10-digit index beyond bounds [0 .. 1]

[architectpianist]

Hi,
Take a look at this code:

NSLog(@"count = %i", [[connectDotsLineX objectAtIndex:index] count]);
		for (int newIndex = 0; newIndex < [[connectDotsLineX objectAtIndex:index] count]; newIndex++) 
		{
			int x1, x2, y1, y2;
			int previousIndex = newIndex - 1;
			x1 = [[[connectDotsLineX objectAtIndex:index] objectAtIndex:previousIndex] intValue];
			x2 = [[[connectDotsLineX objectAtIndex:index] objectAtIndex:newIndex] intValue];
			y1 = [[[connectDotsLineY objectAtIndex:index] objectAtIndex:previousIndex] intValue];
			y2 = [[[connectDotsLineY objectAtIndex:index] objectAtIndex:newIndex] intValue];
...

There doesn't appear to be anything wrong with it to me, but then I'm only a beginner. This section is giving me:

2011-03-01 09:55:24.737 The Escherizer[89042:207] count = 2
2011-03-01 09:55:24.739 The Escherizer[89042:207] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSMutableArray objectAtIndex:]: index 4294967295 beyond bounds [0 .. 1]'

Where did the 4294967295 come from?!? Only after I added those last 6 lines did it give me this exception. What is going on here?
Thanks!

[TUX2K]

the 4294967295 looks like a pointer.

maybe you should rewrite your code so that is easier to debug.

[simplyDusty]

Where are you getting 'index' from?

[mariano_donati]

Have you initialized index?... it looks like a trash value for me.

[lgehrig1]

0 - 1 = 4294967295

Your key line is as follows:

int previousIndex = newIndex - 1;

Because newIndex starts at 0, and you are subtracting 1, you get -1 (0x00000000 - 0x00000001 = 0xffffffff).

I'm not really looking at your code to try & figure out what it's doing, but if you need "now" and "then" you'll need to start at pos 1 on your outer loop, and do something special to handle your very first 0'th position.