3D int array causing Object reference errors

Question

I've written a script for an enemy that moves along tiles on a grid, which is a 3D array with the first dimension being horizontal position, second vertical position and 3rd properties of the space. I have not referenced any objects, yet when I run the script it causes an "Object reference not set to an instance of an object" error.

public bool my_turn;
public bool turn_setup;
public List<int> my_grid_pos;
public List<List<List<int>>> grid;
void Update () {
    if(my_turn)
    {
         if (turn_setup)
         {
             grid[my_grid_pos[1]][my_grid_pos[0]][2] = 1;
         }
    }
}

Fredrik Schön · Accepted Answer · 2019-06-07T15:59:58.663

"I have not referenced any objects"

Yes, you are. On this line you're trying to reference 4 objects:

grid[my_grid_pos[1]][my_grid_pos[0]][2]

my_grid_pos[1]
my_grid_pos[0]
grid[x, y]
grid[x, y][2]

One (or more) of these list queries results is resulting in a null value, for some reason or another, that we cannot deduct from the code you've posted. You then try to access one of its list's objects:

null[x]

This results in the error you're getting.

Here's an answer explaining what NRE is

3D int array causing Object reference errors

1 Answers1