From: "soldier.coder" <geekprogrammer.ed@...>
Date: 2011-02-07T02:30:19+09:00
Subject: looking for math

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, and anyplace i can see code that does that?