How do I generate a hashcode from a byte array in C#?

Question

Say I have an object that stores a byte array and I want to be able to efficiently generate a hashcode for it. I\'ve used the cryptographic hash functions for this in the pa

Answer 1

Borrowing from the code generated by JetBrains software, I have settled on this function:

    public override int GetHashCode()
    {
        unchecked
        {
            var result = 0;
            foreach (byte b in _key)
                result = (result*31) ^ b;
            return result;
        }
    }

The problem with just XOring the bytes is that 3/4 (3 bytes) of the returned value has only 2 possible values (all on or all off). This spreads the bits around a little more.

Setting a breakpoint in Equals was a good suggestion. Adding about 200,000 entries of my data to a Dictionary, sees about 10 Equals calls (or 1/20,000).