From: Brian Candler <b.candler@...>
Date: 2011-02-07T04:51:17+09:00
Subject: Re: looking for math

soldier.coder wrote in post #979906:
> I'm looking for code that will do some operation on a file and give me
> a number that is unique to that file.  if I happen to come across same
> file somewhere else and the contents are the same, the same number
> should be produced.
>
> First what is that called

It's called a "cryptographic hash".
http://en.wikipedia.org/wiki/Cryptographic_hash_function

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