then use the print function to display the value stored in your variable:

print(destination)

When you run this code, Lua will show the word Paris in the output. This is because the variable destination holds the value "Paris", and print(destination) tells Lua to display it.

Output:

Paris

Variable names in Lua are case sensitive. This means that destination, Destination, and DESTINATION are all considered different variables. For example, if you try to print Destination instead of destination, you will not see an error, but Lua will print nil because Destination has not been defined:

local destination = "Paris"
print(Destination)  -- This will print 'nil'

So, always make sure to use the exact same capitalization when referring to your variables, or you might accidentally refer to a variable that doesn't exist and get unexpected results like nil in your output.

In Lua, the name you give to a variable is called an identifier. Identifiers are used to label and refer to your variables throughout your code. There are a few simple rules to follow when creating identifiers in Lua:

• An identifier must start with a letter (a–z or A–Z) or an underscore (_).
• After the first character, you can use letters, numbers (0–9), or underscores.
• Identifiers are case sensitive. For example, score and Score are different variables.
• You cannot use spaces or special characters (like !, @, #, etc.) in identifiers.
• Identifiers cannot be the same as Lua’s reserved keywords (such as local, if, end, etc.).

Here are some examples of valid and invalid identifiers:

local player1 = "Alice"      -- valid
local _score = 100           -- valid
local totalAmount = 50       -- valid
local 2ndPlace = "Bob"       -- invalid: cannot start with a number
local player-name = "Eve"    -- invalid: cannot use hyphens
local end = 10               -- invalid: 'end' is a reserved keyword

Choosing clear and descriptive identifiers makes your code easier to read and understand. For example, use destination instead of just d if you want to store a travel destination.