날짜 연산 함수

function fnc_date_calc($this_date,$num_days){
  
   $my_time = strtotime ($this_date); //converts date string to UNIX timestamp
   $timestamp = $my_time + ($num_days * 86400); //calculates # of days passed ($num_days) * # seconds in a day (86400)
     $return_date = date("Y/m/d",$timestamp);  //puts the UNIX timestamp back into string format
  
   return $return_date;//exit function and return string
}//end of function

$date_to_test = "2006/08/11";
$days_to_add = 7;

$past_date = fnc_date_calc($date_to_test,(($days_to_add)*-1));
$future_date = fnc_date_calc($date_to_test,$days_to_add);

echo "Test Date is:  ".$date_to_test;
echo "<br>";
echo "Number of days to Calculate is: ".$days_to_add;
echo "<br>";
echo "Past date is:  ".$past_date;
echo "<br>";
echo "Future date is: ".$future_date;