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Re: Old Timers ?? [message #22297]

Thu, 02 November 2000 09:55

John-David T. Smith is currently offline

John-David T. Smith
Messages: 384
Registered: January 2000

Senior Member

Paul van Delst wrote:
> O.k., following the advice that "he who asks a question is a fool for 5 minutes, he who
> does not ask a question is a fool forever" I have to ask:
>
> What is a hash?
>
> I have seen the term used before regarding string searches but, being a mostly fortran
> number crunchy type programmer, I've never been one for searching through strings and what
> not.

Also known as a "named associative list", or "associative array", hashes
(or "hash tables") are specialized lookup tables. You can think of them
as arrays indexed, not with numeric indices, but with string values (or
even other data types for some languages). In the example in this
thread, a hash element would exist for each keyword... e.g.

hash["file ID"]="test"
hash["otherkeyword"]=12.22

etc. Hashes are like infinitely malleable structures, which is why they
are so nice. They are somewhat complicated to make (not for us, but for
the language designers), but easy and fast to use. Here's a link I
found: http://www.math.utah.edu/~beebe/software/hash/hash.html.

Hashes are built into Perl, which is why they are so popular these days,
I think (no offense to the lisp programmers out there).

JD

--
J.D. Smith | WORK: (607) 255-6263
Cornell Dept. of Astronomy | (607) 255-5842
304 Space Sciences Bldg. | FAX: (607) 255-5875
Ithaca, NY 14853 |

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		Re: Old Timers ?? By: John-David T. Smith on Thu, 02 November 2000 09:55
		Re: Old Timers ?? By: Paul van Delst on Thu, 02 November 2000 08:31
		Re: Old Timers ?? By: John-David T. Smith on Thu, 02 November 2000 08:01

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