Index out of range in for loop

Question

So I am working on a game, aside from a game engine, and I have a for loop to detect collisions with all objects in a list of Panels

Here is the code:

for (int x = 1; x <= 2; x++)
{
    if (player.obj.Bounds.IntersectsWith(walls[x].Bounds))
    {
       MessageBox.Show("COLLIDING");
    }
}

Currently there are only two objects added to the list called walls And everytime I go to run it tells me Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index I don't know what to do, am I setting up the if statement wrong?

I just tried taking it out of the for loop and replaced x with 0, and when I touched that object it said I was colliding, so I know I didn't set up the if statement wrong.

score 3 · Accepted Answer · edited May 24 '16 at 01:04

3

As you may or may not know, arrays start at 0 in the index, so your array should be like so.

for (int x = 0; x < 2; x++) 
{
    if (player.obj.Bounds.IntersectsWith(walls[x].Bounds)) 
    {
        MessageBox.Show("COLLIDING");
    }
}

edited May 24 '16 at 01:04

sujith karivelil

28,671
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answered May 24 '16 at 01:00

C. Knapp

74
3

I still get an error when I do that – Engine Dev May 24 '16 at 01:09
Did you remember to have `x < 2` instead of `x <= 2` ? How long is the walls[] array? – C. Knapp May 24 '16 at 01:12
Ok, I fixed it thanks a lot! – Engine Dev May 24 '16 at 01:18
No problem. Good luck with your game! – C. Knapp May 24 '16 at 01:19

score 1 · Answer 2 · answered May 24 '16 at 00:57

If there are 2 objects in walls the loop needs not go to x = 2

  for (int x = 0; x < 2; x++)
        {
            if (player.obj.Bounds.IntersectsWith(walls[x].Bounds))
            {
                MessageBox.Show("COLLIDING");
            }
        }

As Arrays start at index 0

sujith karivelil · Answer 3 · 2016-05-24T01:33:16.310

You have two elements in the walls[] array means they ware located in walls[0] and walls[1]( Since .Net arrays are following 0 based indexing) and hence walls[2] is out of bound; So you should start the loop with 0 to get the first element and loop up to 2. But i strongly recommend you to use length of walls instead of 2

for (int x = 0; x < walls.Length; x++)
{
    if (player.obj.Bounds.IntersectsWith(walls[x].Bounds))
    {
        MessageBox.Show("COLLIDING");
    }
}

Index out of range in for loop

3 Answers3