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Message from discussion Hash??? What ARE the latest hot-shot methods?
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Dan Bernstein  
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 More options Dec 5 1990, 5:52 pm
Newsgroups: comp.lang.c
From: brns...@kramden.acf.nyu.edu (Dan Bernstein)
Date: 5 Dec 90 00:37:28 GMT
Local: Tues, Dec 4 1990 7:37 pm
Subject: Re: Hash??? What ARE the latest hot-shot methods?
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In article <1990Dec4.142017.12...@batcomputer.tn.cornell.edu> ly...@batcomputer.tn.cornell.edu (Tim Lynch) writes:

> Thanks for the reference.  Can someone recommend a book that does go into
> all the latest "hot-shot" methods?

Have there been any fundamentally new hashing methods in the last twenty
years? The only one I know of is Pearson's.

What are you really looking for? There are lots of string functions that
are both fast and, in practice, better than random hashing. These days I
start from h = 5381, and set h = h << 5 + h + c mod any power of 2 for
each new character c. Apparently Chris Torek prefers a multiplier of 31:
h << 5 - h + c. These are reliable and extremely fast. You can make them
even faster if you want to hash an entire string at once: just
precompute powers of 31 or 33, etc.

---Dan


 
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