If Statements?⚓︎

If statements offer you a way to only run a certain piece of code if a certain condition holds true. They are a very important part of programming.

You might have a door in your game that only players that are level 20 or above should be able to pass, you would use an if statement to check if the player's level is greater than or equal to 20 and only then open it.

How to use if statements?⚓︎

Let's look at some examples.

if true then
    print("It's true!")
end

What do you think this piece of code would do?

if false then
    print("It's true.")
end

We can also do the same thing with variables:

local myVariable = true

if myVariable then
    print("It holds true.")
end

local myVariable = false

if myVariable then
    print("It holds true!")
end

What if we set myVariable to nil? How does if nil then behave? You can check and you will notice that it behaves just like if false then.

Exercises⚓︎

1. Create a variable that holds any number and create an if statement that checks if this variable holds true and if so, print "Yes. Numbers are treated like true.".

The solutions are on the bottom of this tutorial.

Operators⚓︎

There are some operators you can use in the condition to make if statements even more useful.

== means equal to ~= means not equal to > means greater than < means less than >= means greater than or equal to <= means less than or equal to not means the following condition doesn't hold true

if 5 == 5 then
    print("It's true!")
end

if 5 * 6 <= 12 then
    print("It's true")
end

if true == true then
    print("It's true")
end

Common mistake⚓︎

A common mistake that you should avoid is using = instead of ==.

if true = true then

end

The operator not⚓︎

not basically takes the opposite, so not false would be true and not true would be false. not nil would be true.

Exercises:⚓︎

1. Using an if statement, print "3" if 3 to the power of 10 is greater than 5 to the power of 6.
2. Simplify not (true == true)
3. Simplify not not true
4. Simplify not (not (true == false))

The solutions are on the bottom of this article.

elseif and else⚓︎

Let's say you want to print "Yes" if a variable holds true and "No" if a variable holds false. With what we have learned previously, we could do

local myVariable = true

if myVariable then
    print("Yes")
end

if myVariable == false then
    print("No")
end

local myVariable = true

if myVariable then
    print("Yes")
elseif myVariable == false then
    print("No")
end

Why is this better than our first code⚓︎

Well that's because it's more efficient. Let's say myVariable is true, now in our first code, it will perform two checks, first it will check if it's true and print "Yes" and then it will check if it's false.

Now in our second code, it will check if myVariable is true and print "Yes". There won't be any further checks, so we turned 2 checks into one check.

But if myVariable was false, it would still perform two checks, first checking if it's true and then checking if it's false. We don't really need to check if it's false after we've checked if it's true, because if it's not true then it must be false. This is what else does.

local myVariable = false

if myVariable then
    print("Yes")
else
    print("No")
end

When we were asked why the code where we used elseif or else is better than the code where we just straight forwardly used if, we said it's more efficient. You should know that the difference in performance between the two in normal use is not noticeable though and we really just do it because of the convention and readability.

Exercises⚓︎

1. Check if 7^5 is greater or equal to 5^7, if it is, print "Yes", if not, print "No" using an if and an else statement.
2. Check if nil is equal to false, if it is, print "Yes", if not, print "No" using an if and an elseif statement.

The solutions are on the bottom of this article.

Checking if an object exists⚓︎

If statements are also often used to check if an object exists. You can use objects in the condition and they will be treated as true.

if workspace.Baseplate then
    print("True")
end

But if Baseplate didn't exist, this would error with the errormessage "Attempt to index nil with Baseplate".

So how can we safely check if an object exists or not, if we just use . like in the example above, it will error if it doesn't? => We can use :FindFirstChild().

Using FindFirstChild in the condition⚓︎

FindFirstChild will return the object if it exists and nil if it doesn't. As we know from what we've learned previously, nil in the condition will be treated like false, so this is a safe way of checking if an object exists or not.

So if we are not sure whether the baseplate exists or not, we could use

if workspace:FindFirstChild("Baseplate") then
    print("The baseplate exists!")
else
    print("The baseplate doesn't exist!")
end

Logical Operators⚓︎

Using logical operators, you can often shorten code that uses if statements by a lot. The two logical operators are or and and.

How to use or⚓︎

condition1 or condition2 checks if either is true (or both). For example, false or true would hold true, true or true would also hold true, but false or false would hold false, since both aren't true.

Both are treated as true => selects first⚓︎

If both of the conditions are treated as true, it will select the first, for example 1 or 2 would be 1, right away selecting 1 after seeing that it holds true.

Both are treated as false => selects last⚓︎

If both of the conditions are treated as false, it will select the last, for example nil or false would be false but false or nil would be nil.

How to use and⚓︎

condition1 and condition2 checks if both condition1 and condition2 are true. For example, false and true would be false, false and false would be false but true and true would be true.

Both are treated as true => selects last⚓︎

If both of the conditions are treated as true, it will select the last, for example 3 and 4 would be 4.

Both are treated as false => selects first⚓︎

If both of the conditions are treated as false, it will select the first, for example nil and false would be nil, but false and nil would be false.

Using Logical Operators⚓︎

Let's say we have a variable and we want to check if it's 3 or 5. Here is how we would do that:

local myVariable = 3

if myVariable == 3 or myVariable == 5 then
    print("True")
end

Common mistake⚓︎

A common mistake is using if myVariable == 3 or 5 here. While reading this aloud might make it sound fine, it will be the same as just if myVariable == 3, as we've learned from "Both are treated as true => selects first". You need to include myVariable == for each condition to actually make it a check if it's either 3 or 5, like we did above.

Exercises⚓︎

1. Simplify (true and false) or (false and true)
2. Make a variable that holds "Admin". Then, check if that variable is either "Admin" or "Mod" and if so, print "True."
3. Using logical operators, make a variable hold the number 1 if Baseplate exists in workspace and 2 if not.

The solutions are on the bottom of this article.

Conclusion⚓︎

Thanks for reading. If you find any mistakes, you can report them.

Solutions⚓︎

How to use if statements?⚓︎

1.

local number = 5

if number then
    print("Yes. Numbers are treated like true.")
end

Operators⚓︎

2.

if 3^10 > 5^6 then
    print("3")
end

1. not (true == true) ==> not true ==> false

2. not not true ==> not false ==> true

3. not (not (true == false)) = not (not (false)) = not (true) = false

elseif and else⚓︎

1.

if 7^5 >= 5^7 then
    print("Yes")
else
    print("No")
end

2.

if nil == false then
    print("Yes")
elseif nil ~= false then
    print("No")
end

Logical Operators⚓︎

1. (true and false) or (false and true) ==> false or false ==> false

2. local myVariable = "Admin"
   
   if myVariable == "Admin" or myVariable == "Mod" then
       print("True.")
   end
   

3. local myVariable = workspace:FindFirstChild("Baseplate") and 1 or 2
   

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