Path: utzoo!mnetor!uunet!husc6!sri-unix!quintus!ok
From: ok@quintus.UUCP (Richard A. O'Keefe)
Newsgroups: comp.unix.questions
Subject: Re: Unix diff(1) algorithm
Message-ID: <532@cresswell.quintus.UUCP>
Date: 14 Jan 88 03:47:19 GMT
References: <11229@brl-adm.ARPA> <7068@brl-smoke.ARPA>
Organization: Quintus Computer Systems, Mountain View, CA
Lines: 19
Summary: PD diff available

There is a public domain version of diff(1) coded in C that you can
get from a comp.sources.misc archive.

	Subject: v02i001: Public domain diff
	Keywords: diff
	X-Archive: comp.sources.misc/8801/1
	Comp.sources.misc: Volume 2, Issue 1
	Archive-Name: pd-diff
	Submitted-By: blarson@skat.usc.edu (Bob Larson)

I believe it started life as part of the DECUS goodies.  I have it,
but haven't installed it yet.

The trouble with diff(1) is that it assumes that the only changes are
insertions and deletions.  So if you swap two functions, it reports
two changes.  The method which appeared in CACM can spot moves as well
as insertions and deletions.  I have a Pascal implementation of that
method, which works well enough to use but not well enough to publish.
There are some things you need that the article didn't explain.