Error claims a value is nil, which makes no sense

[dyl4n130]

Everytime I attempt to run my code I get an error that says a value in my if statement is nil.

The if statement in question:

Code: Select all

elseif rX[i] < rX[n] + 2 and rX[n] < rX[i] + 2 and rY[i] < rY[n] + 2 and rY[n] < rY[i] + 2 then

Ive managed to narrow it down to it thinking that rX[n] is nil. The absolutely baffling thing is that they are both being called from this:

Code: Select all

for i = 1, #rX do
    for n = 1, #rX do
      if isCollided(i, n) then

Which means that i and n are the same value. So it is literelly comparing rX[1] and rX[1] and says that one is nil and the other is fine. Does anyone have any idea what this could mean? I have tried everything I can think of, at this point I'm certain the solution is some dumb typo I made that is just flying over my head. Here is all the relevant code:

Code: Select all

function doFights()
  for i = 1, #rX do
    for n = 1, #rX do
      if isCollided(i, n) then
        if rS[i] > rS[n] then
          table.remove(rX, n)
          table.remove(rY, n)
          table.remove(rS, n)
        elseif rS[i] < rS[n] then
          table.remove(rX, i)
          table.remove(rY, i)
          table.remove(rS, i)
        elseif rS[i] == rS[n] then
          if love.math.random(0, 1) == 0 then
            table.remove(rX, n)
            table.remove(rY, n)
            table.remove(rS, n)
          else
            table.remove(rX, i)
            table.remove(rY, i)
            table.remove(rS, i)
          end
        end
      end
    end
  end
end

function isCollided(i, n)
  if rX[i] < rX[n] + 2 and rX[n] < rX[i] + 2 and rY[i] < rY[n] + 2 and rY[n] < rY[i] + 2 then
    return 1
  else
    return 0
  end
end

[dyl4n130]

So the problem is definitley in the `n` for loop. In other areas I replaced n with 1 and it ran fine. So the loop that does i works fine, but the exact same loop with a differnent letter doesnt work. This is really annoying

[raidho36]

If you want to remove table elements mid-loop you need to loop backwards.

[dyl4n130]

If you want to remove table elements mid-loop you need to loop backwards.

could you elaborate? I dont think that is the problem since the program crashes before it even gets to the table.remove

[raidho36]

If you remove a table element, it will be shorter than it was when you started looping, so last loop indices will be out of range and produce nil. I'm sure that's your problem. Just loop it backwards.

[Sir_Silver]

What raidho means is, instead of iterating from 1 to the # of your table, iterate from the # of your table to 1 stepping by -1:

Code: Select all

for i = #my_table, 1, -1 do

end

[dyl4n130]

If you remove a table element, it will be shorter than it was when you started looping, so last loop indices will be out of range and produce nil. I'm sure that's your problem. Just loop it backwards.

did that, same problem. it returns nil before table elements start getting removed

[dyl4n130]

What raidho means is, instead of iterating from 1 to the # of your table, iterate from the # of your table to 1 stepping by -1:

Code: Select all

for i = #my_table, 1, -1 do

end

thats what i thought he meant, didnt work though

[raidho36]

Then it must be your other table. If it's not the same length it would return nil on trailing elements.

[dyl4n130]

Then it must be your other table. If it's not the same length it would return nil on trailing elements.

all the tables have to be the same length. they are all defined within the same for loop in love.load