How to check if array is already sorted

Question

so how to make such logic

int[] arr = {2, 5, 3};

if (/* arr is sorted */)
    ....
else 
    ...

Its bad that method Array.sort is void

Answer 1

Well you can check it in O(n) worst case linear time. A non-sorted array (assuming you mean sorting in ascending order) will have a trip point. That is at some point arr[i] > arr[i+1]

All you need to do is

boolean is_array_sorted(int arr[]) {
  for(int i=0; i < arr.len-1; i++) {
    if(arr[i] > arr[i+1]) {
       return false;
    }
  }
  return true;
}

Just change the > to < if your array sort is supposed to be descending order