Here is another easy-to-solve problem that leads to more complex questions.

A standard DNS serial has the following syntax: YYYYMMDDVV, that is: the modification date in year-month-day format (four, two and two digits, respectively) and a two-digit version number. For example, the third version of today's map should be 2002062403.

Now suppose you have a script that updates your DNS maps: to update the serial your code should:

• retrieve today's year, month and day and merge them together, say with a sprintf; let's put it in $today;
• compare the serial $today, e.g.: with a pattern matching: if ($serial =~ /^$today/) {...;
• if the match doesn't succeed, then setting $serial is really easy: $newserial = $today."01" ;;
• if the match succeeds, it's easy again but a little more work is required: extract the last two chars of $serial and increment by one; no sweat: substr or a regexp are ok.

Solved this easy problem, one meditation came into my mind: having some data in this form: YYYYMMDDVV, what is the most efficient way to deserialize this data? I mean, among the many ways of doing the job:

• using substr repeatedly, once for datum;
• using a regexp like /^(\d{4})(\d{2})(\d{2})(\d{2})$/;
• doing weird karussels with pack (maybe);
• ...

which, in your opinion, could be the best way under several aspects (speed, memory consumption, cpu consumption, simplicity... choose your favourite :-)

Ciao!
--bronto

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