difference between dates problem

Mucello

I'm trying to get the number of days between two dates. The way I'm going about it is apparently wrong. Here is my code... an explanation of the problem follows.

$startRequestDate = 20030301;  // YearMonthDay
$endRequestDate = 20030501;

$difference = (strtotime($endRequestDate)-strtotime($startRequestDate))/86400;

echo $difference.' days';

If the dates being compared are relative close to each other, it works out fine. But with the example dates above, I get a decimal value for my difference. As you can see above, I'm comparing days not times so I shouldn't have a decimal for any calculated difference. My calculated difference should be a whole number of days if I'm not including times.

So my question is, why do I sometimes get decimal values between dates even though my days are just that-- days and not times. And then secondly, how can I fix this?

intenz

<?PHP
$date1 = mktime( 0, 0, 0, 10, 10, 2003 );
$date2 = mktime( 0, 0, 0, 9, 10, 2003 );
if( $date2 < $date1 )
        die( 'Not valid.' );
$equal = $date2 - $date1;
echo $equal / 60 / 60 / 24;
?>

Mucello

Thank you for the quick help. But I'm still getting the same problem with your code.

Check this out:

$date1 = mktime( 0, 0, 0, 1, 1, 2003 );
$date2 = mktime( 0, 0, 0, 9, 10, 2003 );
$equal = $date2 - $date1;
echo $equal / 60 / 60 / 24;

the echo above will give 251.95833333333 as the difference.

planetsim

try this

$start = mktime(0,0,0,5,1,2003);
$end = mktime(0,0,0,10,1,2003);
echo (($end-$start) / 60 / 60 / 24);

Mucello

planetsim-- thanks, I tinkered with your code some and get the same problem with some dates.

$start = mktime(0,0,0,3,1,2003);
$end = mktime(0,0,0,10,1,2003);
echo (($end-$start) / 60 / 60 / 24);

This will echo 213.95833333333 instead of a whole number of days. I don't understand why this isn't working.

intenz

Try this...

<?PHP
$date1 = mktime( 0, 0, 0, 1, 1, 2003 );
$date2 = mktime( 0, 0, 0, 9, 10, 2003 );
if( $date2 < $date1 )
        die( 'Not valid.' );
echo round( ( $date2 - $date1 ) / 60 / 60 / 24, 0 );
?>

Mucello

This clearly gives a whole number but only because it's rounding the calculation. I shouldn't have to round it off though.

intenz

Hehehe, this will work...

<?PHP
$date1 = mktime( 0, 0, 0, 1, 1, 2003 );
$date2 = mktime( 0, 0, 0, 9, 10, 2003 );
if( $date2 < $date1 )
        die( 'Not valid.' );
echo number_format( ( $date2 - $date1 ) / 60 / 60 / 24, 0, '', '' );
?>

Mucello

Well, in a sense the calculation is still be rounded. This is a way around the problem, not a solution to it. What if it should be rounded down instead of up? Then my calculation would be off by one day and that's no good.

intenz

Excuse me ?

intenz

numer_format() doesn't round.

Mucello

Originally posted by intenz
Excuse me ?

By using the number_format function, you specify the resulting number's precision. If you use your code without the number_format function, you get 251.95833333333 as the answer. Using number_format you get 252 as the answer. This does indeed give me a whole number, but only because it is forced to. That doesn't resolve the problem of the date calculation being inconsistent where sometimes its a whole number (as it should be) and other times its not.

intenz

Originally posted by Mucello
Thank you for the quick help. But I'm still getting the same problem with your code.

Check this out:
$date1 = mktime( 0, 0, 0, 1, 1, 2003 );
$date2 = mktime( 0, 0, 0, 9, 10, 2003 );
$equal = $date2 - $date1;
echo $equal / 60 / 60 / 24; 
the echo above will give 251.95833333333 as the difference. [/B]

I get 252.

Mucello

Check for yourself... the code exactly like I had it is at this URL:
http://www.nc-climate.ncsu.edu/test/test.php

I'm running PHP version 4.1.2

intenz

Uhh, update PHP. I have 4.3.3

crosbystillsnas

Originally posted by Mucello
Well, in a sense the calculation is still be rounded. This is a way around the problem, not a solution to it. What if it should be rounded down instead of up? Then my calculation would be off by one day and that's no good.

i think the problem is working with the time 00:00:00 of the day.
a stamp that is rounded down will be 1 day earlier as you mentioned, so maybe another time will provide loosing a hole day.
something like

$date1 = mktime( 10, 10, 10, 1, 1, 2003 );
$date2 = mktime( 10, 10, 10, 8, 12, 2003 );

if this timestamp is rounded, the stamp will still be of the same day.

Weedpacket

Originally posted by Mucello
That doesn't resolve the problem of the date calculation being inconsistent where sometimes its a whole number (as it should be) and other times its not.

Congratulations. You've just discovered Daylight Saving.