Description:
------------
The Date function have an ISO compilant Week parameter 'W'

This parameter should return leading zeros for week 1 to 9 (always returning 2 digits). 

Why

http://se.php.net/date :
> W   ISO-8601 week number of year, weeks starting on Monday 
> (added in PHP 4.1.0)

This week parameter do not return leading zeros when used like Date('W'), Date('o\WW') etc. for the weeks 1 to 9

According to ISO 8601 weeks should be represented with leading zeros (from section 4.8 Leading zeros
Each date and time component in a defined representation has a defined length, and leading zeros shall be used as
required.) like:

Date       - Week (extended format)
---------- - ----------
1997-12-29 - 1998-W01-1
1998-01-04 - 1998-W01-7
1998-01-01 - 1998-W01-4
1998-12-31 - 1998-W53-4
1992-01-01 - 1992-W01-3 
1992-02-29 - 1992-W09-6
1992-12-31 - 1992-W53-4
1975-01-01 - 1975-W01-3 
1975-12-28 - 1975-W52-7 
1975-12-29 - 1976-W01-1 


Sources
Here's a copy of the latest free online copy http://www.pvv.org/~nsaa/8601v2000.pdf, only minor changes in the text in the latest version from ISO - also see http://en.wikipedia.org/wiki/ISO_8601.





Reproduce code:
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ECHO date('W',strtotime('4 January 1999'));

Expected result:
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01

Actual result:
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1