What have you tried? What worked? What didn't? See How do I post a question effectively?.

First, I would suggest using ISO_8601 as your date format, since this sorts easily. For the date arithmetic, I would suggest using a module to do the math, since dealing with days-of-month variation is an unnecessary headache. DateTime is a common choice for that. You could implement the looping component using two nested loops, a la: 

for my $time1 (sort keys %hash) {
    for my $time2 (sort keys %hash) {
        next if $time2 < $time1;
        ... # And do the math
    }
}

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#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: Hash Math by kennethk
in thread Hash Math by marlowvoltron

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