"Attempt to get length of nil value"?

Help and Feedback Scripting Support
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#1

I am making a character selection screen for a game I’m working on, but whenever I use the arrows, it returns “Attempt to get length of nil value”. Any idea why this is happening?
Here is the code

local CurrentPokemon = "Mudkip"

local PokemonList = {
	"Bulbasaur", "Charmander", "Squirtle",
	"Pikachu", "Chikorita", "Cyndaquil",
	"Totodile", "Treecko", "Torchic",
	"Mudkip", "Skitty", "Riolu"
}

MouseButton1Down = function()
			local PokemonNumber = #PokemonList[CurrentPokemon]
			if PokemonNumber == #PokemonList then
				PokemonNumber = #PokemonList
			else
				PokemonNumber = #PokemonList[CurrentPokemon] + 1
			end
			CurrentPokemon = PokemonList[PokemonNumber]
			
			local IconContainer = PokemonData:WaitForChild("IconContainer")
			local Icon = IconContainer:WaitForChild("Icon")
			Icon.Image = ("rbxassetid://"..Images[CurrentPokemon])
			
			local Name = PokemonData:WaitForChild("Name")
			local Typing = PokemonData:WaitForChild("Typing")
			local Button = PokemonData:WaitForChild("Button")
			
			Name.Text = CurrentPokemon
			Typing.Text = ("Typing: "..CurrentPokemon)
			Button.Text = ("Choose "..CurrentPokemon.."?")
			
			TweenService:Create(Camera,
				TweenInfo.new(1.0,
					Enum.EasingStyle.Quart,
					Enum.EasingDirection.Out),
				{CFrame = CamerasFolder[CurrentPokemon].CFrame}
			)
		end
#2

I think you need to loop through the table using a for loop also if you’re making a pokemon game it’ll get taken down very quickly

1 Like
#3

Hello, I believe the error comes in this line, local PokemonNumber = #PokemonList[CurrentPokemon], you are trying to get length but it returns nil, Instead try this, local PokemonNumber = table.find(PokemonList, CurrentPokemon)
Tell me if that fixes it.

#4

I understand this, I don’t plan to release this, this is simply to expand my knowledge by making something I enjoy making, and that I am passionate about.

1 Like
#5

Try this out and lmk if there’s any more errors. I obviously don’t have the code so I can’t properly test.

local CurrentPokemon = "Mudkip"

local PokemonList = {
	"Bulbasaur", "Charmander", "Squirtle",
	"Pikachu", "Chikorita", "Cyndaquil",
	"Totodile", "Treecko", "Torchic",
	"Mudkip", "Skitty", "Riolu"
}

MouseButton1Down = function()
	local PokemonNumber = table.find(PokemonList, CurrentPokemon) or 1
	
	-- Wrapping back to the start if we've reached the end!
	PokemonNumber = (PokemonNumber % #PokemonList) + 1

	CurrentPokemon = PokemonList[PokemonNumber]

	local IconContainer = PokemonData:WaitForChild("IconContainer")
	local Icon = IconContainer:WaitForChild("Icon")
	Icon.Image = ("rbxassetid://"..Images[CurrentPokemon])

	local Name = PokemonData:WaitForChild("Name")
	local Typing = PokemonData:WaitForChild("Typing")
	local Button = PokemonData:WaitForChild("Button")

	Name.Text = CurrentPokemon
	Typing.Text = ("Typing: "..CurrentPokemon)
	Button.Text = ("Choose "..CurrentPokemon.."?")

	TweenService:Create(Camera,
		TweenInfo.new(1.0,
			Enum.EasingStyle.Quart,
			Enum.EasingDirection.Out),
		{CFrame = CamerasFolder[CurrentPokemon].CFrame}
	)
end
1 Like
#6

PokemonList is an array so the keys are only numbers
try using table.find() if you want to get the index

local CurrentPokemon = "Mudkip"
local PokemonList = { "Bulbasaur", "Charmander", "Squirtle", "Mudkip" }
print(PokemonList[CurrentPokemon]) -- prints nil

local CurrentPokemon = "Mudkip"
local PokemonList = { "Bulbasaur", "Charmander", "Squirtle", "Mudkip" }
print(table.find(PokemonList, CurrentPokemon) --  prints 4
#7

IT WORKSS!!! Thanks to all of your help it works amazingly now! Thank you all so much!

#8

No worries!

As they said, PokemonList is what’s called an array which just means it’s an ordered list of values, each one having an index starting at one, and counting upwards for every additional element in the array. Because of this, in order to retrieve a value from it, you have to give the index position (a number) of the item in the array. Dictionaries are lists of keys who’s indexes can be strings, numbers, or objects.

Now from looking at your code it seems like you understood this concept for the most part as you were at times indexing the array with a number value, but you’d frequently put #PokemonList["Mudkip"]. Now what’s going on here is the script tries to search for the index "Mudkip" in the array (which we’ve already established we can only index ordered arrays with numbers, and dictionaries with strings), and then it was trying to call #nil because PokemonList["Mudkip"] returns nil.

I know it’s quite the long explanation, but I hope this helps you better understand arrays and how to use them, as well as the quirks of debugging odd errors like these! Order of operations matters, and even a seasoned programmer may have to do a double take to figure out why exactly the error is written our the way it is.

2 Likes
#9

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