Question

A simple code to print a date

$first_date = 1319493600;
$last_date = 1320184800;

$testDate = $first_date;


while ($testDate<=$last_date)
{
    echo strftime("%a", $testDate).' '. strftime("%d", $testDate).' '.strftime("%b", $testDate).'<br>';
    $testDate += 86400;
}

Yes this simple script fails me as you see below

Tue 25 Oct
Wed 26 Oct
Thu 27 Oct
Fri 28 Oct
Sat 29 Oct
Sun 30 Oct <----Error
Sun 30 Oct <----Error
Mon 31 Oct
Tue 01 Nov

Anyone has any idea why?

Answer 1

This is, in fact, the reason why you should never increment the day by adding 24 hours to the timestamp. Chances are that you are in a timezone that observes daylight saving time and the last Sunday of October is not 24 hours long.

You can confirm this by adding echo strftime("%r %x", $testDate); inside the loop. (Also note that you can use multiple modifiers in strftime() so you don’t have to concatenate them: strftime("%a %d %b", $testDate);.)

Always use date functions like strtotime() or mktime() to increment the date.