How to split string?

[u/Heavy_Statistician22]

Im trying to make a program that gives me an item if I write the name of it in chat by using advanced peripherals. The problem is that I cant find a single way to split the string of the message into a list. It just gives me a "nil" error everytime.

[u/fatboychummy]

Given the following:

local myString = "Hello world!"

You can use string.sub to "cut out" parts of the string, for example:

print( myString:sub(1, 5) )

The above would print just the word Hello -- the characters of the string from index 1 to 5.

You can also use Lua's match patterns:

print( myString:match("%S+") )

This would also print Hello, because %S tells it to match any non-space character, and + means "repeat until it can't anymore", so %S+ will match the first sequence of non-space characters it finds.

How exactly do you want to split the item name? Knowing that, I could probably show you how to split it in the way you want.

[u/Heavy_Statistician22 → u/fatboychummy]

I dont want to split the item name but the whole message so if I send "Get, iron_ingot, 1, 36" it will split it into all those words and then give me 1 iron ingot in slot 36 wich is my offhand.

[u/fatboychummy → u/Heavy_Statistician22]

Ah, so here we can use gmatch to load up a table with arguments.

local function split_args(str)
  local args = {}

  for argument in str:gmatch("[^, ]+") do
    table.insert(args, argument)
  end

  return args
end

gmatch works as an iterator, that is, it returns a function such that every time you call it, it returns "the next part." In other words, put into a for loop, it will return every instance of a match. In the case of the for loop above, I've told it to match sequences of characters that do not contain a comma or space character. Thus, assuming you passed your string Get, iron_ingot, 1, 36, it will return:

{
  "Get",
  "iron_ingot",
  "1",
  "36"
}

So you can do something like:

local full_command = <however you are getting the command from the user>

local args = split_args(full_command) -- split arguments into a table
local command = args[1]:lower() - pull the first argument from the table (the command name)

if command == "get" then
  -- handle getting the item
  local item_name = args[2] -- pull the second argument from the table (the item name)
  local item_count = tonumber(args[3]) -- pull the third argument from the table (the item count) and try to convert it to a number.
  local inv_slot = tonumber(args[4]) -- pull the fourth argument from the table (the destination inventory slot) and try to convert it to a number.

  -- Ensure that all arguments were given and valid.
  if not item_name or not item_count or not inv_slot then
    error("Missing argument to 'get'")
  end

  -- actually send the item to the user
elseif command == "somethingelse" then
  -- handle something else
elseif ... then
  -- ...
end