FAQ 4.14 How can I compare two dates and find the difference?

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4.14: How can I compare two dates and find the difference?

    (contributed by brian d foy)

    You could just store all your dates as a number and then subtract. Life
    isn't always that simple though.

    The "Time::Piece" module, which comes with Perl, replaces "localtime"
    with a version that returns an object. It also overloads the comparison
    operators so you can compare them directly:

            use Time::Piece;
            my $date1 = localtime( $some_time );
            my $date2 = localtime( $some_other_time );
            if( $date1 < $date2 ) {
                    print "The date was in the past\n";

    You can also get differences with a subtraction, which returns a
    "Time::Seconds" object:

            my $diff = $date1 - $date2;
            print "The difference is ", $date_diff->days, " days\n";

    If you want to work with formatted dates, the "Date::Manip",
    "Date::Calc", or "DateTime" modules can help you.


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