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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