1) The maxint was just an example and these tests are not limited to arrays. For the same I was talking about bytes. And comparing a byte value against 255 + 1 is still wrong.

So yes, test inclusively, but not only the special cases, but always. It will prevent bugs, make code more readable and give faster code,

Only it's not what Dijkstra advocates.

2) When iterating 20 <= i < 30 or 20 <= i <= 29 the result is the same. At the end of the loop i will be 30, so in both cases the next lower bound = previous upper bound + 1.

While typing I thought of a case where inclusive might be more confusing, When iterating to first + n. Then < would be better than <= first + n - 1.

But I think this has little to do with if 0 or 1 based arrays are better. Only the start is different, after that it's all the same.