[SOLVED] Need to calculate a Firefighters Schedule in PHP

[snowman2344]

I need to calculate the following schedule in php. What I need out of the script is what shift is working “today” E.G. $shift = d;.  There are 4 shifts working 24hr days starting at 7 am. The days rotate on 28 day cycles. E.G.  ‘C shift’  is working on July 1 (Sunday) the next Sunday they work is the 29th. I found some code that works with 3 shifts on a different cycle but I have 4 shifts.

 

  $referencePoint = mktime(7, 0, 0, 9, 11, 2004);   // Sept 11, 2004 at 7AM started an A Shift.
  $now = time();
  
  // Next we need to know how many seconds since the start of the last A Shift.
  // First we compute how many 3 days cycles since the reference point then
  // subtract that number.
  
  $difference = ($now - $referencePoint);
  $cycles = floor($difference / (60 * 60 * 24 * 3));
  $sinceReference = ($difference - ($cycles * 60 * 60 * 24 * 3));

  if ($sinceReference < 60 * 60 * 25) {  // Before the start of the 25th hour it's A Shift.
    $shift = "A";
    }
  
  elseif ($sinceReference < 60 * 60 * 49) {  // Else before the start of the 49th hour it's B Shift.
    $shift = "B";
    }
  
  else {
    $shift = "C";  // Else it's C Shift.
    }

 

[sasa]

try

<?php
$start_date = '7/1/2007';
$shift_cycle = array('C',
				 'A','B','C','A','D','C','D',
				 'B','C','D','B','A','D','A',
				 'C','D','A','C','B','A','B',
				 'D','A','B','D','C','B');
$today = date('m/d/y');
//$today = '12/29/2007'; //for testing
echo 'Shift is ', $s = $shift_cycle[((strtotime($today) - strtotime($start_date))/(86400))%28];
?>

[snowman2344]

That seems to work great

 

thanks

[snowman2344]

Just so i can learn from this what does the %28 do?? ???

[teng84]

% is  modulo (remainer)

[snowman2344]

Guess is missed that in junior school.??