Edit report at https://bugs.php.net/bug.php?id=61185&edit=1
ID: 61185
Comment by: eitan at mosenkis dot net
Reported by: php-bugs at shimi dot net
Summary: jdtojewish return values incompatible with
cal_days_in_month on non-leap years
Status: Open
Type: Bug
Package: Calendar related
Operating System: Linux
PHP Version: 5.4.0RC8
Block user comment: N
Private report: N
New Comment:
Duplicate of 54254
Previous Comments:
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[2012-02-26 09:10:15] php-bugs at shimi dot net
Description:
------------
Preamble:
Please bear with me for the long explanation, it is my reasoning for the
request I'm going to give in the end.
I'm pretty sure the code I'm testing now worked a few years ago; I have
specific code that actually checks if the Jewish year is leap, and if so, add 1
month to all calculations after the 6th month if the year is leap.
Now my code is broken. Regardless if it really worked in the past or not, I see
an incompatibility between two calendar functions, which I think should be
aligned together.
My code calculates the dates of many Jewish events, according to the Jewish
calendar. For those who are not familiar with the Jewish calendar - not every
year has the same amount of months. If the (Jewish year % 19) is 0, 3, 6, 8,
11, 14 or 17, then the year is "leap" (I don't have a better word in English),
and an additional month is added between the 5th month (Shvat) and the 6th
month (Adar). The new month added is also called "Adar" (and denoted "Adar A",
while the original Adar becomes the second, and denoted "Adar B", so the
holiday that we have in Adar every year, remains in B).
Now, at the moment, we're in an Adar month (which is why the bug popped out),
but this is not a leap year (Jewish year now is 5772 % 19 = 15), so we have
only one Adar month.
Now, as memory serves me (and as written in my code), cal_days_in_month could
accept 1-12 as valid month on non-leap years, and 1-13 on leap years. My code
has tests for those things, and acted accordingly. Now, it appears, that
cal_days_in_month always accepts a 1-13 value, and simply expect the programmer
to jump over the 6th month, returning "0" if there was no Adar A added before
the regular Adar.
This is OK! Actually, it makes all my calculations of leap years - redundant.
The problem is - that even though cal_days_in_month understand that the
_current_ month is actually the 7th (as we "skipped" the 6th of 13 of a leap
year), jdtojewish, the function that gives you those dates in the first place,
says that we're in the 6th month...
I think that if cal_days_in_month thinks there is no 6th month this year,
jdtojewish should never return the number "6" for this year.
[p.s. example code will not show the mentioned problem in ~28 days when the
Hebrew month changes, but will probably return a wrong day count...]
Test script:
---------------
Code:
<?php
list($jewishmonth, $jewishday, $jewishyear) = explode('/',
jdtojewish(gregoriantojd(date('m'), date('d'), date('y'))));
echo "Jewish month is $jewishmonth. How many days do we have this month? " .
cal_days_in_month(CAL_JEWISH, $jewishmonth, $jewishyear) . "\n";
?>
Expected result:
----------------
Jewish month is 7. How many days do we have this month? 29
Actual result:
--------------
Jewish month is 6. How many days do we have this month? 0
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Edit this bug report at https://bugs.php.net/bug.php?id=61185&edit=1
