Loops

5 min

A loop lets you execute code multiple times. Each type of Lua loop repeats a block of code but in different ways.

Loop Types

for — do

The for—do loop lets you run a command or group of commands a set number of times. The basic syntax includes a control variable, a start value, an end value, and an optional increment value.

for

count

control
variable

=

1

start

,

10

end

,

1

increment

do

Beginning with the start value, the loop will count up or down each time it runs the code between do and end until it reaches the end value. For example, the following loop starts at 1 and counts up until 5, printing the value of count (the control variable) on each iteration:

				
					Code Sample
				
					Expected Output
				
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			for count = 1, 5 do
	print(count)
end
		
			1
2
3
4
5
		
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If an increment is included in the statement, a positive value will count up while a negative value will count down:

				
					Code Sample
				
					Expected Output
				
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			for count = 1, 10, 2 do
	print(count)
end
		
			1
3
5
7
9
		
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					Code Sample
				
					Expected Output
				
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			for count = 3, 0, -0.5 do
	print(count)
end
		
			3
2.5
2
1.5
1
0.5
0
		
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while — do

The while—do loop evaluates if a condition is true or false. If false, the loop ends and the code following it continues to execute. If true, the code between do and end executes and the true/false condition is reevaluated afterward.

				
					Code Sample
				
					Expected Output
				
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			local timeRemaining = 10

while timeRemaining > 0 do
	print("Seconds remaining: " .. timeRemaining)
	wait(1)
	timeRemaining = timeRemaining - 1	
end

print("Timer reached zero!")
		
			Seconds remaining: 10
Seconds remaining: 9
Seconds remaining: 8
Seconds remaining: 7
Seconds remaining: 6
Seconds remaining: 5
Seconds remaining: 4
Seconds remaining: 3
Seconds remaining: 2
Seconds remaining: 1
Timer reached zero!
		
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The while—do loop can also be used for infinite game loops by using simply true as the condition:

				
					Expected Output
				
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			while true do
	print("Looping...")
	wait(0.5)
end
		
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Always include a delay such as wait() inside an infinite loop, as omitting it can freeze the game.

repeat — until

A repeat—until loop repeats until a certain condition is met. Note that the code between repeat and until is executed at least once because the conditional test is performed afterward.

				
					Code Sample
				
					Expected Output
				
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			local currentGoblinCount = 18

-- Spawn goblins up to a maximum of 25 in the game
repeat
	spawnGoblin()
	currentGoblinCount = currentGoblinCount + 1
	print("Current goblin count: " .. currentGoblinCount)
until currentGoblinCount == 25

print("Goblins repopulated!")
		
			Current goblin count: 19
Current goblin count: 20
Current goblin count: 21
Current goblin count: 22
Current goblin count: 23
Current goblin count: 24
Current goblin count: 25
Goblins repopulated!
		
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Breaking Loops

If you’re running a loop that won’t typically end, such as an infinite while—do loop, you can force it to end with the break command so the script can continue running the code following it:

				
					Code Sample
				
					Expected Output
				
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			local secondsElapsed = 0
local timeout = 5

while true do
	print("Looping...")
	wait(1)
	secondsElapsed = secondsElapsed + 1

	if secondsElapsed == timeout then
		break
	end
end

print("Loop ended; moving on!")
		
			Looping...
Looping...
Looping...
Looping...
Looping...
Loop ended; moving on!
		
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Tags:

coding
lua
loop
repeat

Loops

Loops

Loop Types

for — do

while — do

repeat — until

Breaking Loops

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