Whats the difference between for i, in pairs and for i, in ipairs?

Help and Feedback Scripting Support
#1

I’m trying to get a folders children individually and I’m using for _, PlacedObject in pairs(Plot.PlacedObjects:GetChildren()) do

But it doesn’t seem to run so should I use ipairs instead and even is the difference?

#2

There’s no true difference between pairs and ipairs except that ipairs will iterate through a dictionary and stop running if an index is nil, however it will run through the indexes in order. That is the main difference, as pairs will not always iterate in order. For example…

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

for i, v in ipairs(t) do
    print(i, v) --> "Hello"
end

for i, v in pairs(t) do
    print(i, v) --> "World!" "Hello"
end

However, to solve your problem, make sure there’s actually children, or else the pairs loop wont run.

#3

What if first the Placed Objects has no children but when my function restarts that for i loop will it work or no. Because its a build system so when you join there are no children until you place stuff

#4

Well, you’d have to do it every time a child is added. For example

local function childAdded()
    for i, v in pairs(folder:GetChildren()) do
        --do stuff
    end
end

folder.ChildAdded:Connect(childAdded)
#5 
local function Save(plr)
	local Key = "plr-"..plr.UserId
	if Plot then
		local save = {}
		print("SAVE = {}")
		for i, Obj in pairs(Plot.PlacedObjects:GetChildren()) do
			print("Attempt Save")
			if Obj then
				print("Attempt table.insert")
				table.insert(save, {
					ObjectName = Obj.Name,
					
					CFrames = {
						X = Obj.PrimaryPart.CFrame.X,
						Y = Obj.PrimaryPart.CFrame.Y,
						Z = Obj.PrimaryPart.CFrame.Z,
						Orientation = Obj.PrimaryPart.Orientation.Y
					}
				})
			end
		end
		
		for _, Saves in pairs(save) do
			for _, a in pairs(Saves) do
				print(a)
			end
		end
		local success, err = pcall(function()
			PlotSave:SetAsync(Key, save)
		end)
		if not success then
			warn("Plot Data failed to save: "..err)
			return
		end
	else
		GetPlot(plr)
	end
end

You see how this is a function, if the function is fired will it still restart the loop. The print(“attempt save”) doesn’t fire

#6

Basically, this man has the answer.

1 Like
#7

Hey you helped me on the other post… i added some prints and one part of the script nevers prints:

local function Save(plr)
	local Key = "plr-"..plr.UserId
	if Plot then
		local save = {}
		print("SAVE = {}")
		for i, Obj in pairs(Plot.PlacedObjects:GetChildren()) do
			print("Attempt Save")
			if Obj then
				print("Attempt table.insert")
				table.insert(save, {
					ObjectName = Obj.Name,
					
					CFrames = {
						X = Obj.PrimaryPart.CFrame.X,
						Y = Obj.PrimaryPart.CFrame.Y,
						Z = Obj.PrimaryPart.CFrame.Z,
						Orientation = Obj.PrimaryPart.Orientation.Y
					}
				})
			end
		end
		
		for _, Saves in pairs(save) do
			for _, a in pairs(Saves) do
				print(a)
			end
		end
		local success, err = pcall(function()
			PlotSave:SetAsync(Key, save)
		end)
		if not success then
			warn("Plot Data failed to save: "..err)
			return
		end
	else
		GetPlot(plr)
	end
end

The print("attempt save)

#8

Now that’s becoming off-topic, and is not on the goal of this topic. You should instead try to solve the issue you want here, by either making a topic, or by “reviving” that one topic you made.

#9

If you are iterating through the results of a call to GetChildren, you can use ipairs, since GetChildren will always return an array.