Addressing an index in array in Lua

Question

I am trying to write a simple game using Love 2d engine. It uses lua as the scripting language. I have some problems with arrays and can't find any solution. Here is my issue:

for i = 1, 10 do 
    objects.asteroids = {} 
    objects.asteroids[i] = {} 
    objects.asteroids[i].body = love.physics.newBody(world, 650/2, 650/2, "dynamic")
    objects.asteroids[i].size = 3 
    objects.asteroids[i].angle = math.random(6) 
end

In the same function I am trying to do a following operation:

for i = 1, 10 do 
    objects.asteroids[i].size = 2 
end

And I get this error when trying to run my game:

Error main.lua:48: attempt to index a nil value

Where line 48 refers to this line of code:

objects.asteroids[i].size = 2

score 2 · Accepted Answer · answered Jan 19 '14 at 23:38

You're overwriting objects.asteroids on each loop iteration.

for i = 1, 10 do
  objects.asteroids = {} -- <== Here.
  objects.asteroids[i] = {}

What this means is that the asteroid objects that you're trying to add end up being erased on the next step of the loop, since object.asteroids is set to a new {} table and the old one becomes inaccessible thereafter.

You might want to rearrange it like so:

objects.asteroids = {}

for i = 1, 10 do
  objects.asteroids[i] = {}
  -- ...

Thanks, now it seems so trivial :). – Paweł Jastrzębski Jan 21 '14 at 16:42 — Paweł Jastrzębski, Jan 21 '14 at 16:42

Addressing an index in array in Lua

1 Answers1