<?

php

 

// This function returns a date-type value based on the parameters passed
// Days are ISO standard: 1==Monday, 7==Sunday.
// specialDate(2, 1, 6, 2007) would return the second Monday of June 2007
// specialDate(-1, 5, 1, 2006) would return the LAST Friday of January 2006.

function specialDate($offset, $dayofweek, $month, $year)
{
if (!$offset)
throw new Exception('specialDate: Parameter 0 (offset) must not be zero');
if (($dayofweek < 1) or ($dayofweek > 7))
throw new Exception('specialDate: Parameter 1 (Day Of Week) must be 1..7');
if (($month < 1) or ($month > 12))
throw new Exception('specialDate: Parameter 2 (Month) must be 1..12');

// Invert the offset such that if it's >=4 it becomes -1, or <=-4 it becomes 1...
$offset = (abs($offset) >= 4) ? (($offset / abs($offset)) * -1) : $offset;

if ($offset > 0)
{
// Make a base time the first of the target month
$time = mktime(0, 0, 0, $month, 1, $year);
$move = 86400;
$weeks = --$offset * 604800;
} else {
// Make a base time the last of the target month
$time = mktime(0, 0, 0, $month + 1, 1, $year) - 86400;
$move = -86400;
$weeks = ++$offset * 604800;
}

// Now find the first matching DayOfWeek...
while (date('N', $time) <> $dayofweek) { $time += $move; }

// return the time, offset by weeks...
return $time + $weeks;
}
?>

<?

php

 
function specialDate($offset, $dayofweek, $month, $year, $forcefuture=false)
{
//error handling. this is generic do what you want.
if ((abs($offset) > 5) or ($offset == 0)) { return false; }
if (($dayofweek < 1) or ($dayofweek > 7)) { return false; }
if (($month < 1) or ($month > 12)) { return false; }

//make a base time assume the first of the month
$time = mktime(0,0,0,$month,1,$year);

$move = 1; //positive 1. just a single unit variable for plus or minus calcs

//we want something from the end of the month. so...
//increase 1 month and then decrease 1 day. puts you on last day of month
if ($offset < 0)
{
$time = DateAdd('m', 1, $time);
$time = DateAdd('d', -1, $time);
$move = -1; //going backward from end of month, so move is changed to negative
}

// Now find the first matching DayOFWeek...
while (date('N', $time) <> $dayofweek)
{
$time = DateAdd('d',$move,$time); //forward or back in time depending on neg/pos of $move
}

//determine how many weeks to add, $offset -1
//but since offset can be negative, we need to do funky math to reduce the offset value towards zero.
$time=DateAdd('w',($offset/abs($offset))*(abs($offset)-1),$time);

// Make sure that the offset or $weeks has not pushed me out of the target month...
//roll back or forward a week to get back into month. invert $move
if (date('m', $time) <> $month)
{
$time = DateAdd('w',-$move,$time);
}

//if we are forcing a future date, we recursively call this function with 1 year greater
        //if you dont care about enforcing future dates, you can chop out this part.
if (($forcefuture) and ($time < time()))
{
$time = specialDate($offset, $dayofweek, $month, $year+1, $forcefuture);
}

        //uh yea, return the timestamp of the specialdate
return $time;
}


//a Date shifting function that deals with leapyear and crazyness like that
function DateAdd($interval, $number, $time)
{
switch ($interval)
{
case 'y':
$timestamp = strtotime($number.' years', $time);
break;
case 'm':
$timestamp = strtotime($number.' months', $time);
break;
case 'd':
$timestamp = strtotime($number.' days', $time);
break;
case 'w':
$timestamp = strtotime($number.' weeks', $time);
break;
case 'h':
$timestamp = strtotime($number.' hours', $time);
break;
case 'n':
$timestamp = strtotime($number.' minutes', $time);
break;
case 's':
$timestamp = strtotime($number.' seconds', $time);
break;
}
return $timestamp;
}

?>