Hi,

At Tue, 11 Aug 2009 00:47:44 +0900,
Angel Pizarro wrote in [ruby-core:24851]:
> Round trip errors for edge case dates:
> 
> Jan 01 2008 
> 
> Date.strptime(Date.parse("Jan 01, 2008").strftime("%Y%U") , "%Y%U") 
> ArgumentError: invalid date
> 
> Dec 31, 2008 
> 
> Date.strptime(Date.parse("Dec 31, 2008").strftime("%Y%W") , "%Y%W")
> ArgumentError: invalid date

%U and %W mean week numbers, so the results, "200800" and
"200852" don't have enough info to determine their date.
You need to include %w together.

$ ruby -rdate -e 'p Date.strptime(Date.parse("Jan 01, 2008").strftime("%Y%U%w") , "%Y%U%w")'
#<Date: 2008-01-01 (4908933/2,0,2299161)>

$ ruby -rdate -e 'p Date.strptime(Date.parse("Dec 31, 2008").strftime("%Y%W%w") , "%Y%W%w")'
#<Date: 2008-12-31 (4909663/2,0,2299161)>

-- 
Nobu Nakada