date() question

[warrior_rabbit]

What I'm trying to do is to check for and not exceed a 3-month peiod.
I have a YYYY-mm-dd date format via

$start=$startyear.-$startmonth.-$startdate;
$end=$endyear.-$endmonth.-$enddate;

Then I have:

echo $start; echo"<br />";
echo $end; echo"<br />";
echo date("m",$end); echo"<br />";
echo date("m",$start); echo"<br />";
echo date("m"+2,$start); echo"<br />";
if ( date("m",$end)>date("m"+2,$start))
	{
	echo "message saying only 3-month periods allowed";
        }

For something that starts/stops in July it echoes out:
2007-7-1
2007-7-31
12
12
2
and then the error message...

I'm on the right track (I think), but it seems that the last three echos are getting the "m" for the current month...and not the $start and $end. And of course I got the error message when I shouldn't have...

[Installer]

Try something like this:

$start = '2006-07-01';
$end = '2006-07-31';
$start_ts = strtotime($start);
$end_ts = strtotime($end);
echo $start . '<br />'; 
echo $end . '<br />';
echo date('m', $end_ts) . '<br />';
echo date('m', $start_ts) . '<br />';
$start_plus2_ts = strtotime('+2 months', $start_ts);
echo date('m', $start_plus2_ts) . '<br />';
if ($end_ts > $start_plus2_ts) {
    echo 'Message';
}

[warrior_rabbit]

Hmm. That works at least part of the time (better than mine already), but I'm still getting some weirdisms...

For instance I get

2006-10-1
2006-12-31
12
10
12

Sorry!

or

2006-6-1
2006-8-31
08
06
08

Sorry!

for reasons I can't understand. I mean, clearly the end_ts is not greater than the start_plus2_ts.

[Installer]

I don't know how you could possibly get those results. I get

2006-10-01
2006-12-21
etc.

and

2006-06-01
2006-08-21
etc.

Which is exactly what I would expect, assuming the logic in your first post is really what you want to do. And yes, 8-21 is more than two months after 6-1, and 12-31 is more than two months after 10-1.

[warrior_rabbit]

Yup, those are indeed the results I'm getting...

What I said I wanted to do was "check for and not exceed a 3-month peiod (sic)."

So if the user enters a start date of 2006-10-01 and an end date of 2006-12-31, it would be okay -- that's three months. (To me that means entire month of October, entire month of November, entire month of December -- but m+2 because October=10 and December=12.)

But if the user said start March 01 and end June 31, it would say no as that's four months.

I don't understand how 8-21 can be more than two months after 6/1, etc. I could change it to d instead of m and make it +90, but then I'd run into problems with months that end with 30 or 28...

I wish there was a first-day-of-month/last-day-of-month function that didn't require all this monkeying around and would take into account inconsistent month durations...Is there one? I looked and couldn't find anything.

[Weedpacket]

So the day doesn't matter? It's always going to be from the first of the month to the last of the month?

warrior rabbit wrote:

I don't understand how 8-21 can be more than two months after 6/1

1st of June to 30th of June (inclusive) - that's one month.
1st of July to 31st of July - that's two months.
1st of August to 21st of August - that's two months and twenty-one days: more than two months.

How do you count it? It's starting to sound like the day is irrelevant; as if "31 May 2006" to "1 July 2006" would count as "three months" - instead of one month and two days.

I'm reminded of this problem: you're building a wooden fence, ten metres long, that will have posts spaced one metre apart along its entire length. How many posts will you need?

[Installer]

I don't understand how 8-21 can be more than two months after 6/1...

Then I guess we have a difference of understanding. (From one to the other is 82 days. A month has at most 31 days...)

When I posted my code, I said

Try something like this:

All the ingredients are there. With some logical manipulation and some peeking into the manual you can get the results you want.

[warrior_rabbit]

How do I count months? As I said before, the way I see it is a start date of 2006-10-01 and an end date of 2006-12-31 is three months. (The entire month of October, entire month of November, entire month of December -- but m+2 because October=10 and December=12.)

It's always going to be the start date of the 1st for the month they choose and an end date of the 31st, 30th, or 28th (as appropriate) for whatever month they pick. But not allowing a 4th month is what I'm shooting for.

The manual is not much help to me. I have some PHP books which explain things better, but I think this is too specific for them.

I did search the date/time functions on php.net for a first-of-month/last-of-month thing, but I didn't find anything.

And I have wondered how Nov 1-Jan 31 would work re the is end_ts>start_ts...would I have to use m and Y in the formula for it to recognize that 1 is greater than 11?

[Installer]

if (date('Ym', $end_ts) > date('Ym', $start_plus2_ts)) { 
    echo 'Message'; 
}

[suntra]

I wrote this maybe one or two years ago... don't have time translating so have fun ! (have an exam ou 30 min !)

<?
 $arrNZAU_Jours_Mois	= array (
			1	=> 31,
			2	=> 28,
			3	=> 31,
			4	=> 30,
			5	=> 31,
			6	=> 30,
			7	=> 31,
			8	=> 31,
			9	=> 30,
			10	=> 31,
			11	=> 30,
			12	=> 31
		);
 function NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee) {
	$intTotal_Jours	= $GLOBALS['arrNZAU_Jours_Mois'][$intMois];
	$intTotal_Jours	+= ((($intMois == 2) && !($intAnnee % 4)) ? 1 : 0);
	return $intTotal_Jours;
 }
 function NZAU_RETOURNER_DATE_MODIFIER($strDate, $intDifference, $strMode) {
	$intAnnee		= intval(substr($strDate, 0, 4));
	$intMois		= intval(substr($strDate, 4, 2));
	$intJour		= intval(substr($strDate, 6, 2));
	$intAnnee_Difference	= (($strMode == 'A') ? $intDifference : 0);
	$intMois_Difference	= (($strMode == 'M') ? $intDifference : 0);
	$intJour_Difference	= (($strMode == 'J') ? $intDifference : 0);
	if($intJour_Difference > 0) {
		$intJour1	= $intJour + $intJour_Difference;
		while($intJour1 > NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee)) {
			$intJour1	-= NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee);
			$intMois++;
			if($intMois > 12) {
				$intMois	= 1;
				$intAnnee++;
			}
		}
		$intJour	= $intJour1;
	} elseif($intJour_Difference < 0) {
		$intJour1	= $intJour - abs($intJour_Difference);
		while($intJour1 < 1) {
			$intMois--;
			if($intMois < 1) {
				$intMois	= 12;
				$intAnnee--;
			}
			$intJour1	+= NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee);
		}
		$intJour	= $intJour1;
	}
	if($intMois_Difference > 0) {
		$intMois1	= $intMois + $intMois_Difference;
		$intAnnee	+= floor($intMois1 / 12);
		$intMois	= $intMois1 % 12;
		if($intJour > NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee)) {
			$intJour	= NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee);
		}
	} elseif($intMois_Difference < 0) {
		$intMois1	= $intMois - abs($intMois_Difference);
		$intAnnee	-= floor($intMois1 / 12);
		$intMois	= $intMois1 % 12;
		if($intJour > NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee)) {
			$intJour	= NZAU_RETOURNER_MOIS_TOTAL_JOURS($intMois, $intAnnee);
		}
	}
	$intAnnee	+= $intAnnee_Difference;
	return NZAU_RETOURNER_DATE($intJour, $intMois, $intAnnee);
 }
 function NZAU_RETOURNER_DATE_JJMMAAAA($strDate) {
	$strAnnee	= substr($strDate, 0, 4);
	$strMois	= substr($strDate, 4, 2);
	$strJour	= substr($strDate, 6, 2);
	return sprintf('%s/%s/%s', $strJour, $strMois, $strAnnee);
 }
 function NZAU_RETOURNER_DATE($intJour, $intMois, $intAnnee) {
	$intJour	= abs(intval($intJour));
	$intMois	= abs(intval($intMois));
	$intAnnee	= abs(intval($intAnnee));
	if($intJour == 0 || $intMois == 0 || $intAnnee == 0) {
		return false;
	} else {
		$strJour	= (($intJour < 10) ? '0' : '') . strval($intJour);
		$strMois	= (($intMois < 10) ? '0' : '') . strval($intMois);
		$intAnnee	+= (($intAnnee < 100) ? 2000 : (($intAnnee < 1000) ? 1900 : 0));
		$strAnnee	= strval($intAnnee);
		return sprintf('%s%s%s', $strAnnee, $strMois, $strJour);
	}
 }
?>

[Weedpacket]

warrior rabbit wrote:

(From one to the other is 82 days. A month has at most 31 days...)

Well, by that standard, 82 days is still more than two months (which can be at most 62 days).

How do I count months? As I said before, the way I see it is a start date of 2006-10-01 and an end date of 2006-12-31 is three months. (The entire month of October, entire month of November, entire month of December -- but m+2 because October=10 and December=12.)

It's a good idea to try and come up with a rule that will work for any two dates, not just one specific example. Without such a rule you'll have no hope expressing it in code.

But by your description ("It's always going to be the start date of the 1st for the month they choose and an end date of the 31st, 30th, or 28th (as appropriate) for whatever month they pick."), the days are totally irrelevant. You're counting entire calendar months, and the fact that some have 30 days while others have 29 is no more going to affect how you count them than the fact that some have the letter 'r' in their name and others have the letter 'y'.

$start_month = 5; // Something between 1 and 12 inclusive.
$end_month = 8; // ditto
if($end_month<$start_month) // in case we span the new year.
    $end_month = $end_month+12;

$duration = $end_month-$start_month+1;

If necessary, you could check the year as well, to make sure they're not trying for fourteen months. The reason for the "+1" in the last line can be answered by answering my question about the fence.