Re: At what year does (yy, mm, dd) become (19yy, mm, dd)?

On 2008-05-07 15:56, Dick Moores wrote:
> On Wed, May 7, 2008 at 4:36 AM, M.-A. Lemburg <mal@...> wrote:
>> On 2008-05-07 12:09, Dick Moores wrote:
>>> For mxDateTime.
>>>
>>> I know I saw this in the manual, but I can't locate it again.
>>    Note about the Y2K problems:
>>
>>       The parser can only handle years with at least 2 digits. 2
>>       digit year values get expanded by adding the century using
>>       DateTime.add_century(), while 3 digit year get converted
>>       literally. To have 2 digit years also be interpreted literally,
>>       add leading zeros, e.g. year 99 must be written as 099 or 0099.
>>
>> def add_century(year):
>>
>>    """ Sliding window approach to the Y2K problem: adds a suitable
>>        century to the given year and returns it as integer.
>>
>>        The window used depends on the current year (at import time).
>>        If adding the current century to the given year gives a year
>>        within the range current_year-70...current_year+30 [both
>>        inclusive], then the current century is added. Otherwise the
>>        century (current + 1 or - 1) producing the smallest difference is
>>        chosen.
> 
> Sorry, but I can't follow that. Please give some examples. From my own
> testing, I can see that for current year 2008, if 2-digit years are
> represented by yy, then if yy <= 38, the century is the 21st (20yy).
> Whereas if yy > 39, the century is the 20th (19yy). But I don't