First fof all, it's Perl, not PERL.

The simple idea is to create a hash containg all the new IDs as keys and then iterating over the old list and all IDs that arent found in the hash are the IDs of the missing students.

That is probably good enough for doing it once. More advanced would be to store all new IDs in an array, where the IDs are values. The iteration over the old IDs would then use a fast search (binary) to find missing IDs. I only call this more advanced because it doesn't invlolve hashing, although hashing is probably the most efficient method here...hmm

--
http://fruiture.de

In reply to Re: file comparison by fruiture
in thread file comparison by gasky

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