Bug #63740 [Com]: strtotime seems to use both sunday and monday as start of week

From: Date: Mon, 13 Jul 2015 09:51:55 +0000
Subject: Bug #63740 [Com]: strtotime seems to use both sunday and monday as start of week
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=63740&edit=1

 ID:                 63740
 Comment by:         mrtreinis at gmail dot com
 Reported by:        salmanarshad2000 at yahoo dot com
 Summary:            strtotime seems to use both sunday and monday as
                     start of week
 Status:             Open
 Type:               Bug
 Package:            Date/time related
 PHP Version:        5.4.9
 Block user comment: N
 Private report:     N

 New Comment:

This is a rather horrible bug, bumping for pressure. 

Another test sample: 

(date)->modify('Monday this week')

2015-07-06: 2015-07-06 // Mo - Mo
2015-07-07: 2015-07-06 // Tu - Mo
2015-07-08: 2015-07-06 // We - Mo
2015-07-09: 2015-07-06 // Th - Mo
2015-07-10: 2015-07-06 // Fr - Mo
2015-07-11: 2015-07-06 // Sa - Mo
2015-07-12: 2015-07-13 // Su - Mo next week???!!!


Previous Comments:
------------------------------------------------------------------------
[2014-10-27 09:14:10] ca at noyo dot dk

I agree with salmanarshad2000, something's wrong here.

googleguy@php.net explains how "this week" is normalized:

"Sat 2012-12-08" is normalized to "Mon 2012-12-03"
"Sun 2012-12-09" is normalized to "Mon 2012-12-10". 

This seems wrong, the two days are in the same week. They should both normalize to "Mon
2012-12-03".

------------------------------------------------------------------------
[2013-02-11 17:34:54] timakeeling at gmail dot com

Related To: Bug #64181

------------------------------------------------------------------------
[2013-01-24 08:31:06] salmanarshad2000 at yahoo dot com

The latter part which explains that "Sunday this week" is evaluated as (i) this week (ii)
very next sunday is well explained and understandable. 

The former part which mentions that "time argument of strtotime() such as this week [is
interpreted as] a week period of Monday through Sunday" is still 
confusing. It does return a Monday but does it return the correct Monday?

/* when today is  */                                                                        /* this
week is   */
/* Mon 2012-12-03 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-03"))); /* Mon 2012-12-03 */
/* Tue 2012-12-04 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-04"))); /* Mon 2012-12-03 */
/* Wed 2012-12-05 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-05"))); /* Mon 2012-12-03 */
/* Thu 2012-12-06 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-06"))); /* Mon 2012-12-03 */
/* Fri 2012-12-07 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-07"))); /* Mon 2012-12-03 */
/* Sat 2012-12-08 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-08"))); /* Mon 2012-12-03 */
/* Sun 2012-12-09 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-09"))); /* Mon 2012-12-10 */

/* Mon 2012-12-10 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-10"))); /* Mon 2012-12-10 */
/* Tue 2012-12-11 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-11"))); /* Mon 2012-12-10 */
/* Wed 2012-12-12 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-12"))); /* Mon 2012-12-10 */
/* Thu 2012-12-13 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-13"))); /* Mon 2012-12-10 */
/* Fri 2012-12-14 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-14"))); /* Mon 2012-12-10 */
/* Sat 2012-12-15 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-15"))); /* Mon 2012-12-10 */
/* Sun 2012-12-16 */ echo date("D Y-m-d", strtotime("this week",
strtotime("2012-12-16"))); /* Mon 2012-12-17 */

You can see that the output changes on Sundays, not Mondays. Expected:

"this week" on Sun 2012-12-09 should return the week starting Mon 2012-12-03 (ending on
Sun 2012-12-09 inclusive)
"this week" on Sun 2012-12-16 should return the week starting Mon 2012-12-10 (ending on
Sun 2012-12-16 inclusive)

Actual:

this week on Sun 2012-12-09 returns the week starting _coming_ Mon 2012-12-10 
this week on Sun 2012-12-16 returns the week starting _coming_ Mon 2012-12-17

------------------------------------------------------------------------
[2013-01-23 16:04:21] googleguy@php.net

I've actually recently updated the documentation about strtotime in regard to this very 
behavior. See Bug #52143.

The problem is that prior to PHP 5.3.0 the relative time formats "this week", "next
week", 
"previous week" were taken to mean a 7 day period relative to the current time. However, 
the behavior was changed in PHP 5.3.0 to be interpreted as "a week period of Monday 
through Sunday". This is noted in the documentation for strtotime in the changelog section 
since last week.

http://php.net/manual/en/function.strtotime.php#refsect1-function.strtotime-changelog

We can see this behavior more clearly from the following code...


var_dump(date("D Y-m-d", strtotime("this week",
strtotime("2012-12-08"))));
string(14) "Mon 2012-12-03"

var_dump(date("D Y-m-d", strtotime("this week",
strtotime("2012-12-09"))));
string(14) "Mon 2012-12-10"


Here what you'll notice is that "this week" always starts on a Monday. Now, when you
want 
make that format relative to a particular day of the week, let's say Sunday...

var_dump(date("D Y-m-d", strtotime("Sunday this week",
strtotime("2012-12-08"))));
string(14) "Sun 2012-12-09"

var_dump(date("D Y-m-d", strtotime("Sunday this week",
strtotime("2012-12-09"))));
string(14) "Sun 2012-12-16"


What you should notice is that "this week" is first normalized to "Mon
2012-12-03" and 
"Mon 2012-12-10", respectively. Then the day is moved up to the first "Sunday"
of that 
week (i.e. +6 days on each week).

This might sounds a little confusing because if you are expecting the week to begin on a 
Sunday and end on a Saturday then you would assume that "Sunday this week" would mean 
"2012-12-09" where the date is "2012-12-09" and the day is a Sunday. But
that's not the 
case. "this week" means Monday of the current week and then move up until the very next 
Sunday. So if today is Sunday, we don't get today's date when we try "Sunday this
week".

------------------------------------------------------------------------
[2012-12-11 15:18:40] salmanarshad2000 at yahoo dot com

Description:
------------
Weeks start on Sunday or Monday. However, in this regard:

1) strtotime behavior is not documented.
2) strtotime produces inconsistent results when "this week" is used.

Sample dates from month of December 2012 used the the test script:

Mon 2012-12-03
Tue 2012-12-04
Wed 2012-12-05
Thu 2012-12-06
Fri 2012-12-07
Sat 2012-12-08
Sun 2012-12-09
Mon 2012-12-10
Tue 2012-12-11
Wed 2012-12-12
Thu 2012-12-13
Fri 2012-12-14
Sat 2012-12-15
Sun 2012-12-16


Test script:
---------------
// function strtotime called on Sun 2012-12-09
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-09"))); // Mon 2012-12-10
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-09"))); // Sun 2012-12-16

// function strtotime called on Mon 2012-12-10
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-10"))); // Mon 2012-12-10
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-10"))); // Sun 2012-12-16


Expected result:
----------------
If Sunday is start of the week then "sunday this week" be less than "monday this
week":

// function strtotime called on Sun 2012-12-09
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-09"))); // Mon 2012-12-10
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-09"))); // Sun 2012-12-09

// function strtotime called on Mon 2012-12-10
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-10"))); // Mon 2012-12-10
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-10"))); // Sun 2012-12-09

If Monday is start of the week then "monday this week" should return different values on
sunday and monday:

// function strtotime called on Sun 2012-12-09
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-09"))); // Mon 2012-12-03
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-09"))); // Sun 2012-12-09

// function strtotime called on Mon 2012-12-10
echo date("D Y-m-d", strtotime("monday this week",
strtotime("2012-12-10"))); // Mon 2012-12-10
echo date("D Y-m-d", strtotime("sunday this week",
strtotime("2012-12-10"))); // Sun 2012-12-16

Actual result:
--------------
See test script, actual result is present alongside each line.


------------------------------------------------------------------------



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