CODEWITHSUNDEEP
luacoronasdk
Josh Wa
Josh Wa

Reputation: 1049

Corona SDK (LUA) - Trouble With Inserting Into Table

I have searched around quite a bit and couldn't quite find a solution for this. Any help you can offer would be appreciated.

-- The array compiled of enemies only allowed in the current
-- level phase
local EnemyList = {}
-- Counter to determine the next spot in the EnemyList
-- array to insert into
local counter   = 1

for i=1,#Enemies do
    if Enemies[i].phase == 0 or Enemies[i].phase == which_phase then
        EnemyList[counter].src      = Enemies[i].src
        EnemyList[counter].exp      = Enemies[i].exp
        counter                     = counter + 1
    end
end

I am getting an error about attempting to index a nil value, in reference to the EnemyList table/array. What I am trying to accomplish is I am trying to compile a new array of only enemies that are allowed. I guess I am unsure how to insert a new row into the EnemyList table. I tried using table.insert, but the value parameter is required, and I am not sure how to do that with the fact that I am storing multiple values into the EnemyList array.

Any help or insight on the proper way to insert a new row into an empty table/array would be much appreciated. Thanks!

EDIT: I got a working solution, but I figured I should update the code here if anyone in the future finds it.

-- The array compiled of enemies only allowed in the current
-- level phase
local EnemyList = {}

for i=1,#Enemies do
    if Enemies[i].phase == 0 or Enemies[i].phase == which_phase then
        table.insert( EnemyList, { src = Enemies[i].src, exp = Enemies[i].exp } )
    end
end

Upvotes: 0

Views: 1974

Answers (1)

user1131435
user1131435

Reputation:

You can store tables within tables in Lua. Tables are indexed in one of two ways: First, by index number. This is what table.insert uses; it will add an entry at the next index number.

The second way is by key; e.g.

> t = {}
> t.test = {}
> =t.test
table: 0077D320

You can insert tables into tables; this is how you create a 2D table. Because of the way you've defined your tables, type(EnemyList[counter]) = table.

You can insert new entries into tables by running table.insert(table, value). This will assign value to the next available numeric entry. type(value) can also be a table; this is how you create "multidimensional arrays" in Lua.

As an aside, instead of using for i=1,#Enemies I would suggest using for i,v in ipairs(Enemies). The second one will iterate over all numerical entries in the Enemies table.

Upvotes: 2

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