Chapter 2 - Variables

What is a + b?

Well it could be anything. That's because "a" and "b" don't have a value. Let's change that.

a = 5
b = 3

Let's take another look, what is a + b? What we're really asking is "What is the value of a + the value of b?". In other words, what is 5 + 3? Which is 8.

To proof that a + b = 8, we're going to print it.

a = 5
b = 3
print(a + b)
--Output: 8

Run your code, and your console should say 8 .

a and b are what we call variables. A variable is a word in which you can store a value. The number 4 is always 4, and 35 is always 35, but a variable can be anything you want it to be. Hence the name variable.

The word in which you store a value can be almost anything.

sheep = 3
test = 20
PANTS = 1040
asdfghjkl = 42

Variables are case-sensitive. That means that when you have the same word, but with different casing, it's not treated as the same. For example

sheep = 3
SHEEP = 10
sHeEp = 200

are 3 different variables, with each their own value.

You can do more than just summing up numbers.

a = 20 - 10 --Substraction
b = 20 * 10 --Multiplication
c = 20 / 10 --Division
d = 20 ^ 10 --Exponentiation

For numbers with decimals we use a dot.

a = 10.4
b = 2.63
c = 0.1
pi = 3.141592

Take a look at the following code:

a = 5
b = 3
c = a + b

First we say a = 5. When we give a variable a value, we call that an assignment. We assign 5 to a, and 3 to b. Next we assign a + b to c. So now c equals 8. Remember that you can always check the value of a variable with print. If we were to change the value of a or b after c = a + b, it would not affect c. It would still be 8.

a = 5
b = 3
c = a + b
a = 2
b = 40
print(c)
--Output: 8

This is because in the computer's eyes c is not a + b, it's simply 8.


Strings

A variable can also store text.

text = "Hello World!"

This is what we call a string. Because it's a string of characters.

We can connect strings by using 2 dots (..)

name = "Daniel"
age = "22"
text = "Hello, my name is " .. name .. ", and I'm " .. age .. " years old."
print(text)
--Output: "Hello, my name is Daniel, and I'm 22 years old."

Variable naming rules

There are a few rules when naming a variable. First of all, your variable may have a number in it, but not at the start.

test8 --Good
te8st --Good
8test --Bad, error!

Your variable name also can't include any special characters like @#$%^&*.

And finally, your variable name can't be a keyword. A keyword is a word that the programming language uses. Here's a list of keywords:

and       break     do        else      elseif
end       false     for       function  if
in        local     nil       not       or
repeat    return    then      true      until     while

TL;DR (Too long; Didn't read)

Variables are words in which we can store a value like a number or text. You can name them whatever you want, with a few exceptions. Variables are case-sensitive.