php supports c style date functions. You can add or substract date-periods with English-language style phrases via the strtotime function. examples...
$Today=date('y:m:d');
// add 3 days to date
$NewDate=Date('y:m:d', strtotime('+3 days'));
// subtract 3 days from date
$NewDate=Date('y:m:d', strtotime('-3 days'));
// PHP returns last sunday's date
$NewDate=Date('y:m:d', strtotime('Last Sunday'));
// One week from last sunday
$NewDate=Date('y:m:d', strtotime('+7 days Last Sunday'));
or
<select id="date_list" class="form-control" style="width:100%;">
<?php
$max_dates = 15;
$countDates = 0;
while ($countDates < $max_dates) {
$NewDate=Date('F d, Y', strtotime("+".$countDates." days"));
echo "<option>" . $NewDate . "</option>";
$countDates += 1;
}
?>
using the strtotime() function is very expensive and would be massive overkill if you just want to add a couple of days.
Sounds like premature optimization. If it's not in a time-critical piece of code, and we have no reason to think it is, burning a few milliseconds is nothing compared to the cost of programmer time.