What is the runtime of array.length?
java
Solution
`array.length` is O(1) and the loop is O(n) overall (assuming the "something" is constant-time).
Is it different for c?
C is different in that, depending on how the array is allocated, you can either find out its size in `O(1)` time or not at all. By "not at all" I mean that you have to keep track of the size yourself.
(On a personal note, if that's the caliber of interviewers, I would have reservations about coming to work there.)
Problem
Let's say I have an array: ``` int[] array = new int[10]; ``` What is the runtime of: ``` int len = array.length; ``` I would think that this would be a constant time operations, but today in an interview, the interviewer told me that this would be `O(n)` because the number of elements would need to be counted. Additionally, if I have a loop like this: ``` for (int i = array.length - 1; i >=0; i--) { something with array[i]; } ``` Does this entail an extra `n` operations to get to the end of the array to start the loop? The interviewer came from a C background, so maybe they were mistaken about how Java works, but I didn't want to push it during the interview.