Compute hash function in range 0..n

Question

I have an array of strings. Array has length n. How to compute hash key for each string, so each key will be a number in range of 0..n?

UPDATE

Array's items could be not strings, but numbers if it will helps to someone to help me ;)

Answer 1

Try modulo N:

int N = array.Length;
int hashMaxN = strings[i].GetHashCode() % N;

This will not guarantee unique hashes for different indices. But a hash code isn't unique.

If you want a unique id assigned to each string in a list, then use the suggestion from anothe r answer: pick the strings index in the sorted array of distinct strings

int itemHash = myList.Distinct().OrderBy(s => s).IndexOf(item);

This will have the property of being the same for the same string regardless of how the list is ordered but adding a string to the list will change the hash codes for the items.