The break Statement

Sometimes you don't need to go through the whole loop. When you're looking for something and you find it, there's no reason to keep looking. The break statement ends the loop right away, and the program continues after the loop's end.

Hugo the trader comes every other day, and it rains every 3rd day. On which day does Hugo first come in the rain? The loop prints each day it checks, so you can see where it stops:

for day = 1, 30 do
    print("Checking day " .. day)
    if day % 2 == 0 and day % 3 == 0 then
        print("Hugo comes in the rain on day " .. day)
        break
    end
end
print("Done")

Checking day 1
Checking day 2
Checking day 3
Checking day 4
Checking day 5
Checking day 6
Hugo comes in the rain on day 6
Done

On day 6, the condition is true. The program prints the result, and break ends the loop: days 7 to 30 are never checked, and the program goes on with print("Done"). Without break, the loop would go all the way to day 30 and also report days 12, 18, 24 and 30.

You'll almost always put break inside an if; on its own, it would end the loop in its first iteration. It works the same way in while, for and repeat loops. You'll also see Lua programs with while true do: a loop whose condition is always true. It would never end by itself, so somewhere inside, it has an if with break.

To know after the loop what you found, store it in a variable created before the loop. If the loop finds nothing, the variable stays nil, and an if can tell. Grandpa Joe visits every 4th day and Hugo every 6th day. Do they meet in the first 10 days?

local meeting
for day = 1, 10 do
    if day % 4 == 0 and day % 6 == 0 then
        meeting = day
        break
    end
end
if meeting then
    print("They meet on day " .. meeting)
else
    print("They don't meet")
end

They don't meet

With for day = 1, 20 do, the program would print They meet on day 12.

Lua has no continue. In many languages, continue skips the rest of the current iteration and goes on to the next one. Lua doesn't know it: it takes continue for a variable name and then stumbles over the end after it. The program doesn't even start:

for day = 1, 4 do
    if day == 2 then
        continue
    end
    print("Day " .. day)
end

main.lua:4: syntax error near 'end'

Instead, put the rest of the block in an if with the opposite condition:

for day = 1, 4 do
    if day ~= 2 then
        print("Day " .. day)
    end
end

Day 1
Day 3
Day 4

(Lua also has goto, which can jump to the end of the block, but you won't need it in this course. Roblox's Luau has continue; standard Lua doesn't.)