Does in_array() use a binary search algorithm?

Question

I have a largish array of string that I want to use as a look-up.

I am using in_array(), but I suspect its doing a simple loop through - does anyone know whether the in_array() algo uses a bsearch algo?

Answer 1

in_array() is O(n). Also see List of Big-O for PHP functions

Answer 2

Since it doesn't require the array to be sorted, I don't see how it could do a binary search.

Answer 3

in_array() uses a linear (O(n)) search rather than a binary (O(log n)) search.

If you want O(log n) or better I would suggest you either put the values you want to search as the keys in an array or you create an index structure that effectively does the same thing.