Scripting
Loops
Loops allow you to repeat a block of code multiple times based on a specific condition. Below you will find the different types of loops in Lua and how they are used in the Peakboard Designer.
while loop
The while loop executes a block of code as long as a specific condition is met. The syntax for the while loop is as follows:
while condition do
-- code block to be executed while the condition is true
end
Example:
local counter = 1
while counter <= 5 do
print("Counter value: " .. counter)
counter = counter + 1
end
In this example, the loop will be executed as long as the variable counter is less than or equal to 5. The output will be:
Counter value: 1
Counter value: 2
Counter value: 3
Counter value: 4
Counter value: 5
repeat...until loop
The repeat...until loop is similar to the while loop, but evaluates the condition after the code block has been executed. This ensures that the code block is executed at least once regardless of the initial condition. The syntax is as follows:
repeat
-- code block to be executed
until condition
Example:
local counter = 1
repeat
print("Counter value: " .. counter)
counter = counter + 1
until counter > 5
This loop produces the same output as the previous example.
for loop
The for loop allows you to iterate over a range of values. You usually use it when the number of iterations is known in advance. There are two types of for loops in Lua: numeric and generic. You use the numeric for loop to iterate over a sequence of numbers, while you can use the generic for loop to iterate over other types of sequences.
Numeric for loop
for startValue, endValue, stepValue do
-- code block to be executed for each iteration
end
Example:
for i = 1, 5, 1 do
print("Iteration: " .. i)
end
The output will be:
Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
Iteration: 5
Generic for loop
for index, value in ipairs(sequence) do
-- code block to be executed for each iteration
end
Example:
local fruits = {"apple", "banana", "orange"}
for index, fruit in ipairs(fruits) do
print("Fruit at index " .. index .. ": " .. fruit)
end
The output will be:
Fruit at index 1: apple
Fruit at index 2: banana
Fruit at index 3: orange
Control statements for loops
In Lua, you can use control statements to change the flow of loops. These statements include:
break statement
Ends the loop prematurely when a certain condition is met. Once break is executed, the program flow jumps out of the loop and continues with the next line of code after the loop.
Example:
for i = 1, 10 do
if i == 5 then
break
end
print(i)
end
-- This will print numbers from 1 to 4. The loop terminates when i equals 5.
The output will be:
1
2
3
4
Mimicking the continue statement
Lua doesn’t have a continue statement like some other languages. The basic idea of continue is to skip the current iteration and move on to the next one.
In Lua, you can achieve this effect using a combination of goto and labels.
Example:
for i = 1, 10 do
if i % 2 == 0 then
goto continue
end
print(i) -- Will print only odd numbers between 1 and 10.
::continue::
end
The output will be:
1
3
5
7
9
Here, when i is an even number, the program flow jumps to the label ::continue::, effectively skipping the print(i) statement for even numbers.
It’s important to be careful when using control statements, as they can make your code more complex and harder to maintain.
Don’t forget to test your loops thoroughly to make sure they behave as expected and to avoid potential pitfalls like infinite loops.
