Using 'ipairs' on a table without an array part is likely a bug

[polarstecFR (Fabien)]

I’m currently following a tutorial to learn scripts, and this problem suddenly popped up and I don’t understand why, I tried to look for the solution in the forum but I don’t understand the problem…

the other day it was with a scripter (with a good level) who didn’t know how to correct it

Can you explain to me?

[TheRealANDRO (ANDRO)]

I’ve already made an answer to another problem like this a short while ago:

"Using # On a table without a array part is more likely a bug"

Dictionaries do not support the # operator, because tables in Lua work differently than in other languages. Basically, arrays and dictionaries are actually the same, but for arrays, the index (key) is automatically set for each value. For example, a table like {1,2,3} is actually {[1] = 1, [2] = 2, [3] = 3} under the hood. And because of this, Lua can actually figure out how many elements are inside an array, because it’s automatically ordered. And that’s why the # operator only works on array…

Basically, tables have two types: Arrays and Dictionaries.
They’re technically the same, however, they cause different behaviors in loops.

For your problem, use: for tool, toolTable in toolConfig do and that should solve your issue.

[NyrionDev (Nyrion)]

For dictionaries you must use pairs instead of ipairs:

for tool, toolTable in pairs(toolConfig) do --pairs not ipairs!

[polarstecFR (Fabien)]

Yes, but why in the tutorial he do that and without error ? i dont understand that

Was it over 2 years ago?

[TheRealANDRO (ANDRO)]

Dictionaries and Arrays worked the same for many years, that’s a faulty tutorial.

@NyrionDev

For dictionaries you must use pairs instead of ipairs:

using pairs() is quite unnecessary nowadays, as Luau now automatically handles that internally. Just using for tool, toolTable in toolConfig do would be enough.

[Tomi1231 (Chilly28)]

That warning is pretty recent I think. I believe it came with the lua type checking stuff, now that it is able to determine the types of a table (having string indexes, rather than number indexes), it is able to throw a warning when you try to use ipairs on a table that doesn’t have number indexes

[TheRealANDRO (ANDRO)]

Luau can’t loop over a string or other types of indexes (keys), only with number indexes it is able to find the value. Because a string can be anything wheres a number is a number. Otherwise, Dictionaries and Arrays are pretty much the same.