How do I find the number of days between two dates?

You want to know how many days until a certain date, or how long between two dates. Perl has many different modules to handles dates.

Time::Local

The following program uses the Time::Local module to determine my age in seconds:

    #!/usr/bin/perl
    use strict;
    use warnings;
    use Time::Local;

    my @today = localtime();
    my $time = timelocal(@today);

    my @birthday = (0, 54, 23, 3, 4, 1980);
    my $birthtime = timelocal(@birthday);

    print "My age in seconds = " . ($time - $birthtime) . "\n";

    exit 0;

The output of this program is something like:

    My age in seconds = 751538646

Date::Calc

The Date::Calc module is a very powerful module that allows many different types of date calculations. The follow example calculates how old I am in days:

    #!/usr/bin/perl
    use strict;
    use warnings;
    use Date::Calc qw(Delta_Days);

    my @today = (localtime)[5,4,3];
    $today[0] += 1900;

    my @birthday = (1980, 4, 3);

    my $days = Delta_Days(@birthday, @today);

    print "I am $days days old\n";

    exit 0;

The output of this example is something like:

    I am 8698 days old

Date::Manip