#!/bin/perl
#    This is something I cobbled together one day to keep track of dates.
#  Given a Saturday's date, I wanted to be able to get next Saturday's date.
#  (See my first attempt in date1.pl)
#
#  This is improved because I wanted to maintain a human-readable date
#  value, e.g. 12/07/2001, not the number of seconds, 1007798400.
#  This makes it easy for a person to maintain the state file and gives
#  us something we can easily use for a directory name.

$mm=12; $dd=7;  $yyyy=2001;     # A starting point, 12/07/2001.
$mm=3;  $dd=24; $yyyy=2001;     #                or 03/24/2001.

use Time::Local;        # Need this to get timelocal defined.

@z2=('00' .. '32');     # A handy array to get zero-padding on my mm/dd;
                        # See Perl book on page 104.

print "         Starting with $z2[$mm]/$z2[$dd]/$yyyy,\n";

for (1..60) {     # Loop through a year to prove this works across
                  # Daylight Savings time, New Year's, and Leap Day transitions.
                  # Note the interesting way of saying, do something 60 times.
                  # Inside this loop, $_ is our loop index, ranging from 1 to 60.

   # Note that 608400 seconds = 1 week + 1 hour.  This handles the fall
   # Daylight Savings Time transition correctly, and since we don't care
   # about the time of day, we can get away with this "sloppiness".
   $number_seconds = timelocal(0,0,0,$dd,$mm-1,$yyyy-1900) + 608400;

   # A cute way to extract just a slice of what localtime returns.
   ($dd,$mm,$yyyy)=(localtime($number_seconds))[3..5];

   $mm++; $yyyy+=1900;     # Adjust for localtime's idiosyncracies.

   print "one more week makes it $z2[$mm]/$z2[$dd]/$yyyy,\n";
}