Sorry, but your problem does not imply a bug in PHP itself.  For a
list of more appropriate places to ask for help using PHP, please
visit http://www.php.net/support.php as this bug system is not the
appropriate forum for asking support questions. 

Thank you for your interest in PHP.

Neither mktime() nor gmmktime() understands arguments like "last Sunday" -- please go and re-read the documentation for those functions.  If you have any further questions, please ask them on the php-general list.

By substituting mktime() with strtotime() has the same problem.

On the strtotime page of the manual - one of the examples given states 'echo strtotime ("last Monday"), "\n";' - so I beleave my sytax is valid.

With my script ammended to be valid (as below) I think this is a bug.

function last_sunday() {
	return gmdate("Y-m-d", strtotime("Last Sunday"));
}
echo "Last Sunday is returned as: ".last_sunday();

With Daylight saving on the above = 2003-03-29
With Daylight saving off the above = 2003-03-30

I have also use the GMT keyword with strtotime(), but this fails also.

strtotime() uses the local timezone adjusted time unless you stick "GMT" at the end.  Try this:

echo date("H:i:s D M d, Y",strtotime("Last Sunday GMT"));
echo date("H:i:s D M d, Y",strtotime("Last Sunday"));

I am in PDT and right now this gives me:

16:00:00 Sat Mar 29, 2003
00:00:00 Sun Mar 30, 2003

which shows that strtotime adjusts for GMT correctly.  Midnight last Sunday in GMT was actually Saturday in my timezone as GMT is 8 hours ahead of me, so it gave me 4pm Saturday.  And when I pass it "Last Sunday" without the GMT, which means I am asking for midnight last sunday in my own timezone, I get exactly that.

Thanks for your reply- that failed also though, I tracked down the error - it seems that systems that have 'Automatically adjust Daylight Saving' switch on will return the wrong date.

I managed to get both exceptions to work using:

if(date("I") == 1){
 // Daylight Saving is ON
 return gmdate("Y-m-d", mktime("Last Sunday"));
} else {
 // Daylight Saving is OFF
 return date("Y-m-d", strtotime("Last Sunday"));
}

echo last_sunday();

Your code makes no sense.  mktime() does not understand "Last Sunday", so if this code fixed your problem, then you have a whole bunch of other problems.

Fair point - my solution should not work (but it does).

Here is more details of the problem:
using your code, I ran it with both exceptions.

1. Automatically adjust clock for daylight saving changes = ON
[code]
echo "with GMT: ".date("H:i:s D M d, Y",strtotime("Last Sunday GMT"));
echo "<br>without GMT: ".date("H:i:s D M d, Y",strtotime("Last Sunday"));
[/code]

returns:
with GMT: 23:00:00 Sat Mar 29, 2003
without: 23:00:00 Sat Mar 29, 2003

2. Automatically adjust clock for daylight saving changes = OFF
[code]
echo "with GMT: ".date("H:i:s D M d, Y",strtotime("Last Sunday GMT"));
echo "<br>without GMT: ".date("H:i:s D M d, Y",strtotime("Last Sunday"));
[/code]

returns:
with GMT: 00:00:00 Sun Mar 30, 2003
without: 00:00:00 Sun Mar 30, 2003

So you see the GMT does nothing!!!
And there is no way to have the same script run with both exceptions.

Am I the only one to have encountered this problem?