.NET equivalent to java.util.Arrays.hashCode() function for arrays of intrinsic types?

Question

Is there a.NET utility class equivalent to java.util.Arrays.hashCode() for arrays of intrinsic types such as int[], short[], float[], etc.?

Obviously I could write my own utility class but was trying to find one already available in the .NET framework.

Answer 1

I'm pretty sure there's nothing in the framework itself that does this. There may well be some third-party implementations, but there's nothing built-in (and public).

Answer 2

I'm not aware of such a thing being built-into .Net up to version 3.5, although .Net 4 is very likely to support it natively via the IStructuralEquatable interface which Array will implement (thanks to Greg Beech for pointing that out).

Here's a simple implementation using an extension method on IEnumerable.

int HashContents<T>(this IEnumerable<T> enumerable)
{
    int hash = 0x218A9B2C;
    foreach (var item in enumerable)
    {
        int thisHash = item.GetHashCode();
        //mix up the bits.
        hash = thisHash ^ ((hash << 5) + hash);
    }
    return hash;
}

This will give different hashcodes for {0,0} and {0,0,0}.

Answer 3

In .NET 4.0 arrays will support this via the IStructuralEquatable interface, but until that point you'll have to do it yourself I'm afraid.