I have extracted a small portion of a calendar application I developed
recently to show some strange behavior with the date() function. When I
run this I get duplicate dates occasionally down the list. I'm seeing
11/4 twice for example. Sometimes dates are missing from the list. The
results change from day to day.

#!/usr/bin/env php
<?php

error_reporting( E_ALL );

define( 'SECONDS_IN_A_DAY', 60 * 60 * 24 );
define( 'LAST_SUNDAY', strtotime( 'last Sunday' ) );

echo 'SECONDS_IN_A_DAY = ' . SECONDS_IN_A_DAY . "\n";
echo 'LAST_SUNDAY = ' . LAST_SUNDAY . "\n";

for( $x = 0; $x < 365; $x++ )
{
$seconds = LAST_SUNDAY + ( SECONDS_IN_A_DAY * $x );
$date = date( 'n/j', $seconds );
echo "$seconds $date\n";
}

I get the same results with latest PHP4 and PHP5.


--
Greg Donald
Cyberfusion Consulting
http://cyberfusionconsulting.com/

> I'm seeing
> 11/4 twice for example. Sometimes dates are missing from the list. The
> results change from day to day.
>

That would be DST. The number of seconds per day changes on Nov. 4,
2007 in the US local time zones.