[Info-vax] DCL Differences algorithm

[John Reagan]

"John Wallace" <johnwallace4 at yahoo.co.uk> wrote in message 
news:049953d1-118c-494e-be3d-437c6bc85f9d at l32g2000yqc.googlegroups.com...
Based on that experience, I'm not 100% convinced that VMS DIFF uses
the industry standard algorithm, but (a) I could be wrong (b) it may
not matter for your needs.


When I looked years ago, the code simply read records with RMS and used 
CH$EQL (or STR$COMPARE_CASE_BLIND or whatever the name is if you are 
ignoring case).  No funky 'hashing' or whatever.  As Fred said, all in 
BLISS, not too complicated.  Should be on the listing CDs for those of you 
with access.

Personally, for files with interesting differences, I used CMS DIFF instead 
of DCL DIFF.  I don't know what algorithm it uses, but it seems to not get 
as upset when I added a routine in the middle of a source module...  I'll 
guess that CMS DIFF just accesses the same difference engine used for 
REPLACE and edits to the CMS element files.

John