How to hash an int[] in c#

.net, c#, hash, int

Solution

You can use something like this:

public static int CombineHashCodes(params int[] hashCodes)
{
    if (hashCodes == null)
    {
        throw new ArgumentNullException("hashCodes");
    }

    if (hashCodes.Length == 0)
    {
        throw new IndexOutOfRangeException();
    }

    if (hashCodes.Length == 1)
    {
        return hashCodes[0];
    }

    var result = hashCodes[0];

    for (var i = 1; i < hashCodes.Length; i++)
    {
        result = CombineHashCodes(result, hashCodes[i]);
    }

    return result;
}

private static int CombineHashCodes(int h1, int h2)
{
    return (h1 << 5) + h1 ^ h2;

    // another implementation
    //unchecked
    //{
    //    var hash = 17;

    //    hash = hash * 23 + h1;
    //    hash = hash * 23 + h2;

    //    return hash;
    //}
}

Problem

I'm trying to think of a way to override GetHashCode() when called from a Vector2[]. This code produces non unique hashes for objects that I know to be equal: I pass the following class the same rectangle, and different hash codes are generated. ``` public Shape(Rectangle r) { edges = new Vector2[4]; edges[0] = new Vector2(0, 0); edges[1] = new Vector2(r.Width, 0); edges[2] = new Vector2(r.Width, r.Height); edges[3] = new Vector2(0, r.Height); Console.Write(edges.GetHashCode() + "\n"); Position = new Vector2(r.X, r.Y); } ``` A Vector2 array is just bunch of ints. How can I create a unique hash for a list of ints?

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