kdiff3 is quite a good one

http://kdiff3.sourceforge.net/

You can put a preprocessor which runs before diffing, so with a grep command
you can filter out comments...

(also exists on linux)

Tamas


On 12/18/06, Mike Hord <mike.hord@gmail.com> wrote:
>
> Does anyone know a good free file compare utility for ASCII files?
>
> The feature that I really need is a specifiable comment character-
> i.e., "lines that start with ' should be excluded from comparison
> until a new line is reached".  I'm recommenting and refactoring
> old code, and I need a way to see what's changed in type 1
> between versions A and B so that I can upgrade types 2 and 3
> from their current version to their next version.
>
> What a pain.
>
> Mike H.
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