How do you implement GetHashCode() on objects? [duplicate]

Question

Duplicate: What is the best algorithm for an overridden System.Object.GetHashCode?

If you've written an object with a variety of data-members, how do you intelligently implement GetHashCode()?

One developer told me he just XORs (^ operator) the Hash of relevant data-fields, but I am unconvinced this is a "best-practices" implementation.

If I had my way, there would be functions Object.CombineHashes(Object[]), and/or Object.CombineHashes(int[]) to help intelligently build hashes of complex objects.

How would you write these functions?

Nice find, @Gortok. I voted to close.

Michael Haren
– Michael Haren

2009-01-14 01:16:29 +00:00
Commented Jan 14, 2009 at 1:16 — Michael Haren
– Michael Haren, Commented Jan 14, 2009 at 1:16

Michael Haren · Accepted Answer · 2009-01-14 01:15:05Z

1

I did a quick and dirty implementation of a bunch of members by concatenating them with pipes and then getting the hascode of that:

(Member1.ToString() + "|" + Member2.ToString()).GetHasCode();

In my case, I know that I won't ever have pipes in the members so I knew the results would be pretty good.

Actually, in my case I implemented ToString for debugging purposes so I just used that:

this.ToString().GetHashCode();

Xors is another approach I've often seen.

edited Jan 14, 2009 at 1:15

answered Jan 14, 2009 at 1:09

Michael Haren

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1 Comment

abelenky Over a year ago

This approach has serious performance implications. Considering where GetHashCode is used, this seems effective, but unwise.

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