# date/time calculations: calculating exact difference

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Kimmo Laine wrote:

Unless next_page.php generates PHP, the script with this include will
only get HTML.

next_page.php

<?php
if (isset(\$_GET['foo'])) {
echo '<?php echo \$_GET[\'foo\']; ?>';
} else {
echo '<?php echo \'Not available\'; ?>';
}

--

## Re: date/time calculations: calculating exact difference

Hans Gruber wrote:

Look into the date functions.  There are functions in there to tell you
how many days are in the current month.  Even if you wanted to do this
by hand you could create an array with each month and how many days it
has and check for a leap year.

Then use the date function to work with these.... It will work, but to
get it in your exact format might be a bit of work.

Mike

## Re: date/time calculations: calculating exact difference

Kimmo Laine wrote:

Unless next_page.php generates PHP, the script with this include will
only get HTML.

next_page.php

<?php
if (isset(\$_GET['foo'])) {
echo '<?php echo \$_GET[\'foo\']; ?>';
} else {
echo '<?php echo \'Not available\'; ?>';
}

--

## Re: date/time calculations: calculating exact difference

from Hans Gruber contained the following:

It's easy as you say, to convert seconds into minutes hours days and
weeks. But if you said months what would you mean?  Often the secret to
coding something is the correct identification of the problem.

Let's say I want to work out how many months it is till my next birthday
(March 5th).  What I'd probably do is ignore the month length difference
and count up.  It's May 16th today and so it's 9 months till February
16th.  Then it's 13 days till my birthday.

If that's the way you want to work it out then you have your logic.  I'm
not going to code it but I think I'd be looking carefully at mktime() if
I was.

--
Geoff Berrow (put thecat out to email)
It's only Usenet, no one dies.
My opinions, not the committee's, mine.
Simple RFDs http://www.ckdog.co.uk/rfdmaker /

## Re: date/time calculations: calculating exact difference

On Mon, 16 May 2005 07:54:48 +0100, Geoff Berrow

If your birthday was 30 June and today was 31 May would that be 1
month or just 30 days until your birthday?

Although if you decided the answer was "1 month", be aware you'd get
the same answer on 30 May.

There isn't really a "correct" answer, but the OP should consider
these edge cases.

However, it depends what data represents and how the user will use it.
If long differences are shown to a lower resolution, this anomaly may
not matter. If the time difference is several months, the user may not
be interested in the value down to the minute and second.

For example:

DIFFERENCE :- WHAT TO SHOW

< 60 days :- days only.
< 7 days :- days, hours.
< 1 day :- hours, minutes.
< 6 hours :- hours, minutes, seconds.

--
David ( @priz.co.uk )