I have a question and can't find that specific answer.
In my application, my work year start on july 1 every years. So 52 weeks later, I start again on july first. What I want is a field that I enter let say week 32. I want to have the answer of what is the first day of that specified week and show it as date format. So in other words, if I put week 1 in the field, it will give me the result = July 1 and if I put Week 2 in the field, it will gives me july 8, etc. But I think that every year could change. So I need a calculation that will do this. Is it possible in php?
Tks for help
Seby
strtotime("July 1 2013 +".$monthNum." months");
something like this?
Related
I failed to find a proper solution to this issue. As you see in Example #3 in the PHP documentation, they state that one must beware when adding months using the DateInterval in DateTime::add.
There's not really any explanation for why the method's behavior is as such and what I can do to avoid this, which I find to be an error at first sight.
Anyone have some insight into this?
The issue is that each month can have a different number of days in them. The question is what you're doing when you want to increment a date by 1 month. Per the PHP documentation if you're on January 31st (or 30th) and you add 1 month, what is the expected behavior?
February only has 29 days in it. Do you want to be set to the last day of the month? You're generally safer incrementing by a set number of days if that's what you're looking for, or a static date based on the current date. Without knowing what you're trying to accomplish when you increment your month, it's tough to say how to watch for an error.
EDIT:
As someone mentions in the similar post commented by Mike B above, you probably want to do something where you (in pseudocode):
1) Use cal_days_in_month() for the next month and save that number to a variable x
2) If x >= current billing DOB, increment and be done
3) DateTime::modify('last day') (havent used this before but something along these lines) to set the date to the last date of the next month (set it to the 1st of the next month, then last day?)
Worth noting is that if you use the variable here as the new billing value, you'll wipe out your original value. I would save an extra DB value that's "first billing date" or just "billing_day_of_month" or something, and use that to figure out the day of month that you should be looking at
If your goal is to strictly increment by user-friendly months (thus, 3 months from January 21st should be April 21st), with the exception that shorter membership months get shortened (thus, 1 month from January 31st is February 28th/29th), then you only need to go back a few days if you crossed over into the next month:
function addMonths($date,$months) {
$orig_day = $date->format("d");
$date->modify("+".$months." months");
while ($date->format("d")<$orig_day && $date->format("d")<5)
$date->modify("-1 day");
}
$d = new DateTime("2000-01-31");
addMonths($d,1);
echo $d->format("Y-m-d"); // 2000-02-29
I have the following example of me subtracting the DateInterval from DateTimeImmutable
$dateA = new DateTimeImmutable('2016-06-30');
$dateB = new DateTimeImmutable('2016-05-31');
$dateInterval = new DateInterval('P3M');
// print 2016-03-30 as expected
echo $dateA->sub($dateInterval)->format('Y-m-d');
// print 2016-03-02 which i would expect 2016-02-29
echo $dateB->sub($dateInterval)->format('Y-m-d');
When I set the period to 'P8M' it works as expected. How it comes, it dosent works for february?
Ok, it's really simple (kind of). Each 'month' interval evaluates to the prior (or X number of prior) month's equivalent day. If there are more days in the current month, than the month being landed on, the excess overflows to the following month.
So if you have a date which is May 31, 2016 and want to subtract 3 month intervals, it will:
Go back 3 months (in the list of months, don't think days yet), resulting in 'February'
Then look for February 31st. This doesn't exist so bleed over to following month 2 days (2016 Febuary has 29 days, so 2 extra days)
Viola! March 2nd.
Go forward, lets say you're in May 31, 2016 and want to add one month
Go forward one month to June.
Look for June 31st, nope, 1 extra day, bleed over to July.
As expected, July 1st is the answer.
The lesson in this: Adding and Subtracting Month intervals sucks, is confusing, and can lead to non-intuitive results unless you've got your month calculation rosetta stone with you.
Explanation from the PHP Docs
Note:
Relative month values are calculated based on the length of months that they pass through. An example would be "+2 month 2011-11-30", which would produce "2012-01-30". This is due to November being 30 days in length, and December being 31 days in length, producing a total of 61 days.
I am trying to determine if a given date is the last day of that type (Sunday, Monday, Tuesday, etc.) in its month. For example, for March of 2016, the last Friday of the month is the 25th.
Please note I am not trying to figure out what the last day of the month is. Also, 'weekday' in the question refers to any of the 7 days, not just non-weekend days.
I am using excel and php as tags because I can work with either approach.
Just determine how close the given date is to the end of the month. For the given date in A1, use:
=IF(DATE(YEAR(A1),MONTH(A1)+1,0)-A1<7,TRUE,FALSE)
As the headline says, PHP's date("W") function gives back the calendar week (for the current day). Unfortunatly it gives back 52 or 53 for the first day(s) of most years. This is, in a simple thinking way, correct, but very annoying, as January 1st of 2012 is not calendar week 52, it's NOT a calendar week of the current year. Most calendars define this as week 0 or week 52 of the previous year.
This is very tricky when you group each day of the year by their calendar week: 1st of January 2012 and 31st of December 2012 are both put into the same calendar week group.
So my question is: Is there a (native) year-sensitive alternative to PHP's date("W") ?
EDIT: I think I wrote the first version of this question in a very unclear way, so this is my edit: I'm searching for a function that gives back the correct calendar week for the first day(s) of the year. PHP's date("W") gives back 52 for the 1st of January 2012, which is "wrong". It should be 0 or null. According to official sources, the first calendar week of a year starts on the first monday of the year. So, if the first day of a year is not a monday, it's not week 1 ! It's week 0. The wikipedia article says
If 1 January is on a Monday, Tuesday, Wednesday or Thursday, it is in week 01. If 1 January is on a Friday, Saturday or Sunday, it is in week 52 or 53 of the previous year.
This becomes tricky as the last days of the year are also in week 52/53. date("W") does not divide into current year and previous year.
This solution converts the excess of december to week 53 and everything in january prior to week 1 to week 0.
$w=(int)date('W');
$m=(int)date('n');
$w=$w==1?($m==12?53:1):($w>=51?($m==1?0:$w):$w);
echo "week $w in ".date('Y');
2013-12-31 ==> week 53 in 2013
2014-01-01 ==> week 1 in 2014
2015-12-31 ==> week 52 in 2015
2016-01-01 ==> week 0 in 2016
And a small test run, so you can see for yourself ;-)
$id=array(25,26,27,28,29,30,31,1,2,3,4,5,6,7,8);
for($iy=2013;$iy<2067;++$iy){foreach($id as $k=>$v){if($k<7){$im=12;}else{$im=1;}
if($k==7){++$iy;echo '====<br>';}$tme=strtotime("$im/$v/$iy");
echo date('d-m-Y',$tme),' * * ';
//THE ACTUAL CODE =================
$w=(int)date('W',$tme);
$m=(int)date('n',$tme);
$w=$w==1?($m==12?53:1):($w>=51?($m==1?0:$w):$w);
//THE ACTUAL CODE =================
echo '<b>WEEK: ',$w,' --- ','YEAR: ',date('Y',$tme),'</b><br>';}--$iy;
echo '----------------------------------<br>';}
Is there a (native) year-sensitive alternative to PHP's date("W") ?
No, there isn't.
According to official sources, the first calendar week of a year starts on the first monday of the year.
I'm not sure what official sources you're referring to.
PHP's date("W") returns the week number according to ISO 8601. As an international standard, ISO 8601 counts as one of possibly many "official sources". If its definition of week numbers doesn't fit your application, you're free to use anything else you like.
If you use a non-standard definition of "first week of the year", or if you use an official source that's not widely recognized, expect to have to write your own function to replace date("W"). (I'm pretty sure you'll need to write a function.)
The date 2012-01-01 was a Sunday. ISO 8601, Wikipedia, and php agree that the ISO week number for 2012-01-01 is 52.
ISO 8601 doesn't define a week 0.
So, if the first day of a year is not a monday, it's not week 1 !
Neither ISO nor Wikipedia say that. ISO 8601 defines week number 1 as the week that has the year's first Thursday in it. For 2012, the first Thursday was on Jan 5, so week number 1 was Jan 2 to Jan 8. 2012-01-01 was in the final week of the previous year, in terms of ISO weeks.
If you want something different, you can play with arithmetic, division, and so on. (Try dividing date("z") by 7, for example.) Or you can store that data in a database, and have your weeks any way you like.
If you're dealing with accounting periods, I'd almost certainly store that data in a table in a database. It's pretty easy to generate that kind of data with a spreadsheet.
The text of data in a table is much easier to audit than the text of a php function, no matter how simple that function is. And the data is certain to be the same for any program that accesses it, no matter what language it's written in. (So if your database someday has programs written in 5 different languages accessing it, you don't have to write, test, and maintain 5 different functions to get the week number.)
$d = new DateTime('first monday january '.date('Y'));
echo $d->format("W");
Google brought me here, and I wanted to post the following to help others like me...
I am in the US, and use DayPilot, and it works as follows:
Week starts on Sun, not Mon.
Jan 1st is always Week 1.
If Jan 1st is not a Sunday, Week 1 is less than 7 days.
This all makes a lot of since to me!
Here is my PHP function to copy that behavior:
function ProperWeekNum($inDate)
{$outNum = $inDate->format('W');
//Make week start on Sunday
if ($inDate->format('D') == 'Sun') {$outNum++;}
//Fix begining of year
if (($outNum >= 52) && ($inDate->format('M') == 'Jan')) {$outNum = 1;}
//Fix WEEK #1 is 1-day (Sat)
else //...without this 2022 was off by 1 all year
{$jan1st = new DateTime($inDate->format('Y').'-01-01');
if ($jan1st->format('D') == 'Sat') {$outNum++;}
}
//Return without leading zero
return ltrim($outNum, '0');
}
I use the function as follows, so when I click on DayPilot, my custom popup's Week # always matches DayPilot's Week #:
$weeknum = ProperWeekNum($startdate);
if ($weeknum != ProperWeekNum($enddate))
{$weeknum .= '-'.ProperWeekNum($enddate);}
Probably won't help the OP, but hopefully it helps someone.
I've seen lots of "Date" related questions here, however, I haven't been able to find one that calculates this:
I am trying to figure out the numerical value of a given date string. For example:
$date = "2010-09-01";
Given the date above, how might I be able to determine that this is the "1st" Wednesday of the month.
I know that: date("l", $date); will tell me that it's a Wednesday, but how do I determine if it's the 1st, 2nd, 3rd, or 4th Wednesday of the Month?
Any help on this would be great!
I think this gets you what you want:
$i = (int) (($day_of_month + 6) / 7);
where $day_of_month is from 1 to 31.
You just need a little bit of maths.
If the day of the month is < 8, then it's the first Wednesday. Or Friday. Or Monday. Or Saturday. So if it's between 7 and 15, then it's the second whatever. And so on. #konforce has posted the actual formula.