Adding days to a timestamp

Question

Giving a starting date, I\'m adding four times seven days to get 5 different dates separated exactly a week each one.

//$date = \'28-10-2010\';
$timestamp = mkti         


        

Answer 1

Never use math like 60*60*24*7 to add/subtract days (because of daylight time saving), use strtotime or mktime instead:

$timestamp = strtotime('+7 days', $timestamp);

// Or something like this (it's OK to have day parameter <= 0 or > 31)
$timestamp = mktime(0, 0, 0, $month, $day + 7, $year);

Your example will be more obvious if you'll output time as well:

$timestamp = mktime(0, 0, 0, 10, 28, 2010);
echo date('Y-m-d H:i:s', $timestamp) . "\n";

$timestamp += 60*60*24*7;
echo date('Y-m-d H:i:s', $timestamp) . "\n";

Output:

2010-10-28 00:00:00
2010-11-03 23:00:00

Here you have 2010-11-03 23:00:00 instead of 2010-11-04 00:00:00 because one of the days (31 Oct) is 25 hours long instead of 24.