Lua - Operators

Hello, budding programmers! Today, we're going to embark on an exciting journey into the world of Lua operators. Don't worry if you've never coded before – I'll be your friendly guide, and we'll explore this topic step by step. By the end of this lesson, you'll be manipulating data like a pro!

Arithmetic Operators

Let's start with something familiar: math! Lua provides us with arithmetic operators that work just like the ones you've used in math class.

Basic Arithmetic Operators

Here's a table of the basic arithmetic operators in Lua:

Operator	Description	Example
+	Addition	5 + 3 = 8
-	Subtraction	10 - 4 = 6
*	Multiplication	3 * 4 = 12
/	Division	20 / 5 = 4
%	Modulus (remainder)	17 % 5 = 2
^	Exponentiation	2 ^ 3 = 8

Let's see these in action:

print(5 + 3)  -- Output: 8
print(10 - 4) -- Output: 6
print(3 * 4)  -- Output: 12
print(20 / 5) -- Output: 4
print(17 % 5) -- Output: 2
print(2 ^ 3)  -- Output: 8

Each line performs a different arithmetic operation and prints the result. The -- symbol indicates a comment, which is ignored by Lua but helps us understand the code.

The Modulus Operator

The modulus operator (%) might be new to some of you. It gives us the remainder after division. Think of it as asking, "If I divide these numbers, what's left over?" For example, when we divide 17 by 5, we get 3 with a remainder of 2. That's why 17 % 5 equals 2.

Relational Operators

Now, let's move on to relational operators. These are used to compare values and always result in either true or false.

Operator	Description	Example
==	Equal to	5 == 5 is true
~=	Not equal to	5 ~= 4 is true
>	Greater than	7 > 3 is true
<	Less than	2 < 8 is true
>=	Greater than or equal to	5 >= 5 is true
<=	Less than or equal to	4 <= 4 is true

Let's try these out:

print(5 == 5)  -- Output: true
print(5 ~= 4)  -- Output: true
print(7 > 3)   -- Output: true
print(2 < 8)   -- Output: true
print(5 >= 5)  -- Output: true
print(4 <= 4)  -- Output: true

Remember, in Lua, we use ~= for "not equal to", which is different from some other programming languages that use !=.

Logical Operators

Logical operators are used to combine conditional statements. They're like the "and", "or", and "not" in everyday language.

Operator	Description
and	True if both operands are true
or	True if at least one operand is true
not	Reverses the logical state

Here's how we use them:

print(true and false)  -- Output: false
print(true or false)   -- Output: true
print(not true)        -- Output: false

-- We can use these with variables too
local x = 5
local y = 10
print(x < 10 and y > 5)  -- Output: true
print(x > 10 or y < 5)   -- Output: false

In the last example, x < 10 and y > 5 is true because both conditions are true: x is less than 10, and y is greater than 5.

Misc Operators

Lua has a couple of other operators that don't fit neatly into the previous categories:

Operator	Description	Example
..	Concatenation (joining strings)	"Hello " .. "World" = "Hello World"
#	Length operator	#"Hello" = 5

Let's see these in action:

print("Hello " .. "World")  -- Output: Hello World
print(#"Hello")             -- Output: 5

The concatenation operator (..) is super useful when you want to combine strings. The length operator (#) tells you how many characters are in a string.

Operators Precedence in Lua

Just like in math, Lua has an order of operations. Here's the precedence from highest to lowest:

1. ^
2. not # - (unary)
3. • /
5. ..
6. < > <= >= ~= ==
7. and
8. or

This means that in an expression like 2 + 3 * 4, Lua will first do the multiplication (3 * 4 = 12) and then the addition (2 + 12 = 14).

If you want to change the order, you can use parentheses. For example:

print(2 + 3 * 4)     -- Output: 14
print((2 + 3) * 4)   -- Output: 20

In the second line, the parentheses tell Lua to do the addition first, then multiply the result by 4.

And there you have it! You've just taken your first steps into the world of Lua operators. Remember, practice makes perfect. Try combining these operators in different ways and see what happens. Don't be afraid to make mistakes – that's how we learn!

In my years of teaching, I've found that the best programmers are the ones who aren't afraid to experiment. So go ahead, play around with these operators, and see what you can create. Who knows? You might just be the next great Lua programmer!

Credits: Image by storyset