Looping in tables without using pairs() & ipairs()

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#1

is looping in tables without using pairs() & ipairs() a bad habit?
and why i should use them?

what i understaned that ipairs will loop in order
while pairs won’t in mose cases

but what about not using any of them?

#2

Depends on the use case whether looping through a table is necessary or not. But there will be many cases where you just have to loop through tables. For example, game.Players:GetPlayers() returns a table of the players in game, and you may want to teleport them to your minigame map. Looping through that table would be the most efficient way to go about it.

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#3
#4

Using pairs & ipairs is not exactly a bad habit.

These are called enhanced for loops (meaning they pull all keys & values out of the list/dictionary/etc…)

Let’s say you had a dictionary or an unsorted array, doing the following will not work.
The reason I am showing this is, it is how in most other programming languages you would iterate through a (sorted) list.

local list = {
[1] = "Hello, ",
[3] = "World!"
}

print(#list)
-- length is printed as 1

for i=1, #list,1 do
print(list[i])
end
-- prints "Hello, ", but not "World!"

To avoid issues like this, I would just recommend using pairs.
In the few cases you need to use an iterator (ipairs), make sure the list is always sorted, and then just use ipairs.

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#5

I’m pretty sure they don’t work for dictionary type tables, so remember that

#6

Roblox actually reccomends iterating without pairs or ipairs. These two things exist because it was there before Roblox transitioned from Lua to Luau. You can use them if you want, but not using them isn’t bad practice, either.

The default iterator iterates sequentially if it’s an array, and as a dictionary if it’s not sequential. You shouldn’t be building non-sequential arrays anyway (obviously with a few exceptions).

They do.

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#7

Use generalized iteration (no pairs/ipairs). the only time you’ll ever need to use ipairs is if you want the specific functionality of the iteration stopping for one case.

I’ve been using it a least a year with no issues, so don’t let people tell you otherwise

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#8

they do like mentioned before, just not ipairs

#9

You should use in 99% of the time. In short, it is a generalized version created by Roblox that either handle every possible use case in a single function or automatically chooses the right iterator function among pairs, ipairs, next, and others. It is also much faster and more performant, as it has been optimized by Roblox, and it reduces the length of your for i,v in do loops while removing the annoying brackets.

As for the remaining 1%, it is for very specific cases where you might want to do something a bit unusual or tricky that requires using a certain iterator function.

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#10

I’ve seen people use next before, but I’ve also seen people just iterate over a dictionary or table directly in the form of for i, v in t do. Plenty of options here, but as people will come to discover, there usually are in a variety of cases in programming where people will stand by one methodology over the other.

#11
  • pairs just returns the next iterator, the table to be traversed, and the starting key of nil. This is pretty outdated, and is surpassed by more efficient methods. I wouldn’t recommend using it.
  • ipairs is like pairs, but only iterates over array tables. It’s still pretty quick and could be worth using.

Generalised iteration is probably the best option, like the others have said. Roblox will select the best method to iterate over the table. Also, it allows you to define a custom iterator with the __iter metamethod in your tables! (must return the iterator from the metamethod tho)

#12

Thanks @ardrous @rman501 @BlueBloxBlast @wastbo @T3_MasterGamer @Crygen54 @StrengthThroughFaith @12345koip for the Information
i understand now
and big thanks to the fart guy @VegetationBush (:

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#13

Thanks for the extra Information

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